Tug Pilot Manual

It is important to remember that as a Tug Pilot you have considerable responsibility to the London Gliding Club. Aero-towing is an expensive and noisy operation. Both factors have a bearing on the very existence of the gliding club and it is essential, therefore, that Aero-towing be carried out efficiently and thoughtfully, particularly with regard to our neighbours.

Aero-towing should be carried out in accordance with the following procedures and in conjunction with the London Gliding Club’s Operations manual and Club Rules. Within these constraints the glider pilot’s requirements should be accommodated as far as possible.

1.2 APPROVAL TO FLY TUG AIRCRAFT

Initial approval to fly tug aircraft will be issued by the Chief Tug Pilot (CTP), after discussion and approval from the CFI and Deputy Chief Tug Pilot (DCTP). See Pilot Details for current list of Tug Pilots.

Each Pilot will be checked annually and his approval reviewed. The flying check will be done by the Chief Tug Pilot, DCTP or a Check Pilot.

Specific authorisation and in some cases differences training will be required for the following;

1. Any flight away from Dunstable.

2. Retrieves from fields.

3. Retrieves from airfields. See section 1.22 and Approved Airfield list.

3. Dual aero-tows.

4. Aero-towing with the Super Cub. Current Pilots can be found under Pilot Information.

5. Aero-towing with G-LGCA. Current Pilots can be found under Pilot Information.

5. Aero-towing with any other aircraft that may be used from time to time by the London Gliding Club.

6. Aero-towing from the East run (See 1.8.5).

These authorisations will be issued by the CTP.

A flying check/refresher with the CTP or DCTP is necessary if no tug flying has been done for 3 months or more.

An approved tug pilot may not fly if his medical or licence has lapsed. The onus for keeping medicals current rests with the pilot. On renewal, the new expiry date should be passed to the CTP. This information is held under Pilot Details.

1.3 LICENCES and MEMBERSHIP

Each tug pilot must be a full flying member of the London Gliding Club. The current list can be found under Pilot Details.

Each tug pilot must hold a valid Pilot’s Licence. This must include the following;

1. A valid medical certificate.

2. A valid Certificate of Revalidation or a PPL issued within the last 12 months. The Certificate of Revalidation is valid for 24 months, the expiry date will be specified in the Licence.

The Certificate of Revalidation contained in the licence must be signed and be current for “SE Piston(land)” aircraft. Any JAA Type or Class Rating Examiner (TRE or CRE) may sign the certificate, once he is satisfied that 12 hours P1 have been completed on any SE piston aircraft during the preceding 12 months. AND;

He has completed at least 1 hour’s flying with a Class Rating Instructor (CRI) in the preceding 12 months. The flight is essentially a general handling and aero-tow refresher, it follows a format determined by the BGA. Revalidations are lodged with the CAA for general licence usage.

JAR reference and an example of a completed FCL150CJAR form in the licence. Note that for holders a TMG endorsement, this can be combined with the SEP revalidation. For those with SLMG, it can revalidated on the "National" page or by stamp in the logbook, but does require standalone recency compliance.

Completion of any Licence Skill Test in the preceding 12 months can be substituted for the 1 hour Flight Refresher at the discretion of the Class Rating Examiner.

See Pilot Details for current CAA/JAR Authorised Examiners.

1.4 ENGINE HANDLING

All LGC aircraft are fitted with 180HP Lycoming O-360 engines. Section 4 gives full details of this engine.

Glider towing is very hard on engines, due to alternate use of high and low power settings. Cylinder head cracking can happen when rapid changes (temperature “shocks”) or differential changes in temperature occur in an engine. With our operation this is on take-off when applying full power and most critically at the release point of the launch, when power reduction is aggravated by an increase in airspeed and consequent increase in ram air cooling. Standard operating procedures have been devised to minimise thermal shocks, and manage the engine’s temperature profile.

Specific engine handling procedures are listed under the relevant “Robin” and “Super Cub” operating notes in sections 2 and 3 of this manual.

1.5 NOISE ABATEMENT

Continual towing or descent over the same area causes considerable nuisance and irritation to our neighbours. Whilst we can do little to reduce the actual noise produced, we can spread the load by thoughtful and varied tow-out patterns. It is variation, therefore, that forms the basis for our noise abatement procedures. The following general points should be considered, along with specific procedures as laid down in section 1.8 Launch Points.

1. Avoid over-flying all houses just after take-off (See 1.8 Launch Points).

2. Fly around or downwind of Edlesborough, Eaton Bray and Totternhoe until at least 1500’ agl. Do not fly over Dunstable below 1500’ agl. Refer to Figure 1.

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Figure 1

3. Use the airspace immediately overhead the London Gliding Club (See 1.7 Local airspace).

4. Make full use of all airspace available to us within the Luton SRZ (See 1.7 Local Airspace).

5. It is not always necessary to drop upwind, a tow made for the most part downwind of the site and then terminating overhead or slightly upwind of the site, can sometimes be used.

6. Remember that when turning, the focal point of your turn (the lower wing will be pointing at it) will be subjected to a concentration of tug noise.

7. A soaring pilot may be happy to be towed directly away from the site, this should be done when the opportunity arises.

8. Evenings and Sundays are particularly sensitive periods.

Remember that the noise of a descending tug with a relatively high power setting can be equally annoying, apply the same techniques in descent as well. Also, try and make your descent route different from the tow out route. Do not descend below 500 feet until entering base leg.

1.6 OPERATIONAL REQUIREMENTS

1.6.1 It is the tug pilots responsibility after full consultation with the instructor in charge, to terminate aero-tow operations when darkness approaches. Do not launch a glider after sunset + 10 minutes. Resist all forms of persuasion to launch in these circumstances. In order to establish the precise time sunset tables are reproduced on the front cover of each Tech. log and in Sunset Table. Advise the instructor in charge of this time a little in advance.

1.6.2 It is the tug pilot’s responsibility to terminate aero-tow operations if visibility, wind strength or cloud base make operations hazardous. Some of these limits will depend on the type of tug in use.

1.6.3 Before every take-off, check that the winch launch is not taking place or about to take place (see also 1.9 Radio Procedures). If it is, delay launch until the cable is back on the ground. Do not take off across the winch cables.

1.6.4 If non-radio; do not take off unless a forward signaller is in position. In exceptional circumstances (e.g. organised evening flying), a forward signaller may be dispensed with if signalling is specifically arranged to be via the tug’s rear view mirror.

1.6.5 Before take-off note on the Tug Log Card the glider, name of pilot to be charged and the take-off time. Subsequently record the exact aero-tow release height (to the nearest 100’). These cards are essential for rendering launch charges to Club members and must be legible and accurate. For example a release at 2100 feet should be recorded as such and not as 2000 feet.

1.6.6 Cloud flying with a glider on tow shall not be undertaken without prior arrangement with the glider pilot and then strictly at the tug pilot’s discretion.

1.6.7 Ensure adequate clearance of the tow rope from the ground when approaching to land, this is particularly important on the East and South West runs. Do not overfly people, aircraft or vehicles prior to landing.

1.6.8 Do not land tug aircraft on hangar ridge or on the new ground to the South East of the trailer racks.

1.6.9 Passenger carrying is NOT allowed whilst Aero-towing. Exceptions to this rule must have specific authorisation from the CFI, CTP or DCTP.

1.6.10 ALL flights away from Dunstable require authorisation from the CFI, CTP or DCTP.

1.6.11 Anti-collision lights, where fitted, should be on whenever the engine is running.

1.7 LOCAL AIRSPACE

General

The airspace around Dunstable is complex and subject to change. A thorough working knowledge of the local geography and position of airspace boundaries is essential for all tug pilots. Tug pilots can be expected to be checked regularly on their knowledge of this. The Local Airspace section of the website shows the local airspace and it’s restrictions. It also shows the airspace in which aero-towing can take place when Luton are operating their runway 08. This information is subject to change from time to time and will be shown on the latest CAA 1:500,000 Southern England chart and/or the Letter of Agreement we have with LATCC.

1.7.1 All tug pilots must have an Airspace Rating for operations in and around the London Gliding Club.

1.7.2 All tug pilots must be familiar with the aero-towing concessions available when Luton are using 08, and make appropriate use of them.

1.7.3 All tug pilots must be familiar with the boundary between the 3500' based CTA and the 4500' based CTA, in order to take gliders requiring 4000' tows legally and efficiently to the an optimum position below the 4500' CTA. Diagrams and key features to achieve this are included in the Local Airspace part of this website.

1.7.4 Aero-tows should also make use of 26 airspace when Luton are using 26, but locally the Status is 08. Landing direction at Luton is constantly promulgated on Luton ATIS 120.57. This should monitored and confirmed before entering the 26 area.

1.7.5 Occasionally glider pilots will request an aero-tow above 4000'. This can be done towards the North West under the Daventry CTA. The tug pilot must know these boundaries before agreeing to the tow.

1.8 LAUNCH POINTS

1.8.1 General

Each take-off and landing direction at Dunstable presents the Tug pilot with particular problems and specific procedures to follow. Listed below are notes and diagrams relating to each of the take-off and landing directions.

There is considerable risk to people and gliders when an engine is running. Therefore, Tugs should always be parked and taxiied well away from the Launch point area. As a rule, a Tug should not approach closer than 10 metres to a glider awaiting launch, normally a greater and safer distance can be achieved.

1.8.2 South West Run (Figure 2 and 3)

Launch position; Gliders must be parked as shown on Figure 2. There is enough room for two K21’s side by side, providing the Control tower is correctly positioned.

Take-off; The take-off path must be kept within the area shown on Figure 2, That is between the 12 metre wide sterile area towards the gulley and the central cable pull-back line. If necessary the glider must repositioned to facilitate a safe take-off within the boundaries described. The surface on the Clubhouse side of the cables is too rough and must not be used for Take-offs.

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Figure 2

Routing; There are two early route options, as shown on Figure 3, either route between the pig farm and the Tring road (A) or between the pig farm and the hill (B). The second option (B) requires adequate climb performance in order to comfortably clear the power lines. Don’t overfly the winch. Be aware that gliders or vehicles on the North East run landing area may not be visible from the launch point.

Landing; The approach should always be steep enough to avoid any possibility of the rope fouling the public footpaths on the airfield boundary. If the surface of the downslope of Hangar ridge is kept in view at all times during the approach, then an adequate margin will be achieved. Always land on the upslope beyond the dip. Note that the upslope is steeper towards the Tring Road. A few extra knots may be useful to counter the effects of the upslope.

Beware of curlover on short finals and in the dip in strong wind conditions.

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Figure 3; The South West run

Landing long or on the East run are alternatives for a crowded landing area.

If possible taxi back along the sterile area shown on Figure 2. If returning via Hangar ridge, try and anticipate power requirements for climbing the slope in order to avoid high static power settings and in any case avoid the very steep slope near the launch point.

Parking; Tugs should be parked in line with the edge of the gulley and well forward of the launch point area as shown in Figure 2.

Grid position; If a Grid is formed on this run it will normally be on the hill side of Hangar ridge. Tugs will position about 2/3 of the way up Hangar ridge and take-off downhill. Exercise care with power and brakes in these circumstances. Parking of tugs for this launch should be on the hill side of the upslope and at 90° to the slope or slightly uphill in the case of the Super Cub.

1.8.3 North East run (Figure 4)

Launch position; This should be set up to the left of the Control Tower and consist of up to two gliders abreast. Further gliders should be queued behind or to the left. If the gliders are placed too far from the Control Tower the take-off path will be compromised.

It is also important that the Control Tower is positioned correctly to permit full utilisation of the tug take-off area. This is approximately 50m from the end of the hedge towards the hill. If necessary reposition correctly before commencing operations.

Take-off; Before commencing a take-off a midfield batman (M) must be in position and confirm “clear over the brow”. The normal take-off direction will be to the right of the bushes whilst keeping to the Tring road side of the trailer racks. Ensure you have enough clearance from the bushes to accommodate an out of position glider or large wingspan glider, this is particularly important with a crosswind from the right. This route will take the aero-tow over the Club entrance. Ensure that the ground run is contained within the recently prepared take-off area.

Routing; The initial route provides two options; Straight out to the left of “The Avenue” (B) or a left turn downwind (A - between Totternhoe and the Tring Road) to return overhead later. The first and simplest option (B), is particularly noise sensitive and should be used sparingly. Preference for this route should be given to training gliders where possible. Try and keep the ratio route A to route B to 2:1 or better.

Landing; Landings should be made to the right of the launch point. This will mean crossing the winch cables when taxiing back. Ensure that you cross well ahead of the winch launch point and cross at 90°, continue on this heading until the tow rope has definitely cleared the cables without snagging before turning towards the launch point. Exercise extreme care. Use the radio to advise if required. Alternative for landing is to the left of the aero-tow launch point. This option requires a high approach to keep the tow rope from snagging the fence on the airfield boundary and an inevitable long landing.

Beware of downdrafts on short finals in strong wind conditions.

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Figure 4; The North East run

Parking; Tugs should be parked well away from gliders and into the Western corner of the airfield.

Grid Position; If a large grid is required it will have to cover the area of the normal winch and aero-tow launch points combined. A smaller grid should be two gliders wide as for normal operations.

1.8.4 West run (Figure 5 and 6)

Launch position; Normally gliders will be two abreast to the left of the Control vehicle.

Take-off; This take-off run is particularly noise sensitive and the direct overflying of the houses on the Tring road must be avoided at all times. This then gives 3 alternative take-off paths as shown on Figure 6. The most Northerly (A) goes very close to the winch and special care must be made to co-ordinate with the winch launch point. The middle option (B) keeps just to SW edge of the hedge line. The Southerly option (C) has a bit more space but goes very close to a riding school, try and avoid their training arena as well as the buildings (marked RS on Figure 6).

There is a tendency for gliders to align themselves parallel to the winch cables, which implies taking off on route A. It is important that we cycle through the various take-off routes and this may mean realigning the glider. Some gliders will easily re-align themselves on the take-off run if the tug is properly positioned (see Figure 5). However, heavy tailed gliders cannot easily do this and must be realigned before take-off. These include ASH25, ASW22, DG500, Nimbus and similar types.

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Figure 5

Routing; On route A, a 30° turn to the right must be made soon after take-off, in order to avoid over-flying any of the Wellhead houses. This often means overflying the winch. Then the preferred turn direction is to the South (A1). If a right turn is made, it will take the aero-tow close to the noise sensitive Western edge of Dunstable. This option should therefore be rationed left turnout (A1) to right turnout (A2) in the ratio 2:1 or better.

Routes B and C require flying straight ahead on the appropriate line until passing the Wellhead houses when a left turn should be made.

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Figure 6; The West run

Landing; Landings as for take-off are not possible, although some gliders can be expected to do this. If a left hand circuit is in progress, then the approach and landing should be into the North East glider landing area and flown as if the North East run were in operation (marked LH on Figure 6). The final landing direction may be angled into wind if necessary. In this case the Tug must be kept on the airfield side of the hedge line (marked H on Figure 6).

Care should be taken to avoid any low steeply banked turns which could be affected by wind gradient effects.

If landing cross-wind in front of the launch point, often the best option, maintain a good distance forward of the launch point and ensure a clear path is available in front of you, to facilitate an overrun or a go-around.

If a right hand circuit is in operation, then land as for the South West run (shown RH on diagram 6) and take care when crossing the winch cables.

Grid Position; There are few problems with locating a Grid on this run, however, the take-off routes should be maintained.

1.8 .5 East run (Figure 7)

Aero-tow operations from the East run can be extremely hazardous due to curl over and the requirement to turn immediately after take-off. Therefore all other take-off options must take preference. Discussion with the duty Instructor may be required. If a decision to launch Easterly is made, then only the Super Cub should be used because of its superior field performance. However it’s reduced crosswind capability may be restrictive, only 10kts crosswind component is permitted. If a crosswind is present do a "Flaps up" take-off, this technique is desrcibed under Super Cub operating procedures 3.7. Launching heavy gliders will compromise safety margins, therefore, the following gliders will not be permitted launches from the East run; ASH-25, ASW-22, DG500, DG505, Glasflugel 604, Janus, Nimbus 3, Nimbus 4 or similar types and ALL water-ballasted gliders

It should be noted that Tug Pilots must be specifically cleared to operate from the East run.

Launch position; The launch point for the winch should be established on the edge of the new ground with two lines. A third line, immediately to the right, should be used for the aero-tows.

Take-off; Angle the take-off run as much as possible to the South West. It is possible that some of the take-off path will be obscured and a mid-field bat may be required. When airborne and accelerating commence a shallow banked turn away from the hill. In most cases this will permit a flight path between the pig farm and the Tring road. The air is likely to be very turbulent, especially in the area marked with x’s (Figure 7), this may give the glider control problems and in turn compromise your position. Be extra vigilant and don’t hesitate to use the glider release.

Routing; Once past the Tring road a left turn back towards the Club (A) or the hill (B) may be made. Route B is the preferred option and minimises noise nuisance, but do keep within our Airspace, the boundary of which is detailed under Local Airspace. The landing direction at Luton will almost probably be 08. Remember to keep above 1500’ when over Dunstable.

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Figure 7; The East run

Landing; The normal landing area is to the right of the bushes and towards the hill. A steepish approach will be necessary to ensure clearance of the tow rope over the power lines (marked PP) situated along the Tring road. Landings in front of the launch point may only be made when there is no winch operation.

Beware of downdrafts on short finals in strong wind conditions.

Grid Position; It is not feasible to Grid on this run.

1.9 AIRSPEED INDICATORS

Each tug is fitted with an Airspeed Indicator calibrated in knots. The instrument carries the conventional coloured arcs. That is;-

Green Arc - Clean/Max manoeuvre range

White Arc - Flap operating range

Yellow Arc - Caution range

Red line - VNE.

In addition two further markers have been added to improve glider towing operations. These are a glider tow reference arc and a single descent speed marker. See figure 8 below.

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Figure 8

Approach speed

Approach speeds for each type will vary. As a guide, in calm conditions, the approach speed should not be less than the minimum tow speed marker. Additions for wind strength and gradient should be applied to this.

1.10 RADIO PROCEDURES

A 720 channel radio, along with intercom and headsets is fitted to all tugs. The radio should be used for all towing operations. The headset doubles as an ear defender and provides for clear radio usage. The earphones are fitted with a separate volume control. PLEASE take care of the headset and stow carefully when not in use.

The radio will be used primarily for receiving Pilot’s name, Glider, any special instructions etc. and also the “Up slack” and “All out” signals. These radio messages have to be backed up by visual signals, which the wing tip holder will continue to do, however the forward signaller can be dispensed with under this system.

The frequency to be used will be 119.9.

The following stations should have radios;

Station Call-signs

Tugs “XRAY INDIA”

”CHARLIE ALPHA"

“UNIFORM ALPHA”

“YANKEE MIKE”

Winch “WINCH”

Midfield bat “MIDFIELD”

Launch point “DUNSTABLE RADIO”

LGC Office “OFFICE”

These will be prefixed with “DUNSTABLE” if any conflict occurs. Likewise with several tugs operating, the launch signals should be prefixed by the tug in question, e.g. “XRAY INDIA UP SLACK”. The tug pilot should reply with his call-sign only, “XRAY INDIA” in this example, unless the request is not possible. The “ALL OUT” will be acknowledged by commencing take-off.

During midweek operations, only a few of these stations will be operating. However, a general transmission such as “UNIFORM ALPHA LAUNCHING” should be made at the start of the take-off.

If you are doing something unusual, e.g. Landing in a different area of the airfield, taxiing across the winch cables or returning to refuel, then announce your intentions on the radio.

1.11 AERO-TOW SIGNALS

1.11.1 To order the glider to release

Rock the wings of the tug. The action should be positive, ideally 45^° bank to the left then 45^° to the right. The glider should release immediately, this will then permit the right bank to become the parting manoeuvre.

This signal is often used during competition launches, where a “wave off” at 2000’ is the normal release method.

1.11.2 The signal from the glider pilot to say he is unable to release

The glider pilot should fly his glider out to the left of the tug as far as practical and rock the glider’s wings. In this case, operate the glider release and leave the tow rope with the glider. It may be necessary to tow to a suitable position before doing this.

NOTE; Some Gliding Clubs have a signal to inform the glider pilot that his air-brakes are open. We have no such signal and none should be attempted. See 1.12.2 Rejected Take-off and 1.12.3 Glider air-brakes open.

1.12 EMERGENCIES

1.12.1 General

Every pilot must be continually aware of possible emergency situations occurring during towing operations.

The Glider Release handle must be immediately accessible and used if the glider prevents your control of the tug. Many accidents to tugs have occurred in the past due to the tug pilot’s failure to release his glider. Whilst we must have concern for the glider pilot, the safety of yourself and the tug is paramount.

1.12.2 Rejected take-off

Once full power has been set, check the RPM, if it is not up to the normal value for the aircraft, reject the take-off. At around 20 to 30 knots check in the rear view mirror; if the gliders’ air-brakes are open, release the glider immediately and reject or take-off as appropriate.

If a take-off is rejected, then release the glider and roll on in a straight line as far as possible. This will allow the glider space to manoeuvre behind the tug.

1.12.3 Glider air-brakes open

Attempting a take-off where the glider has its air-brakes deployed is extremely dangerous, in most cases the glider pilot will not realise the problem. An early release when airborne will probably result in a glider accident. In some cases the combination will not be able to climb and there is no alternative then, but to release the glider. If a climb is possible then the combination should be positioned onto base leg or finals such that when released the glider will make the landing area with its air-brakes fully deployed. Do not attempt to signal to the glider. Radio communication may be possible.

1.12.4 Engine failure

Tug engines are as likely to fail as other light aircraft engines, your knowledge and competency of emergency landings and the associated vital checks is essential. On your first flight each day, check out the forced landing options.

Remember that a stopped propeller will steepen the “idle power” glide angle. Also the type of propeller fitted will affect the tug’s glide angle, a four-bladed propeller, in particular, will further steepen the glide angle dramatically.

1.12.5 Tug upset

From time to time over the years, tug upsets have occurred at low level from which the tug has been unable to recover, usually with fatal results. A glider pilots’ aero-tow training emphasises that correct position behind the tug is essential and that he must release if he is losing control. However, tug pilots must be vigilant during the early stages of the launch for any tendency of the tug to be pitched nosed down. Below 600 feet, monitor the tugs’ attitude and if a gentle back pressure is insufficient to prevent any nose down pitch - release immediately. Above 600 feet, the glider pilot may be given the opportunity of correcting the situation. Be aware that tug upsets can happen rapidly with little warning.

There are a number of factors which increase the possibility of a tug upset;

1. A glider that is to be towed from a belly hook.

2. Gliders with high set wings relative to the towing hook.

3. Gliders with a low wing loading, usually older or vintage types.

4. The presence of turbulent conditions, especially if associated with a strong wind gradient or if the wind is off the hill. The East run at Dunstable is particularly critical in this respect.

5. Glider pilots with low hours and/or aero-tow experience.

6. Lightweight pilots

7. The use of short tow ropes will exacerbate the problem.

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Figure 9

A typical sequence is shown in figure 9, with a simplified rope load/ angle plot in diagram 10. In reality the situation is worse than shown because the glider zoom climbs behind the tug, its total energy increases (simultaneous increase in height and speed). This energy can only come from the momentum of the tug and therefore its speed will rapidly decay. This means that just when a high down load is required to be generated by the tailplane/elevator to retain control and break the weak link on the rope, its capability to do so is vastly reduced by the decay in airspeed. This may result in the tailplane, and possibly the wing, stalling. Typically, up to 600 feet may be required to recover from an upset.

Also avoid a hasty transition from level acceleration to climb, as this will result in the glider becoming low relative to the tug. This can tempt the glider pilot to make a rapid recovery, with obvious potential for overcorrection.

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Figure 10

In addition, there are other destabilising influences for both tug and glider pilot, such as re-trimming, flap and undercarriage retraction, instrument scan, etc. For the tug pilot, retracting flaps should be left to a safe height, at least 300 feet.

Since upsets are, fortunately, rare events and tug pilots may not have experienced any before, the overriding advice is; Any unusual behaviour of tug or glider in the early stages of the launch is cause for immediate release of the tow rope. The analysis can be done afterwards.

1.13 ACCIDENTS AND INCIDENTS

After an accident or incident involving a tug, the tug pilot concerned must ground himself and notify the CFI and CTP as soon as possible. The accident or incident will be reviewed and tugging re-authorisation determined accordingly.

1.14 CHECKLISTS

There are no standard checklists issued. Every pilot must therefore use checklists which enable him to operate the aircraft safely. With reference to the section on Emergencies above, each pilot should have clear in his mind actions in the event of an emergency. Guidance from the CTP or DCTP is available if required.

1.15 WHICH TUG TO USE?

The Aircraft Status board in the tug hangar will give the priority order for using the tugs and should be adhered to unless weather conditions preclude the use of a high priority tug. It will also show if a particular tug is unserviceable or out of check. This information is updated by the manager or the Aircraft Engineer. Further information on individual tugs will be found in their respective Tech. Logs.

1.16 REFUELLING

It is the tug pilot’s responsibility to refuel his aircraft if fuel tanks are indicating less than a quarter full and at the end of the day’s flying.

1.16.1 Exercise extreme care when taxiing towards fuel pumps, and make sure the overhead refuelling pipes are stowed and the general area is clear. The tug should be taxiied straight in and stopped with the propeller disc just short of the white line.

1.16.2 Always connect the earthing strap to the exhaust pipe before attempting to refuel. Ensure all aircraft electrics are off.

1.16.3 Fill all tanks of the tug to FULL. The only exceptions to this may be prior to launching a competition grid, before setting out on an aero-tow retrieve or before maintenance. NB; The auxiliary tank on G-BVYM is normally left empty.

1.16.4 After refuelling, stow the overhead refuelling pipe, stow the earthing wire and move the tug away from the pumps for starting or parking

1.16.5 Record the uplift and meter readings in the Fuel Record book.

1.17 TUG RECORDS

1.17.1 Technical Log

The Tech. log is an important document as it provides a pilot with a current status report on the tug. It also records tug hours and forms a record of defects. The information from the Tech. log is used by the Aircraft Engineer to schedule maintenance checks and keep the required tug records.

The first page of the Tech. log itemises all outstanding defects and states when rectification will take place. Any flying restrictions will be written on this page. It is for the pilots information, either when taking over a tug or before completing the D.I. All items on this page will be entered by the Aircraft Engineer or CTP only.

A Tech. log page should be completed for each day’s flying. This page is completed in basically two stages. After the D.I., the pilot will enter any new defects, the tacho time, date and sign for the D.I. At the end of the day the last pilot will add any further defects, enter the tacho time, complete the hours column, add the number of tows done and sign the Tech. log. If during the day defects occur then they should be entered into the Tech. log at the time.

The Aircraft Engineer will vet all entries regularly. The Aircraft Engineer will arrange rectification or defer rectification to a specific check and annotate the Tech. log accordingly. The daily pages, once vetted will be removed.

Any queries regarding Tech. log entries should be made to the Aircraft Engineer or CTP.

1.17.2 Tug Log Cards

Records all information necessary for the treasurer to correctly charge Club members for aero-tows.

At the end of the day these cards should be deposited in the Club office or with the resident tug pilot.

1.17.3 Fuel Record

This is kept in the shed and should be completed for all uplifts of fuel.

1.17.4 Pilot’s Records

Details of pilot’s licence numbers, renewal dates, medicals, hours etc. will be held by the CTP and shown in Appendix 1, a current version of Appendix 1 will be on display in the Club office. For PPL holders, new renewal dates should be advised to the CTP. Please annotate the office copy with any other changes.

Please note that renewals are strictly the responsibility of the individual pilot.

1.18 TUG EQUIPMENT

The standard issue of removable equipment to each tug is;

2 tow ropes; 1 rope in use + 1 spare on board.

1 Peltor headset.

1 Clipboard, for tug log cards and pen.

1 Hand fire extinguisher.

The Tech Log and a copy of the Tug Pilot Manual.

Each tow rope is fitted with two weak links. A serviceable weak link will contain two staples, coloured either red or yellow. If a staple is broken or missing, it must be replaced before use. The yellow staples are rated at 1100lbs breaking strain, they are identified on the tow rope by a dayglo flag and one square wear protector, this end always attaches to the tug. The red staples are rated at 900lbs breaking strain and are protected by three square wear protectors, this is always the glider end.

Spare ropes, short field retrieve ropes and dual aero-tow ropes are stored in the tug hangar. Specialist ropes may not necessarily conform to the above weak link system.

Try and keep tow ropes clear of the “metalled” perimeter track. Cars and tractors running over the rope cause premature wear.

Do not leave tow ropes lying on the field overnight. One rope may be “snaked” on the hangar floor if its’ use next morning is anticipated.

Aircraft cleaning equipment is available in the tug hangar.

1.19 TUG HIRE

Tug aircraft may on occasions be available to hire. However, approval will always be required from the CFI or CTP. The pilot will be charged according to the charges shown in the LGC price list.

1.20 BOOKING IN/OUT

It is a legal requirement that all powered aircraft movements not starting and finishing their flights at Dunstable (i.e. most flights other than normal aero-tows) should be recorded. A movement book is located outside the main office, it has two sections, the first for visitors taking details of departure point and destination and a second section for LGC tugs recording either a destination or a departure point.

All aero-tow retrieves, positioning flights or hire flights should be entered along with the pilot’s signature.

1.21 GRID DAYS

The grid system may operate on a week-end or Bank Holiday cross country day when weather conditions are expected to suit cross country flying.

Please note the following requirements placed on ALL tug pilots when a “Grid” day is declared;

A “Grid” day will declared by 8:30 on a week-end day. If it is, then all tugs will be made available for the later grid launch.

If, when you arrive a serviceable tug is still hangared, then you should pull it out, DI it, taxi it to the relevant launch point and carry out the power check. This should be done regardless of who subsequently flies it.

Having done this task, if necessary, you may then turn your full attention to your gliding.

At Grid launch time, if there are not enough non-cross country tug pilots to fly the tugs, it may be necessary to help launch the first part of the grid. Towards the end of the grid it will be expected that you park the tug and you can then expect a priority launch at the end of the grid.

Tug pilots not flying cross country will be expected to return any “discarded” tugs to the hangar.

1.22 AERO-TOW RETRIEVES

A number of aero-tow retrieves are carried out each year. Generally, requests for “Airfield” retrieves will be accommodated if at all possible. “Field” or non-airfield retrieves will generally be discouraged because of the high level of associated risk. However it is accepted that some “Field” retrieves will be necessary, for example, to retrieve a K21 and bring it expeditiously back on line at LGC.

1.22.1 AIRFIELD and FIELD Categories

Retrieves will be one of two types, namely AIRFIELD or FIELD. Appendix 2 of this manual lists all airfields that may be considered for AIRFIELD retrieves. If the airfield is not listed or is a farmer’s field, playing field or private strip, then it is to be considered a FIELD.

1.22.2 Pilot Requirements

To carry out an AIRFIELD retrieve, a pilot must be AIRFIELD or FIELD rated (See Appendix 1 - Pilot Info).

To carry out a FIELD retrieve, a pilot must be FIELD rated.

AIRFIELD rating; To obtain an AIRFIELD rating a pilot must acquire a certain amount of aero-towing experience after completing basic training. This will normally be 150 tows or 25 hours. Additionally a briefing will be given by the CTP before being listed.

FIELD rating; FIELD ratings are deliberately limited to a few pilots. It requires a high degree of competency on Super Cub aircraft, a short course on theory, and some flying practice usually with the CTP. Once qualified it is important that a number of field retrieves are carried out in order to maintain competency. This is the main reason for limiting numbers.

1.22.3 Procedures

Before embarking on a retrieve it is important that the following points are addressed;

1. Permission must be obtained from the farmer or land owner to carry out an aero-tow retrieve from their land.

2. Permission must be obtained from the CFI, CTP or their deputies.

3. Tugs should normally be refuelled before departure.

4. The Tug Pilot must Book out. The Booking In/Out book is located just outside the main office.

5. A spare rope must be carried.

6. A suitable map must be carried.

7. Consider which aircraft to use. Factors may include cruise speed, onboard equipment, runway surface, base requirements. The authorisng person may have more information on this aspect.

8. Check Appendix 2 for any special procedures. The latest and most up to date Appendix 2 is contained on the Tug Pilot website.

9. If radio procedures are required, and most airfields do, then the Pilot must also hold an R/T rating.

10. Be aware of the logging procedure (see 1.22.4 below) and note Tacho time before departure.

1.22.3 Techniques

Before take-off ensure that you do the following;

Work out your contingency plan to cover actions in the event of an aborted take-off or in the event of rope break (release) soon after take-off. Brief the Glider Pilot accordingly.

Decide on a tow speed to suit glider and pilot. Decide how the signalling is to be arranged and any other relevant details.

Try and ensure you have radio communication between Tug and Glider.

After take-off, do a normal climb out until reaching 500’ agl, then accelerate to your agreed tow speed. Once a safe height has been reached or a chosen altitude, reduce power to achieve a slight climb or level flight.

Try to avoid the need to descend on tow, as it can be quite destabilising. If a descent is needed for cloud or airspace, then reduce power slightly to achieve a smooth 100-200 fpm descent, anything more will require the glider to use his airbrakes.

Surging is when the tow rope slackens and tautens continually. It can be caused by turbulence, lack of concentration on the part the Glider Pilot or by descending too quickly or inadvertantly. Surging can occur during level flight, but is most likely to occur during descending flight. The best solution is to apply power and accelerate or climb slightly until the surging ceases, then slowly return to the desired stable state.

Remember that until the glider releases, you are in charge of both aircraft and responsible for navigation and any RT calls.

1.22.4 Logging Procedure

The reverse of the Tug Log card contains a self explanatory form for recording aero-tow retrieves and other non-towing flights.

Note that for short retrieves, certain minimum charges will apply. A charge equivalent to a 3000’ aero-tow will be applied for a retrieve from Halton or Holmbeck Farm and a 2000’ charge for a retrieve from Eaton Bray or similarly close field retrieve. The times should still be recorded as above and the Office staff will apply these minimum charges.

Occasionally a visiting pilot will want an aero-tow retrieve from Dunstable. All the points in 1.22.2 must covered, in addition the Tug Pilot must take responsibility for ensuring a correct charge is made. The Manager should be approached in the first instance, in his absence, note as much relevant information on the Tug Log card so that a subsequent charge can be made.

1.22.5 Eaton Bray

Eaton Bray is a local small strip often used by LGC gliders. Pilots must be specifically cleared to tow from there.

In recent years the strip has become very restrictive, with the width being reduced to little more than 20 metres and with numerous obstacles at the South East end. Currently take-offs should only be made to the North West and with experienced Glider Pilots. Tug Pilot’s who have not aero-towed from there recently should seek advice on the current situation before attempting a retrieve.

1.22.6 Holmbeck Farm

A useful glider outlanding strip, situated between Wing and Leighton Buzzard. Pilots must be specifically cleared to tow from there.

This is a private microlight strip and quite restrictive, however, with appropriate conditions it can be used for aerotow retrieves. Tug Pilot’s who have not aero-towed from there recently should seek advice on the current situation before attempting a retrieve.

1.22.7 Feedback

Please feedback any useful information gathered whilst carrying out a retrieve in order that Appendix 2 can be kept up to date and valid.

2. ROBIN DR400 and DR300 OPERATING NOTES

2.1 INTRODUCTION

The following notes and procedures have been developed from the DR300 and DR400 Flight Manuals, knowledge of the engine’s cooling characteristics and many years of Aero-towing experience. Please adhere to the procedures listed. The Flight Manual may be consulted for supplementary information, a copy of which is kept on the aircraft. There are some differences between the types of Robin, notes specific to the DR300 are italicised, notes specific to G-LGCA are in bold.

2.2 GENERAL

2.2.1 In order to avoid damaging the flaps, the flaps should always be down when parked or hangared to facilitate entering or leaving the aircraft. Also when anyone approaches the aircraft lower the flaps to permit access.

2.2.2 The electric fuel pump should be ON whenever the engine is running.

2.2.3 On the ground the best engine RPM for cooling and avoiding plug fouling is 1000-1200 rpm.

2.2.4 All Robin aircraft are currently fitted with a wooden propeller, therefore there is no RPM restricted band.

2.2.5 Ensure all articles in the aircraft are strapped or tied down. The wide expanse of perspex is particularly vulnerable to loose objects.

2.2.6 A cylinder head temperature gauge is fitted. It can be switched between cylinders. For normal use it should be selected to cylinder No. 4.

2.2.7 An electric turn indicator is fitted. It is installed for emergency use only and is normally off. If required, it can be started by resetting the circuit breaker. It will provide useful information within 20 seconds. CA has a turn rate indicator and it should NOT be switched off.

The DR300 also has an air driven artificial horizon which cannot be turned off.

2.2.8 The DR400 has only two seats fitted and is only insured for one pilot and one passenger.

2.2.9 DR300 Fuel Tank usage; For most operations the auxiliary fuel tank will remain empty. If it is filled then the aircraft should be operated down to about half main tank. The auxiliary fuel knob should be pulled out, which will effectively refuel the main tank from the auxiliary tank. Once the auxiliary tank is empty the knob should be returned to the OFF or in position. Note; the system is NOT designed for the engine to run from the auxiliary tank.

2.2.10 CA has an hours meter which should be used for recording hours instead of the tachometer.

2.2.11 DR300 Canopy; Two gull wing doors with an awkward latching lever. Care is needed to ensure the locking pins are located correctly. There is a bottom pin beside the door latch and another at the top in front of the locking lever.

2.2.12 A Garmin 100 is fitted to supplement the VOR for cross country flying. It is important to remember to switch off the unit separately, by pressing and holding the OFF switch until the display blanks, before engine shutdown. Failure to do this will cause the internal nicad battery to flatten.

2.3 DAILY INSPECTION

Pilots must complete a daily inspection in accordance with the LAMS (Light Aircraft Maintenance Schedule - See Appendix 5) requirements and this must be recorded in the Tech. Log before flying commences.

In addition, special attention should be given to the following items;

1. Nose wheel leg - inspect for cracking particularly at the attachment brackets. This is important in view of the rough nature of the airfield.

2. Condition of the main landing gear - remaining oleo travel must be 2.75 inches or more. The top of the wheel fairing must be below the check hole in the fixed fairing when the aircraft is empty.

3. Cylinder heads - Look specifically for any cracks on each cylinder head. The most likely area is between the exhaust port and the spark plug hole on the lower side of the cylinder, but there are instances of cracks developing from small areas of corrosion between the base of the cooling fins. Cracks may be masked by general discolouration due to dirt, heat and/or paint flaking.

4. Air filter - not obstructed by debris particularly grass seed, or insects.

5. Condition and security of the propeller and spinner.

6. Tow rope release - check for correct operation and test under tension.

7. Condition of the tow rope and it’s weak links must also be checked (See 1.16 Tug Equipment).

2.4 START FROM COLD

Ensure the aircraft is parked on grass, clear of stones and debris. The aircraft should not be started in a position where the slipstream would affect other aircraft or gliders or where debris could be blown over aircraft, gliders or buildings.

To start

Parking brake ........................... SET

Flaps ............................................ UP

Mixture ................................ IN (Rich)

Prop .............................. Fwd (Fine)

Master switch ............................. ON

Alternator .................................. ON

Electric fuel pump ...................... ON

Prime cylinders with throttle

(2 to 4 pumps of throttle should be sufficient. If the engine is warm then a single pump will usually suffice).

Throttle .................... SET just off idle

Left magneto ............................... ON

Operate starter, when contact both magnetos ... ON

CA Starts on ignition key, Right Mag is temporarily isolated for start up.

After start

Check starter warning light ....... OUT

Throttle ............................. 1100 RPM

(Engine may need 1500 rpm initially to run smoothly)

Oil pressure .............. GREEN BAND

Anti-collision light ......................... ON

Radio ............................................. ON

Switch electric fuel pump OFF to check the serviceability of the engine driven pump, then switch ON again for normal operations.

Note: Carb heat bypasses the air filter and so should not be used on the ground, except to clear any ice that may be present.

2.5 ENGINE GROUND RUN

After the engine has reached a reasonable temperature, carry out a ground run up as follows;

Parking brake .................................. SET

Check clear behind

Throttle .................................. 1800 RPM

Carb heat .......................................... ON

Check for positive drop in RPM

Carb heat ........................................ OFF

Check each mag drop....Max 125 RPM

Check mag drop difference ... Max 35 RPM

Mags ................................................ Both

Prop ...... Pull out 3 - 4 cms, when RPM drops, immediately fully forward.

Wait until rpm fully recovers to original setting this may take 1 minute.

Throttle ............................... Slowly to idle

Check idle RPM ............... Min 800 RPM

After the run up, reset to ground idling at 1100 RPM. Providing that the engine is responding smoothly, there is no minimum oil temperature required before take-off.

2.6 TAXIING

With the nose wheel steering mechanism engaged, rudder pedal movement will then turn the nose wheel, further rudder pedal deflection will cause the wheel brake on that side to actuate. If the steering mechanism is not engaged only limited nose travel is available, in this case applying a little power with the stick forward should engage the mechanism. Very tight turns should be avoided as this is detrimental to the nose wheel steering mechanism.

The aircraft has a tendency to nod when taxiing over rutted ground, particularly Hangar Ridge. Taxi slowly and cross the ruts at 45 degrees. Also prevent the nose wheel from entering any significant dips or depressions. This will reduce the risk of tip contact.

Choose your route carefully and use only the smoothest areas of the airfield. Careful taxiing is also much less wearing on the nose leg.

2.7 TAKE-OFF

Use your normal Pre Take-Off Checks, and remember Fuel Pump should be ON and Flaps at “Take-Off”. CA: Make sure Prop control is fully forward. NB; If prop control was not returned to FWD in flight, the RPM may surge slightly on the subsequent take-off.

The take-off is a critical time for the engine. It is therefore important that opening the throttle at the start of the ground run should be gradual and take at least 3 seconds. On reaching full throttle check the RPM. This is very important and will give the first clue to engine problems. If RPM is low, check that carb heat is OFF before considering rejecting the take-off. See 1.11.2 for actions in the event of a rejected take-off.

On commencement of the take-off run the stick should be held well back. Lift off at or just below 50 knots. Hold the aircraft in the normal climbing attitude, the speed will increase rapidly to 60 knots which should be maintained to at least 300 feet. Retract flaps and climb at 65 knots (Normal).

CA: Once safely airborne and about the airfield boundary, slowly “unwind” the Prop control to a value between 2550 and 2600 rpm.

2.8 CLIMB SPEEDS

Normal Climb 65 kts Clean (CA: Normal Climb at 70 kts unless glider needs 65 kts)

Slow Climb 60 kts T/O Flap (Absolute minimum)

Fast Climb 70-75 kts Clean (Water ballasted gliders)

Note that higher speeds may be used for cruise climb or cruise when undertaking aero-tow retrieves. However, the speed must be agreed with the glider pilot beforehand, brief him if necessary.

2.9 DESCENT

At glider release; Stop the climb, acknowledge release by a short turn to the right, reduce power VERY SLOWLY to 2100 rpm [DR300 2000rpm], whilst accelerating to 100 knots [DR300 110 knots]. This is the most critical part of the engine operation and it is very important that the power reduction is achieved in NOT LESS THAN 30 SECONDS.

Initially fly 100 knots and 2100 rpm in descent, this will give a 1000 fpm rate of descent. If the opportunity to fly faster is available, then increase speed but do NOT retard the throttle any further. A speed of 105 knots will increase descent rate to 1500 fpm and the rpm increases to about 2200. A speed of 110 knots will give 1800 fpm and 2300 rpm respectively. Flying the descent in this manner will dramatically reduce flight times, but care should be taken to remain well clear of other traffic whilst descending at a high rates.

In the DR300 fly 110 knots and 2000 rpm in descent, this will give a 1000 fpm rate of descent. Unlike the DR400 with its’ four bladed propeller, the DR300 should not be flown faster to achieve a higher descent rate.

These parameters should be maintained to 500 feet, slowly retard the throttle to 1800 rpm [DR300 1500 rpm] and allow the aircraft to decelerate in level flight, in order to enter the base leg at 70 knots or less. Take-off flap may be selected at about 80 knots. Further reduce speed to 60 knots on finals (normal conditions) selecting landing flap as required to achieve a low power approach into the landing area.

The higher speed of the DR300 will require a longer descent distance and should be allowed for. Also the level deceleration phase is significantly longer and about ¾ mile is required compared with a ¼ mile with the DR400. Good circuit planning is required to accommodate these characteristics, whilst maintaining the necessary power settings.

Warning; It is possible to exceed the maximum rpm of 2700 in level flight with high power settings and even more readily in descent. Be alert to this and don’t exceed 2700 rpm.

CA Procedure;

At glider release; Stop the climb, acknowledge release by a short turn to the right, reduce power VERY SLOWLY to 23" MAP (12 o'clock position), then reduce to 2500 RPM, further reduce throttle to 12" MAP, whilst accelerating to 110 knots. This is the most critical part of the engine operation and it is very important that the power reduction is achieved in NOT LESS THAN 30 SECONDS.

Before landing AND after throttle has been reduced below 2200 RPM, push Prop control fully forward.

2.10 LANDINGS

Landings should be fully held off and the stick should be kept back on the decelerating ground run to keep as light a load as possible on the nose wheel. Brakes should be used cautiously.

2.11 WIND LIMITS

It is possible to operate the Robin in very strong winds, up to 40 kts. This strength of wind, however, is unlikely to be suitable for a safe aero-tow operation. The terrain around Dunstable creates extreme and unexpected turbulence. Consideration must also be given to type of glider and the glider pilot’s experience. It is important to remember that it is the tug pilot’s decision to aero-tow or not, if you are uncertain DON’T.

Maximum permissible crosswind is 22 knots.

2.12 SHUTDOWN

Idle the engine for a short period at 1100 RPM.

Switch ALL electrics OFF, including Fuel Pump, Anti-collision light and Radio. [If the GPS is switched on it MUST be switched off individually by pressing and holding the OFF button until the display blanks. Failure to do this will cause the internal nicad battery to flatten.]

Shut-down by closing the throttle and pulling the Mixture control to cut-off.

After the engine stops, switch Magnetos OFF and remove key. Pull Master switch OFF. The Mixture may be reset to avoid snagging whilst entering or leaving the aircraft.

2.13 REFUELLING

Refuel when fuel gauge falls below 40 Litres, and before hangaring at the end of the day. [The DR300 should have it’s main tank only refuelled. The auxiliary tank will normally be empty for aero-towing operations.]

Taxi up the ramp to the pumps, stopping with the propeller disc just short of the white line, this will allow the hose to reach the tank (See 1.16 Refuelling). Use the automatic cut-out on the fuel nozzle. Stop refuelling when it activates, this will avoid fuel spillage onto the wing walkway.

Record the uplift on the Fuel Record sheet (See 1.17.3)

2.14 HANGARING

Always put the Robin in the hangar tail first. Ensure that it comes out nose first. If it comes out tail first the tail skid can hit the tarmac and could fold back or break! When in the hangar, ensure the canopy is closed and a drip tray placed under the engine.

Before leaving the hangar, update the Aircraft Status board with details from the Tech. log.

2.15 TECHNICAL DATA

2.15.1 Engine data

G-BNXI G-BVYM

Engine Lycoming 180 HP O-360-A3A O-360-A4M

Max continuous RPM 2700 2700

Max cylinder head temp 260^°C 260^°C

Oil capacity 8 quarts 8 quarts

Min oil quantity 6 quarts 6 quarts

Oil pressure (idling) 25 psi 25 psi

Oil pressure (normal) 60-90 psi 60-90 psi

Max Oil temp 118°C 118°C

Fuel tank capacity (IG) 24.4 gallons Main 24.4 gals

Aux 11 gals

Unusable fuel (IG) 2.2 gallons 2.2 gals

Fuel tank capacity (Lts) 111 litres Main 111 litres

Aux 50 litres

Unusable fuel (Lts) 10 litres 10 litres

Fuel minimum pressure 0.5 psi 0.5 psi

2.15.2 Aircraft Data

Max take-off weight 1000 kgs 1000 kgs

Max landing weight 1000 kgs 1000 kgs

Empty weight 587 kgs 556 kgs

Main fuel load (24.4 gals) 79 kgs 79 kgs

Aux fuel load (11 gals) 36 kgs

Design load factors +4.4 g to -2.2 g clean config

Tyre pressures

Front 25 psi 26 psi

Mains 28 psi 29 psi

Limiting airspeeds

V_NE 157 knots 157 knots

V_NO 140 knots 145 knots

V_A(Manoeuvring speed) 116 knots 108 knots

V_FE 92 knots 92 knots

3. SUPER CUB OPERATING NOTES

3.1 INTRODUCTION

The following notes and procedures have been developed from the PA18 Super Cub Flight Manual, knowledge of the engine’s cooling characteristics and many years of Aero-towing experience. Please adhere to the procedures listed. The Flight Manual may be consulted for supplementary information, a copy of which is kept on the aircraft.

3.2 GENERAL

3.2.1 An LCD cylinder head temperature gauge is fitted to both Super Cubs. It can be switched between cylinders. For normal use it should be selected to cylinder No. 4.

3.2.2 An electric turn indicator is fitted. It is installed for emergency use only and is normally off. If required, it can be started by resetting the circuit breaker. It will provide useful information within 20 seconds.

3.2.3 The Super Cubs are currently fitted with metal propellers. If an A3A engine is also fitted, this imposes a restricted band on engine RPM. There is a risk of resonance in this area and therefore continuous power settings in the band should be avoided. The slow passage through the band after glider release is quite acceptable. The restricted band is between 2150 and 2350 RPM and the tachometer is marked by a red arc.

3.2.4 There are two fuel tanks and care must be taken to keep both reasonably balanced. The best time to change fuel tanks is towards the top of climb (see 3.8 CLIMB), changing tanks every 2 or 3 tows. Refuelling must take place when either tank is ¼ full.

3.3 DAILY INSPECTION

Pilots must complete a daily inspection in accordance with the LAMS (Light Aircraft Maintenance Schedule - See Appendix 5) requirements and this must be recorded in the Tech. log before flying commences.

In addition, special attention should be given to the following items;

1. Cylinder heads - Look specifically for any cracks on each cylinder head. The most likely area is between the exhaust port and the spark plug hole on the lower side of the cylinder, but there are instances of cracks developing from small areas of corrosion between the base of the cooling fins. Cracks may be masked by general discolouration due to dirt, heat and/or paint flaking.

2. Air filter - not obstructed by debris particularly grass seed, or insects.

3. Condition and security of the propeller and spinner.

4. Cowling fasteners - After checking the engine, make sure all cowl fasteners are securely engaged.

5. Undercarriage mounting - check for wear on the mounting/pivot bolts. This can be detected by rocking the wing up and down, from the tip, and observing if any movement is present at these pivots.

6. Undercarriage bungees - each leg is supported by two bungees and a safety strop. If a bungee has failed the aircraft will visibly lean to one side.

7. Lift struts - the wing lift strut lower attachment forks are vulnerable to cracks. By rocking the wings as in 5, any play will be felt or heard. NB; Do not lean on the lift struts when entering or leaving the aircraft or pull on them unnecessarily when manoeuvring the aircraft by hand.

8. Tailplane bracing wires - Pay particular attention to the bracing wire attachments at the end of each wire. Check for any cracks and security. Check that each wire is in tension.

9. Tow rope release - check for correct operation and test under tension.

10.Condition of the tow rope and it’s weak links must also be checked (See 1.16 Tug Equipment).

3.4 START FROM COLD

In cold weather, prime using six or seven pumps of the throttle before operating the starter.

In hot weather there is no need to prime, instead the throttle should be opened and closed fully twice to pump fuel into the induction pipe just before operating the starter.

The normal start procedure is to get the engine rotating properly before switching on the ignition. The left hand will operate the switches and then transfer to the throttle, pumping if necessary to achieve an engine start. The throttle should initially be ¼” open.

After start up, check the oil pressure, switch on the anti-collision light and any other required electrics and taxi. The cockpit check may be carried out whilst taxiing

3.5 ENGINE GROUND RUN

After the engine has reached a reasonable temperature, carry out a ground run up as follows;

Parking brake SET

Check clear behind

Throttle 1800 RPM

Carb heat ON

Check for a positive drop in RPM

Carb heat OFF

Check each mag drop Max 125 RPM

Check mag drop difference Max 35 RPM

Throttle Slowly to idle

Check idle RPM Min 800 RPM

After the run up, reset to ground idling at 1100 RPM. Providing that the engine is responding smoothly, there is no minimum oil temperature required before take-off.

3.6 TAXIING

Always taxi slowly and with the stick held back. If taxiing downwind the stick should be held forward, but allowed to “float” when power is applied. In these circumstances the flaps may bang about but this is to be expected.

3.7 TAKE-OFF

Use your normal Pre Take-Off Checks, and remember Flaps to be at “Take-Off”. Note the guidance for East Run operations below.

The take-off is a critical time for the engine. It is therefore important that opening the throttle at the start of the ground run should be gradual and take at least 3 seconds. On reaching full throttle, check the RPM, this is very important and will give the first clue to engine problems. If RPM is low, check that carb heat is OFF before considering rejecting the take-off. See 1.11.2 for actions in the event of a rejected take-off.

First stage flap should always be used when taking off from grass. During the take-off run the tail should be allowed to lift-off, but not too much since wing lift generated at this time will help to reduce hammering of the undercarriage. Lift-off should be allowed at 35 knots, followed by level acceleration to about 47 knots. Commence a gentle accelerating climb, to achieve 52-55 knots with first stage flap. This method is important since the Super Cub will happily climb away at 35 knots which could spell disaster for a glider on tow.

EAST RUN operations: It is most likely you will be faced with a crosswind from the left when operating on the East run. In this case adopt the following procedure.

1. Take off with Flaps UP.

2. Set the trim as you would when retracting flaps after take-off, typically 2 or 3 rotations nose up, but before take-off. This assumes the correct trim is left after landing.

3. Remember crosswind limit is only 10kts.

4. Commence a shallow banked turn soon after take-off, then increase to normal bank angles as altitude permits.

With flaps UP, speed increase is a little quicker and lateral control is maximised.

3.8 CLIMB

At about 300 feet, retract flaps and climb at 57 knots (Normal). There is a significant pitch nose down on flap retraction. Anticipate this and re-trim.

Normal climb is with flaps up and at 57 knots.

If the glider requires a slower tow speed, then the tow may be carried out at a speed not less than 47 knots (NB: a slower speed although possible will cause the engine to overheat). The glider pilot may need to be advised of this.

If the glider is water-ballasted then 5 knots should be added to the normal speeds and turns should be made with shallow angles of bank.

3.8.1.1 Summary of climb speeds

Lift off 35 knots T/O Flap

Initial climb (T/O flap) 52-55 knots T/O Flap

Normal climb 57 knots Clean

High speed climb 62 knots Clean

Slow speed climb 47 knots Clean or T/O Flap

These speeds are Indicated airspeeds (IAS), the actual airspeed will be 2-6 knots greater, this is due to the relatively high angle of incidence of the pitot probe. At the normal tow speed of 57 knots IAS, the actual airspeed is 60 knots. At the descent speed of 85 knots IAS, there is no significant error. Maximum error occurs at 45 knots IAS with landing flap where the actual speed is 6 knots greater.

Maintain a good lookout, particularly under the inner wing, lift it before commencing a turn. Also level the wings occasionally in a turn in order to maintain a satisfactory lookout. Long gentle turns should be avoided where possible. Roll out after every 90 degrees or so.

Towards the top of the climb, check the fuel contents and if necessary change tanks at this stage. Try and maintain a reasonable balance of fuel between tanks.

3.9 DESCENT

At glider release; Stop the climb, acknowledge release by a short turn to the right, whilst retarding the throttle very slowly taking about 40 seconds to reach 1800 rpm. Level acceleration should be allowed to about 95 knots. When the RPM falls past 2200, it is possible to commence descent.

Fly 85 knots and 1800 rpm in descent, this will give a descent rate of approximately 1000 fpm.

Transition to approach configuration and speed should be made at 500 feet as you approach base leg.

NOTE: descent at 1800 rpm is much more conducive to carburettor icing. If icing is apparent or likely then Carb Heat should be used, but make sure the Carb Heat is OFF for final approach and landing.

3.10 LANDING

Landings should be held off to a three point touchdown. A slight bounce may be recovered by a small amount of power. If a significant bounce occurs initiate a go-around. Because of the rough nature of the airfield, two point touchdowns (wheelers) should not be attempted at Dunstable.

After landing, roll straight ahead until at taxi speed, then turn to face the final approach, retract flaps and taxi back to the launch point if clear to do so.

See Appendix 7 - Tail-draggers and crosswind landings.

3.11 WIND LIMITS

A steady wind speed of 25 knots is the maximum permissible, however significant turbulence or gusting associated with lower wind speeds may preclude a safe operation. It is important to remember that it is the tug pilot’s decision to operate or not, if you are uncertain DON’T.

Maximum permissible crosswind is only 10 knots.

3.12 SHUTDOWN

Idle the engine for a short period at 1100 RPM.

Switch ALL electrics OFF, including Anti-collision light and Radio.

Shut-down by closing the throttle and pulling the Mixture control to cut-off.

After the engine stops, switch Magnetos OFF . Master switch OFF.

3.13 REFUELLING

Refuel when the tanks show a quarter full on indicators or before hangaring at the end of the day. Note that Left and Right tanks are graduated slightly differently. The best indication of contents is during climb referring to the three point attitude marks.

Taxi up the ramp to the pumps, ensuring pipeline gantry is in the stowed position. Stop with the propeller over the white line (See 1.15.2 Refuelling). Do NOT use the automatic cut-out on the refuelling nozzle, always hold the trigger and ensure that the nozzle does not bear on the tank neck, they are not very strong.

Record the uplift on the Fuel Record sheet (See 1.17.3)

3.14 HANGARING

When possible the Super Cubs should be positioned on the hill side of the hangar. This is less disruptive to the maintenance area.

Always put the Super Cub in the hangar tail first. Ensure that it is aligned accurately with the yellow marks by the hangar doors, and that the hangar doors are fully open. The tip clearance is not very great.

When in the hangar, ensure that a drip tray is placed under the engine.

Before leaving the hangar, update the Aircraft Status board with details from the Tech. log

3.15 TECHNICAL DATA

3.15.1 Engine Data

Type Lycoming O-360-A4M 180 HP

Max continuous RPM 2700

Max cylinder head temp 260^°C

Oil capacity 8 quarts

Min oil quantity 6 quarts

Oil pressure (idling) 25 psi

Oil pressure (normal) 65-85 psi

Max Oil temp 118^°C

Fuel tank capacity 30 gallons

3.15.2 Aircraft Data

Max take-off weight 790 kgs

Max landing weight 790 kgs

Average Empty weight (G-AVOO & G-BEUA) 490 kgs

Max fuel load (30 gals) 98 kgs

Design load factors +3.8 g to -2.0 g clean config

Limiting airspeeds

V_NE 133 knots

V_NO 106 knots

V_A(Manoeuvring speed) 82 knots

V_FE 74 knots

3.16 FLIGHT MANUAL EXTRACT

The following is a copy of the CAA additional limitations relating to glider towing with the Super Cub. It is for information only, all its requirements are incorporated in this Tug Pilot Manual.

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Figure 11.

4. THE LYCOMING O-360 SERIES ENGINE

4.1 GENERAL

The information contained in this section is provided in order to give each tug pilot a better understanding of the engines he operates.

The Lycoming O-360 series aircraft engine is a four cylinder, wet sump, horizontally opposed, air cooled engine. The cylinders are not directly opposite from one another but are staggered, thus permitting a separate throw on the crankshaft for each connecting rod.

Two variants are currently in use, the O-360-A3A and the O-360-A4M. The A3A engine has a hollow crankshaft whilst the A4M has a solid crankshaft. The A3A engine usually has a restricted rpm band when a metal propeller is fitted. The A4M engine has no such restriction but weighs approximately 3kgs more.

4.2 CYLINDERS

The cylinders are of conventional air-cooled design with two major parts, head and barrel, screwed and shrunk together. The heads are made from an aluminium alloy casting with a fully machined combustion chamber. The cylinder barrel, which is machined from a chrome nickel molybdenum steel forging with deep integral fins, is ground and honed to a specified finish. The valve rocker shaft bearing supports and the rocker box housing are cast integrally with the cylinder head.

The valves are cooled by means of fins which completely surround the area of the exhaust valve and portions of the intake valve. A sodium-cooled rotator exhaust valve is employed on this engine. Bronze valve guides and austenitic chrome nickel steel valve seats are shrunk into the machined recesses in the head.

4.3 VALVE OPERATING MECHANISM

The valve operating mechanism is located on the top side of the engine, facilitating proper lubrication and easy accessibility. The camshaft is located parallel to and above the crank-shaft and operates in aluminium bearings. The camshaft in turn actuates the valves by means of mushroom type hydraulic tappets, which automatically keep the valve clearance at zero. the valve rockers are supported on a full floating steel pin. The valve springs bear against both upper and lower steel seats and are retained on the valve stems by means of split keys.

4.4 CRANKSHAFT

The crankshaft is made from a chrome nickel molybdenum steel forging. All bearing journal surfaces are nitride hardened, and centrifugal sludge removers are provided in the form of sludge tubes at each crankpin journal. These tubes can be easily removed and must be replaced at overhaul of the engine.

4.5 CRANKCASE

The crankcase assembly consists of two reinforced aluminium alloy castings divided vertically at the centreline of the engine and fastened together by means of through bolts and nuts. The mating surfaces of the crankcase are joined without the use of a gasket, and the main bearing bores are machined for use of precision type main bearing inserts.

4.6 OIL SUMP

The oil sump incorporates an oil screen filter, carburettor mounting pad, the intake riser, and the intake pipe connections. The fuel-air mixture passes through the riser, is vaporised by the heated oil in the sump that surrounds the riser. The carburettor mounting pad is located on the bottom of the sump on all models except those incorporating a horizontal draft carburettor. On these models the carburettor mounting pad is located on the rear of the sump.

4.7 CONNECTING RODS

The connecting rods are made in the form of “H” sections from alloy steel forgings. They have replaceable bearing inserts in the crankshaft ends and bronze bushings in the piston ends. The bearing caps on the crankshaft ends of the rods are retained by means of two bolts and nuts through each cap.

4.8 PISTONS

The pistons are machined from an aluminium alloy. Earlier models and all low compression series incorporate two compression rings and one oil regulator ring while later models of the high compression series incorporate three compression rings and one oil regulator ring. The piston pin is of the full floating type with an aluminium plug located in each end to prevent the pin from touching the cylinder wall.

4.9 ACCESSORY HOUSING

The accessory housing is made from an aluminium casting and is fastened to the rear of the crankcase and the top rear of the oil sump. It forms a housing for the oil pump and various accessory drives.

4.10 GEARS

The gears are of the conventional type and are precision machined. They are hardened to ensure long life and satisfactory operating qualities.

4.11 COOLING SYSTEM

The air pressure cooling system is actuated by the forward speed of the aircraft. Baffles are provided to build up air pressure between the cowling and the top of the cylinders, thus forcing the cool air down through the cylinder fins. The air is then exhausted through the rear of the lower cowling.

In our operation it is most important that the baffles and fit of the cowling stay in good condition for efficient cooling. Also, pressure cooled engines can overheat on the ground at idle power, so idling should be kept to a minimum and wherever possible carried out with the aircraft pointing into wind.

4.12 LUBRICATION SYSTEM

The lubrication system is of the pressure wet sump type. The main bearings, connecting rod bearings, camshaft bearings, valve tappets, push rods and crankshaft idler gears are lubricated by positive pressure. Piston pins, gears, cylinder walls and other parts are lubricated by means of oil collectors and sprays. The oil pump, which is located in the accessory housing, draws oil through a drilled passage leading from the oil suction screen located in the sump. The oil from the pump enters the drilled passage in the accessory housing, which feeds the oil to a threaded connection on the rear face of this housing, where a flexible hose leads to an external oil cooler. In the event that cold oil or an obstruction should restrict the flow of oil to the cooler, an oil cooler by-pass valve is fitted. Pressure oil from the cooler returns to a second threaded connection on the accessory housing from which point a drilled passage conducts the oil to the pressure screen, which is contained in a cast chamber located on the accessory housing below the tachometer drive.

The oil pressure screen is provided to filter from the oil any solid particles that may have passed through the suction screen in the sump. After being filtered in the pressure screen chamber, the oil is fed to the pressure relief valve, located in the upper right side of the crankcase in front of the accessory housing.

The oil relief valve regulates the engine oil pressure by allowing excessive oil to return to the sump, while the balance of the pressure oil is fed to the main oil gallery in the right half of the crankcase. During its travel through this main gallery, the oil is distributed by means of separate drilled passages to the main bearings of the crankshaft. The drilled passages to the bearings are located in such a manner as to form an inertia type filter. Thus, only the cleanest oil will be fed to the main bearings. Separate passages from the rear main bearing supply pressure oil to both crankshaft idler gears. Angular holes are drilled through the main bearings to the rod journals where sludge removal tubes are located. Here centrifugal force of the crankshaft removes any heavy sludge that may be present in the oil. Oil from the main oil gallery also flows to the cam and valve gear passages, and is then conducted through branch passages to the hydraulic tappets and camshaft bearings. Oil enters the tappets through indexing holes and travels out through the hollow push rods to the valve mechanism, lubricating the valve rocker bearings and valve stems. Residual oil from the bearings, accessory drives and the rocker boxes is returned by gravity to the sump, where after passing through a screen it is again circulated through the engine. Pressure build-up within the crankcase is held to a minimum by means of a breather located on the accessory housing.

4.13 INDUCTION SYSTEM

The engines used in the tug are equipped with a Marvel-Schebler Model MA-4-5 carburettor. This carburettor is of the single barrel float type, and is equipped with a manual altitude mixture control and an idle cut-off. It is mounted in the standard updraft position on the bottom of the sump. Particularly good distribution of the fuel-air mixture to each cylinder is obtained by the centre zone induction system, which is integral with the oil sump and is submerged in oil, ensuring a more uniform vaporisation of fuel and aiding in cooling the oil in the sump. From the riser the fuel-air mixture is distributed to each cylinder by separate steel intake pipes.

4.14 IGNITION SYSTEM

Dual ignition is furnished on the O-360 series engines by two magnetos. The ignition wiring is so arranged that the left magneto fires the top plugs on the left bank and the bottom plugs on the right bank, while the right magneto fires the top plugs on the right bank and the bottom plugs on the left bank. This arrangement ensures consistent drop-off when switching from both magnetos to either the right or left magneto. The engine firing order is 1-3-2-4.