Dear Tuggie,

I have agreed with Andrew R and Robin M that we should send out the occasional letter or e-mail, such as this, the point of which is not to criticise anyone, more to remind all of what we believe is best practice, and where it sometimes falls a little short.  Our operation is set up first and foremost to be as safe as it can reasonably be, followed by being efficient.  With the spiraling cost of AVGAS (currently around £1.50/lt) and maintenance, this becomes ever more important.  Although we flirted with the idea of wearing parachutes in tugs, we don't, and so we rely totally on the good airworthiness standards of our tugs (thanks Aiden). However, there is much we do, and can do, to help minimize wear and tear and to promote efficiency.

Generally, the operation runs very well and, in comparison to other clubs I have visited over the years, I believe our operation is probably the best.  However, we cannot be complacent, particularly at such a busy club (second largest in the UK) within Luton's Class D airspace) and with a not over-large airfield.

1. Hangar rash

There have been quite a few occasions over the past couple of years where minor/not so minor damage has been caused getting the tugs in and out of the hangar.  Recent events are the chipped, new, canopy on 'CC (oil flap left open when the canopy is slid forward = crunch - this also happened on 'CA), and the broken wing tip hoop on 'UA (again), together with paint transfer from one tug/motor glider to another.  It has probably happened to all of us, I suspect at the end of a long day when we are tired and few helpers are around. These events are avoidable with care, so please take care. (These events particularly p**s off AW - additional avoidable work).

2. Tug order of use

Aiden has reverted to allocating a preferred order of use form the tugs.  I know this cannot always be followed, for example when 'UA or 'CA is No1 and the duty tuggie isn't rated, but generally Aiden does this for maintenance planning.  I know it is a real pain to extract to No.1 tug for the back of the hangar but please try to do so (Hangar rash issues?), carefully.  If the tugs get out of sequence then we run the possibility of more than the minimum number being unavailable, probably on that mega day, and also increasing AW's workload. (As an aside, I think we do very well on tug availability over the year, considering what we demand of them.  Most maintenance organisations I have visited would not contemplate looking after 6 aircraft with only one engineer.) 

3. Engine management

From an engineering perspective, the correct engine starting technique is vital to assist with the reliability and longevity of the Lycomings fitted in the tugs.  Two issues. 

a) Starting from cold. 

As none of the engines in the fleet have pre-oilers installed, oil pressure, and hence the circulation of oil to the bearings, only occurs once the engine is running. Hence, those first few seconds are vitally important if excessive wear is to be avoided. This is particularly relevant if the tug hasn't been used for a period as the oil covering the wearing surfaces will have drained down. On quite a few occasions I have seen cold engines running up to high RPM immediately after a cold start, before being brought back to idle. This causes unnecessary wear to the rotating components, which is accumulative. Such wear cannot be totally eliminated, but it can be minimised by making sure the throttle is set to idle before starting'.

b) Starting a hot engine

I recently witnessed one of our tuggies trying to start a hot engine, cranking the reluctant engine continuously for an extended period. It is not unknown for starter motors/associated wiring to catch fire under these circumstances. Please, if an engine will not start after 8 or so compressions, pause, and give the motor a chance to cool down and you a chance to think. The problem is usually that the mixture is wrong (too rich or weak) and pausing often allows this to change. The technique that usually works is to pump the throttle once and set it to idle, leave the mixture at ICO and crank the engine. As soon as it fires, move the mixture to full rich.

4.All out

The call "all out" from the Dunstable Radio is not actually the trigger for tuggies to apply full power. It merely signifies that the glider pilot is ready to get moving and full power should only be smoothly applied when the rope is actually tight.. Quite often I have seen power applied with a significant bow in the rope which, of course, leads to a snatch take-up. Whilst this is unlikely to break the tug or glider, it does apply a significant load to the weak links and probably precipitates their premature failure. The cost of a new staple is immaterial, but the hassle factor on a busy day is very frustrating.

5. Climbout

I've had a few reports this year from glider pilot's re. towing speed. As you all know, each tug has an optimum towing speed (yellow mark on the ASI), which may be modified, of course, when towing water ballasted gliders with high wing loading or, for example, vintage gliders. Observations have been made by a few glider pilots about towing too slow as well as too fast, and speed that varies a bit too much. The easiest way to control the speed is to hold the aircraft at the attitude which gives the target speed, rather than 'chase' the speed on the ASI. If the speed does get away from you, please make slow corrective actions, particularly near the ground.

6. Descent planning 

It is quite apparent that on more than a few occasions the tug arrives back from a tow at 500 ft some distance from the field. Just by way of a reminder, the ideal situation after a tow is to arrive at 500 ft aal somewhere close to the top of base leg, in time to slow up etc, after the standard descent (RPM/speed appropriate to the tug and 1,000 fpm RoD). This is not always possible if, for instance, you tow out further than normal through sink. It is preferable to reduce the RoD on the way back under these circumstances to achieve 500 ft at the ideal position, rather than arrive at 500 ft a mile from the airfield and then power it home. This exposes the tug to an increased risk, should the engine fail, showers our near neighbours with extra noise, and burns more fuel.

7. Landing

Tuggies who are Cub rated know all about the fully held off landing, in the three point attitude, and how readily it will bounce on this field given the slightest chance if you attempt to touch down above stall speed. Even then, it may bounce if you hit a bump (honest, not just an excuse for my Cub landings). The Robins, on the other hand, are very reluctant to bounce due to their CG being forward of the MLG. This pitches the aircraft nose down as the main wheels hit the grass, reducing the lift on the wing, hence no bounce. This of course means that if the aircraft is fast, it will stay on the ground, hammering the landing gear. I won't pass on Aiden's comments whenever he sees this, you can probably guess. It does cause extra wear on the expensive landing gear units, so please practice fully held off landings. Its not too difficult, particularly if height/speed are appropriate for the conditions of the day at the start of base leg.

And finally,

8. Taxying

Continuing the theme of wearing out landing gear legs, we all know that it is, in places, a rough field. The Robin gear is good at smoothing out most of these bumps from the pilot's perspective. I know it’s tempting when we are busy, large grid etc, but please give the tugs an easy time by not taxying too fast

Many thanks if you have read this far. As I said at the beginning, this is not a criticism of any one tuggie, as we all generally perform to a high standard, more a summary of observation/comments etc, made over the last year or so.

Finally, again, thanks for the continuing effort in cleaning the tugs after use. Unfortunately, 'UA is a bit left out owing to the difficulty in cleaning its high wing. Maybe we can organise a cleaning session on a slack day?

Peter Claiden

DCTP