Steve, When Fred Weick was asked about the safety of the fuel system, he pointed out thet he had made a very thouough study of airplane crashes, due to engine stoppage...and found out the most occured due to fuel starvation, valves turned off, pump failure, etc. His conclusion was ( and I concur) that the header tank made more sense than depending on a fuel pump to supply the engine with fuel.
Now in order to have more than an hour of flying, the wing tanks were added , with a pump to refil the header.He cross fed without a valve so as to keep the airplane in lateral balance, and to prevent a failure from a turned off valve.... The fule pump is quite dependable -if the AI doesn't forget to tighten the cover when performing the annual inspection. Yes the disphragm can fail - and will eventually will, I guess. Easy to change out the quick drain o rings, - just put a tapered plug in the hole where the valve is screwed in. Sure you spill a little 100 ll, but with practice its only about 1/2 cup or so... Electric pumps are more likely to fail, in my opinion...they require elkectricity to operate, plus the other potential problems with a mechanical pump - diaphragm, vcheck valves, hoses, etc. Good idea to replace the old hoses and cover them , etc.......but would be same with electric or mechanical. Only down side I see is a leaking cowl tank.... Than can be a problem, but if maintained properly and repaired when necessary, then I think its the best solution... One might enclose the cowl tank with a fuel tight panel, asnd a drain outside, but I would rather have it open so I can see when the leak first occurs.. Fly Safe - Have Fun Harry .
<<attachment: winmail.dat>>
