pj.ladd(at)btinternet.com
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 Posted: Thu Aug 28, 2014 11:07 am Post subject: pumps |
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Hi,
My ex flying partner still flies a Eurostar, the same type we shared but not the same machine. He is a good pilot and meticulous about maintenance. I forwarded our recent posts about pumps to him and this is his reply.
For what its worth.
On another tack John flew me to a local airshow last weekend where we had a flyover of the only two Lancasters still flying.The Canadian one is over her for a month. A once in a lifetime experience
Cheers
Pat
Pat,
Don't know whether you are inclined to forward this to your Kolb list?
As you may know, mine - a 4 year old example - was one of the series of Rotax 912s recommended for a change of fuel pump. Apparently, several of the previous type had failed in service. A replacement was provided free by the then UK Rotax agent and it certainly looked a better-engineered piece of work than its predecessor. That said, the previous one had given me no trouble over 4 years and 300 hours. Nor had the one on a previous Rotax-powered aircraft I had owned over 6 years and 650 hours.
Experience with the new pump belied appearance. I try to stay safe by being attentive to anything about the aircraft which changes - sight, sound or feel - and investigating. The new fuel pump showed big and seemingly random variations in pressure, between 0.2 and 0.4 bar. (The previous pump had given virtually constant readings under all conditions.) It therefore didn't feel "safe".
Matters came to a head when flying over one of the more inhospitable areas of the UK, when the pressure dropped off from its "norm" at just over 0.3 bar to 0.2 bar before recovering several sweaty minutes later.
I raised this with the Rotax agent and with our Light Aircraft Association. The answer was that nothing could be done about it. The new pumps did give variations in pressure and my results were within the specified range. I subsequently borrowed a new-type pump from elsewhere and this gave better results, although still subject to some variation. I have since returned that to its rightful owners and purchased a further new pump. This also gives better results, but still subject to some variation. I may be deluding myself but I think the variability may be diminishing with time. It appears, from talking to others, that the new type fuel pump is just not engineered to very tight tolerances: strange given the strong engineering tradition of where in Europe I assume it comes from.
Not being an engineer or an expert, I cannot advise on what your colleague Dennis Kirby should do! I just add my tale to the request for thoughts.
Regards,
John
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