new vacuum pump

[first taff]

sorry if this is the wrong place to ask , but at our aircrafts last annual the maintainance company replaced our vacuum pump (there was nothing wrong with the original ) as it was over five years old , according to them it was a new easa rule , every one I have spoken too since say they have never heard of this , can someone shed a little light on this matter for me please
thank you in advance

[Solar]

Not sure about the exact EASA aspect of it but recently or club PA28 went through ARC and we had to replace the engine driven pump and the unused electric back up. The engine one I can understand as the hours are recorded but the backup due to time. We suggested that the backup could either be made inop or even removed, but the CAA (don't ask why they were involved) insisted that it had to be removed or replaced, here's the kicker, it's cheaper to renew than remove although the lead time for a replacement is very loooooong.
Though it is never used shirley it would make more sense to mark it inop and in the worst case scenario it could serve as a backup, of course that being logical has no place within EASA thinking.
So much for safety.

[146fixer]

The answer to why your vac pump was changed might be here
http://www.rapcoinc.com/pdf/Service%20letters/Rapco%20Service%20Letter%20RASL-005_Rev_C.pdf

[fujii]

It's not an AD so ask the engineer why.

[peterh337]

I cannot understand the engineering reason for a life limit on a vac pump.

Running hours, definitely, for precautionary replacement purposes (I change mine every ~500hrs or so) but a straight life limit?

[A and C]

This is only a guess but I would think the time limit ( rather than hours run limit) is to allow for the deterioration of the bearings due to lack of use.

[peterh337]

Possibly, but you could say that about the rest of the plane :)

I suspect some of these life limits are to limit liability. If you stick a 5 year life on something, and it kills somebody at 6 years, they cannot possibly sue.

And that would be true even under the US Part 91 regime, where life limits are non-mandatory (unless it's an AD).

Lyco's 12 year crank life limit is one example of this cynical attitude, on which they sidestepped a class action by offering a "free" crank if you send your motor to Lyco for the 12yr overhaul :E

[ericferret]

The UK CAA issued airworthiness communication number 2009/05 entitled

Maintenance of Instrument Vacuum System Components.

This deals with the subject in detail and it begins by citing the loss of a Piper Arrow in 2007 ( a fatal accident) due to a failed vac pump (12 years old 994 hours in service).

If you go to the CAA website airworthiness section and search for

AIRCOM 2009/05

you can read it in detail.

[first taff]

Thank you for your input , it's much appreciated , apparently there was no way of checking the wear to the vanes on the original pump , there is on the new one , they even gave me a gauge to check it with ???:confused: