engine indications
 

Not sure if this is in the correct area so advise if not!

I have an aero engine for a well known light single. since overhaul it has been constantly going over the red line and will only just maintain level flight at around 50rpm below red line.

I think it is not safe to be doing this but others in the industry say its fine. However why do we have red lines painted on things (oil temp/pressure etc) if it means nothing? Surely the mountings for the engine can only take a certain torque?

Answers on a postcard please - should the aircraft be grounded?

Ta

Could do with a little more information, really, Jelly. What aircraft is it? Is the propeller fixed pitch or controllable? Was it overhauled at the same time as the engine? Does the engine overspeed during ground running as well?

Alot more info req'd.

Definitly not safe if you need 50 rpm below max to maintain steady flight.

It sounds like a variable prop, was it overhauled at same time?. You need to do some instrument calibration.

Could be a number of things...................Ground it before it kills someone.

It is a fixed pitch prop. Prop has just been overhauled too and that has made no difference.

A new rpm indicator has been fitted but again no change. I could not cay about calibration but with a new instrument it seems pretty pointless?

As regards ground running - on take off roll it is upto the red line but then in climb it creeps into it and levelling off... 150 - 200 revs over the limit.

I'm suspicious of the prop. What does the maintenance organisation say about it? Is it definitely the same item (part and serial number) as was sent away for overhaul? Can they ask an owner of the same aircraft type if they can fit his/her prop for comparison purposes. Two hours labour charge at the most.

What aeroplane is it, anyway?

Props have been exchanged with other aircraft of the same type, c152 and this problem is still occuring. It never di it before the engine overhaul but when the same prop was fitted and others with the "new" engine... the overspeed appeared

Hmmm... a bit of a mystery, to be sure. Why not contact the engine overhaul facility for their opinion? I'd suggest you get the rpm checked with a hand-held electronic prop tach first, even though the mechanical tachometer has been replaced.

Forgot to say that it has been checked by an electronic prop tacho and that confirms what the mechanical one indicates.

I am of the opinion that it should be grounded before it causes too much damage but the powers that be say fly it!?

I'm right out of ideas. The overhaul facility will have their test run figures on file and I think they should be your (or your AMO/employer's) next contact. You're right - the aircraft should be grounded: over-revving causes engine damage and if you're lucky it'll show up in the oil filter before the AIB get involved. It'll be expensive, either way...

check the length ot the blades

First of all - ground it. If you superiors disagree give the CAA a call for backup. I'm sure they'll insist it be grounded.

Secondly, get on to the engine overhaul facility and get a copy of the work pack. Everything they did to that engine will be documented. Take it to an independent maintenance organisation and have them go through it and ensure everything is in order, correct parts used etc.

Limits are there for a reason - it usually is the case that it's fine to operate above those limits, but this is for a transient period only. To routinely operate above the limits is a definate no-no.