Nimbusgb wrote:
The bad news …..
A Lycoming document Lycoming pdf states that anything that damages the prop, whether the engine is running or not demands a teardown and shock test on the engine!
Not exactly. This document is, as any other SB, a recommendation from the manufacturer. I would not dismantle an engine just because one propeller blade has been damaged by an impact with the engine off.
Peter wrote:
I can’t see how it could be airborne or even during taxi. There are no airborne bricks, nor are there bricks floating a few inches above the ground.
Good point. This is the opinion of the assessors not mine. They sent a pair of blokes out to inspect and their opinion is what will be communicated to the insurers and to which the insurers will base their opinion on no doubt. I’m still of the opinion that it was a tow bar.
Coolhand wrote:
This document is, as any other SB, a recommendation from the manufacturer. I would not dismantle an engine just because one propeller blade has been damaged by an impact with the engine off.
So where do I stand with the maintenance organisation and future insurance? If I refuse to have the engine shockloaded they may well simply not sign it off as fit to fly and the insurers may well refuse to insure it. The prop is beyond repair I’m pretty certain, that implies one hell of a bang, ground, airborne, engine running or not. Last thing I want is to take up gliding at low level over Chester!
Several people have said ‘classic castoring nosewheel towbar strike’ Others say rocks/stones/debris.
So where do I stand with the maintenance organisation and future insurance?
If you can get a release to service then by definition it is airworthy, and insurance is not an issue (some would argue to still make a full disclosure to cover yourself).
If you can’t get a release to service then the plane is worth scrap value. The engine will have a core value to any overhaul shop (highly unlikely there is any damage anyway). The plane could be broken for parts; that can sometimes make good money (I know of a few) but it is a long drawn out job and in the meantime it takes up a lot of space.
As regards the hazard, I don’t think anybody will be able to dictate your attitude to risk. I certainly wouldn’t tell you what to do. For 100% sure many people would change the prop and fly with it (and many would sell it ASAP without disclosure, hey ho…). In the homebuilt world, some just change the prop after way worse damage than this, in terms of risk to the crankshaft and the engine mounting frame.
If I was forced to fly behind that engine, I would
The prop is IMHO deffo beyond repair, but I could be wrong 
Several people have said ‘classic castoring nosewheel towbar strike’ Others say rocks/stones/debris.
It doesn’t look like a stone, from the impression in the metal. I have seen loads of stone dings and they don’t have any specific impression like you have. And stones big enough to do this are unlikely to be sucked up by the prop (but it is possible). What is most likely IMHO is that somebody either hit a towbar or taxied into something else on the ground e.g. a concrete tiedown block. I have come very close to those myself but luckily spotted them. Or taxied into a tug – those are mostly steel.
ONE other chance could be to find a good used engine and prop and get it installed. The airplane itself is a great type you will enjoy flying.
Peter wrote:
The engine will have a core value to any overhaul shop (highly unlikely there is any damage anyway)
The O-320 has no movable crankshaft counterweights, so if crankshaft front flange runs true the item I’d be most concerned about is the crankshaft gear retaining bolt. These have been known to fail as a result of a prop strike. It’s number nine on the generic Lycoming list of things to check.
Regardless of what happens to this plane, just to make the point, there is almost zero chance that this engine won’t fly again.
Nimbusgb wrote:
Dorset company about £8k for shockload and replacement of shock loaded parts.
That is about the first reasonable price I’ve read in this thread. 8k is realistic I’d say, particularly if it comes with replacement of parts.
Did you ask that company if they possibly have a replacement engine? Sometimes engine shops have engines in stock. We had a case like that recently with a towbar strike where the engine shop offered a mid time engine (roughly same time as the one they handed in) in exchange for very slightly more. The whole exchange took 3 days once agreed upon.
Prop, depending on what the insurance will pay, I’d look around for a 2nd hand one. Good chance that there will be one. Did you talk to a prop shop already (also to find out whether your prop is repairable?) They might have a compatible one or know where to source one from.
Incidently, what is the EXACT Prop Type you have?
You were very unlucky, most of us never get anywhere close to this kind of situation (thankfully and knock on wood). I am sure that once you get this sorted and can fly your plane, you will soon get over these initial problems and enjoy flying your own plane.
Prop is McCauley IC172/BTM7359
I believe there is a Sensenich replacement (STC details unknown at the moment ) that is a little better, a little cheaper and that would take the 160 hp upgrade it it were done. That would need a new backing plate and spinner.
Got a quote to rebuild my engine for £14k odd ( genuine Lycoming pots and pistons ) . With a new prop that might be worth doing.
Does a full rebuild effectively 0 time the engine? Is it going to add say 15k to the value of my collection of parts?
IMHO it makes no difference whether the engine logbook starts at zero, to any subsequent owner with a brain. It is a technicality. What matters far more is the reputation of the engine shop that did the work.
BTW you don’t need new cylinders for a shock load inspection. The process is basically
Cylinders can go back on as-is, but if the pistons are changed then the cylinders need to be re-honed at least.
Not sure if @michael still posts here but he will know the rules.
Anybody offering you something with new pots is trying to make money out of you.
You should discuss the level of overhaul being quoted with the people quoting the work. The word rebuild does not have a strict definition within the regulations. The regulatory definition of an overhaul is only (to paraphrase) that the engine is disassembled, inspected and measured in detail, found and/or corrected to be within service limits in all regards, and reassembled. Obviously the regulations cannot force people to go further than service limits but equally obviously most want to go further than that in every regard, particularly when the customer is paying for labor. The ideal is that everything is brought to new limits, not service limits. If you buy new cylinders, as most do today, that certainly brings the top end to new limits. The rest is between you and the overhaul shop, and (getting into detail) sometimes if a component is well within service limits, perhaps barely outside of new limits, it can be safely reused for another overhaul cycle. The intent for your engine would typically be to make the engine ready for another 2000 hrs, the time between overhauls for an O-320.
A point of interest is whether and/or how many times the engine has been overhauled. An engine that has not been overhauled before is termed a ‘first run’ engine. The more times it is overhauled, the more fatigue may become an issue, as opposed to simple, measureable wear, with aluminum parts like the crankcase being of foremost interest. Also steel gears because these that are very often inspected for surface fatigue on the faces of the teeth and reused if they are OK. This is where the judgement and experience of the overhaul shop becomes valuable.
When buying a low-ish value plane (I have two) with a low time since overhaul engine, a smart buyer looks at the overhaul records in detail before deciding how much it increases the value of the plane.
Hope that is helpful.
