[Bill McCarthy]

I wouldn’t even contemplate an engine that had any chance of raiding my wallet - such as Lycoming, Rotax etc. There is a lot to be said for the good old wheezy VW ( I keep saying it) . There were nearly 30 million of them made, they are just as reliable, simple, cheap as chips, easy to maintain, and you can work on them with the confidence that in the event of a major fault, you can bin it and get another !

[Tac_R]

Cockney Steve;

That's a fair point, but for my part I see it as another pro-active maintenance tool (or if you like, just a comfort blanket!), along with oil consumption, filter inspections, compression checks and borescope inspections etc. to asses the relative wear of the engine, its components and hopefully pre-emptively identify any source of concern for an early warning of any unusual / abnormal wear - again, with the caveat of Trend Analysis. I certainly wouldn't (and don't) worry over an extra £2 p/hr considering the other costs, incurred or potential.

Each to their own, though

Regards,

David

[A4 Pacific]

Though my engine is nowhere near being run ‘on condition’, I too am a big fan of SOAP analysis. Yes it adds a few quid to the cost of my oil change. But I think of it as not just a way of monitoring the health of my engine for maintenance purposes, but as an additional (cheap) measure to reduce the chances of my engine going bang when I really, really wouldn’t want it to! To me the minimal expense feels like reasonable value. It’s as much a safety issue as a maintenance one, and I’m always happy to spend money on safety.

As has been said. Each to their own.

[CloudHound]

Bill, if you can supply me a 180 hp VeeDub aero engine I'll buy 10

[riverrock]

you can buy 220hp engines: https://www.cbperformance.com/product-p/1187.htm
A wee reduction gear and I'm sure you'd be good to go

[Wabash]

The one to be careful of is buying airframe for a premium because of a recently overhauled engine only to find a few flying hours later it goes boom. I suspect i would much prefer buying a high timer and then when time comes I can choose who I think can be trusted to rebuild the engine. From a classic car engine point of view I had good success from personally recommended retired lifetime engine rebuilder old boy types who do it for love in a dark dingey oily shed full of tools. Swanky clinically clean engine shops with receptionists lots of young employees and Astons in the car park in locations with high land values - I would be suspicious of where all my money is going etc...

[Arclite01]

This is one of my pistons 5 hours after a factory overhaul...................

I'd take an 'on condition' with a good history and a pre-inspection every time. A factory overhaul cost a bomb and got me nothing in return.

Guess what - they had no interest and said I had probably used the wrong fuel - yeah right !!

Arc

[Charles Hunt]

That is horrible.

What would it take to cause that - much too weak a mixture allowing temperatures to rise and melting the piston?

[Flying_john]

That must have shown up on an EGT, or CHT gauge, assuming they were fitted , or poor running symptoms.

To generate the required temp 650 degrees+ the mixture would have to be very very lean.

Or - oil is getting past all the rings or through the valve guides and set on fire, but not enough carbon around on the piston for that.

[Arclite01]

The Engine manufacturers said they suspected contaminated fuel but that was simply not true.

My engineer said that he suspected they would never admit liability - be it either parts or labour as the potential to open themselves up to all sorts of litigation was huge. Easier to blame the operator and virtually impossible to prove otherwise.

The engine seized as a result of the piston issue. I had a CHT but not on this cylinder (typical !) - there was no indication of an issue until some oil appeared on the canopy and then it ran rough. I shut it down at that point and then did a glide approach back to the airfield. PAN call and then cancelled once I landed.

Rebuild cost £7K - front cylinders and majority of engine unaffected due to quick shutdown. That on top of a £4K overhaul beforehand !! (ouch)

Arc

[Aeronca Alan]

That on top of a £4K overhaul beforehand !!

£4K? What engine is it?

[oldbiggincfi]

This is one of my pistons 5 hours after a factory overhaul...................

I'd take an 'on condition' with a good history and a pre-inspection every time. A factory overhaul cost a bomb and got me nothing in return.

Guess what - they had no interest and said I had probably used the wrong fuel - yeah right !!

Arc

That looks like the spark plug was a bit close !

[Charles Hunt]

If it was fuel, what did the other pistons look like?

[Wabash]

Don't have much direct experience of aero engine full overhaul but £4K doesnt seem a right lot depending on how many new parts are needed (on presumption parts/ labour is higher than some automotive rates?) As comparison very rough ballpark full overhaul from well known companies with good rep and many prices below are 5 to 10 year ago:

Merlin overhaul circa £120k?
P&W 985 9 cyl £35K
Aston 6 pots at £30k and up (10k for a new block alone)
Aston v8 big bore rebuild £65k rip off territory
Jag 6 pots £6k and up
Spit 4 pot £2k (1k labour, 700 new parts, no skimping ) old boy in shed

Did have a stag which prior owner 10 year ago spent £1k on v8 overhaul with just £100 in new parts . It worked OK but I don't think overhaul is the term more like bare minimum which subsequent inspections revealed. But it didn't blow up after 20k miles so you can get away with it.. sometimes

[Wabash]

The other thing of note is that most of these failures would possibly revealed them selves if the engine was run in by the overhaul shop -not sure they do that but 2 Aston rebuilders I visited (window shopping only )had engine test cells and they do this and you get the data etc including hp curves so they ain't idling them they're stressing them in as well and it explains some of there rebuild costs! Whereas it looks like you aero guys get to be test dummy with engine whilst in flight

There can be nuances to running in: my old boy in shed told me to run in my spit 4 pot by giving plenty of revs DON'T idle it because the pushrod tappets need to spin round as they go up down on cams otherwise you can get flat spots developing on wearing surfaces on new engine , so it got plenty of revving and it was incredibly tight to start and turn over I recon they must have run them in at factory using an electric motor, but 20k miles later and many hours at 4000rpm on motorways it appears to be a good rebuild!