Advice for A75 Engine - Cylinder

[R985wasp]

I'm flying an A75 that has been trouble-free for 25 years. TSO: 570. It's always had the small oil leak issues around the rocker cover, and the pushrod seal that have been corrected. However, I think I've developed a small crack up in the head near the exhaust port, and it needs to come off for investigation/repair.

However, I'm kind of shocked with how little parts information is out there on the internet lately. I'm probably like most who thought parts would always be available for these little guys.

They are steel cylinders and I would like to repair if possible.

1. Where would you guys suggest I send it for quality work? I've read some questionable things about Gibson, but would like any feedback you can give from personal experience on who has a solid reputation and does good honest work.
2. Should I just get the cylinder repaired, or also replace the piston, valves etc?
3. Money is always an object, but with a low TBO, and pushing 30 years since overhaul, should I just do a complete top?
4. If replacing all four is the decision, are there ANY new Milleniums floating around?

No problems other than the one oil leak on #1 cylinder. All compressions in the 72-75psi range.

Sorry if all these questions have been asked before, but I don't check this board a lot, because my Stearman takes up most of my mx time in the summer. Any and all advice is appreciated!

Thanks

[CptKelly]

Randy,
If it was me, I'd split the case and major the engine. Sure the engine is pretty much bullet proof, but after 30 years... don't you think its really done its job? In aviation, it is always the rule to err on the side of caution. FIX the engine, don't patch it. Just my 2c worth.

Mike

[R985wasp]

Mike,

Thanks for the reply.

However, at 580 TSO and no problems other than a small oil leak in one cylinder. Why would I major the engine? I've been the only one operating the engine since I was 16, and there are no issues with the bottom end.

Keep in mind, I work in the PT6 field for a DOF and am involved in engine related issues 24/7.

My question was more specific to the best shop for cylinder work.

If there were any other problems other than the one small oil leak, I would consider it. However, I see no other valid reason other than the time since it was done.

[Paul Agaliotis]

Randy,
I would find somebody as local as you can get. The cylinders are a pretty basic item. Send the piston and have them check it also.
If it is the A75, some of the inside stuff will be slightly different than the A65. The piston pins will be the small diameter (.859) and can be either the thick wall or thin wall. I believe there is an AD on this. Pistons will be either 3 ring or 5 ring and it will have stellite exhaust valves. Make sure whoever you use knows it is for an A75.
Check with Superior about the cylinders. I heard that they were starting to produce them again, but I don't know if they are acceptable on an A75.
Paul

[brink]

Hello Flier:
I would stay away from the Mellenium units. Sense El-reno went out of business they had lots of parts. I have used Gibson in El-Reno and they do nice work. and I am like you if it ain't broke don't fix it. but you are short out of a top anyway. I run an A-75 in by 7DC conv. also steel cylinders. If you have one use a bore scope, and look her over inside, You can see quite a bit if you take your time. I was at Harbor freight las t week they have a bore scope for under 100 USD. it works fairly well for the price, the darker the enviroment the better. Good luck, A fellow aviator Sunny

[rkittine]

Hi Randy,

Not having enough use (570 hours in 25 years) can actually be a problem as I am sure you realize. The recommended TBO on my C-90-8 is 1,800 or 12 years, which ever comes first. I have had regularly run engines, regularly go over TBO and less used engines, require repairs well before TBO.

I read both good and bad about Gibson and chatted with them on the phone. I recently received a cylinder from them and I was very happy with their work. Guess it can go both ways. I have been told by three shops, that refurbish and also sell new cylinders, that many of the new cylinders are not as good as well maintained and rebuilt used older one. Not sure about that, but my rebuilt Gibson is doing well.

Good luck with it regardless how you proceed.

Ciao - Robert