Bringing the O-470K Back to Life

Rob58

Rob58

Moderator
Happy New Year! As I continue on my -2 restoration project I’m trying to determine if a major overhaul is the only option for the engine. It has been 40 years since the engine ran. Both engine and airframe have about 1150 hours. It burned very little oil and ran smooth. Compression was good at the last annual, but 40 years have past with no maintenance. My plan has always been to have the engine majored, but with the continued cost increases of a quality major overhaul I wanted to explore other options. Any thoughts about this? Thanks, Rob
 
Forty years? That's a lot of collected dust. Did the engine go through any kind of preservation process after it's last run? If not, I would sure like to know how well the steel parts held up after all that time. I'm not familiar with the Cont., but I have an O-435-A which developed rust, pitting in all the wrong places. Again, not being familiar with your engine, but 1150 hrs. sounds like it's getting up there. I rebuilt my 14-19, and the engine was overhauled, too. If you don't choose to o/h, do all you can to be sure of what have inside the case. Tom Robinson
 
Unfortunately I took no action to preserve or prepare the engine for long-term storage. The only positive note would be the fact that the engine has been stored in a very dry climate. However your point is well taken and I would never try to bring the engine back to life without a complete teardown and inspection. At this point I am trying to weigh the options of a field overhaul versus a factory overhaul. Probably the biggest dilemma is finding a high-quality, trustworthy engine shop as I have no experience dealing with these guys. --Rob
 
Thanks for the good tips Larry. You make a good point: what level of repair defines a "major" overhaul? Maybe there is some benchmark for this, but I don't know what it is. I don't think I will be able to start the engine unless I can find a test stand somewhere since I am already in the process of the teardown, however I like the idea of your lubrication process before taking the engine apart. --Rob
 
So here's another opinion-
You have over 1100 hours on a 1500 tbo engine, and while tbo is a reference number for part 91 flying, it is still indicative of engine life expectancy. (This from a person who is flying behind a 1500 hrs smoh on my Franklin - a 1200 hr tbo engine). Your engine hasn't started in 40 years and hasn't been preserved in that time.
I guess if you can get an IA to sign off an annual, you can fly it, but is that really a wise thing to do since your can't really see the potential failure points in the engine?
So I suggest that you don't screw around with all the things Blimpy suggested, but tear it down now. Once it is torn down, you have to NDT and measure the parts anyway before it goes back together, so don't waste time...unless you are like me who can stretch an annual out for 6 months and just enjoy the process. If you find a mechanic who will rebuild it, without doing the necessary NDT/measurements- don't! Engine failure is not fun!
 
Good input Larry. Safety remains my number one objective... lot's of kids, grandkids and friends will be riding along with me... no cost is too great to insure a safe ride. I think my biggest challenge is to find the right shop to do the overhaul. --Rob
 
Robert, this article is a gem and resolves a lot of the ambiguities associated with the terminology. Points right to FAR 43.2 as the source of authority defining the term "overhaul". Thanks very much!
 
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