Warbird Information Exchange

Can anyone comment on the overhaul requirement for the -1340 as it applies to Part 91 non-commercial use? Is it strictly a mfr recommended time, or regulatory?

All I have found so far is a note on Covington's website that lists the recommended TBO for the -985 and -1340 at 1600 for non-Ag use. The same note mentions an AD on the R-985 at 1600 hrs that is significant enough cost wise that you might as well do the full overhaul. Is that AD strictly for the -985 or are there any similar ADs for the -1340?

As far as I know there os no TBO for the 1340, but the military did it if the oil use went over 1 gal per hour. 1600 is a reasonable figure.

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If you follow Mike Busch, "The Savvy Aviator", through the EAA's "Sport Aviation" magazine, you may have seen a recent article of his which dispels overhaul requirement myths. He is a huge proponent of on-condition maintenance. That said, get a copy and read it for yourself and decide what's most appropriate for you and your engine.

Ken

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"Take care of the little things and the big things will take care of themselves."

Oil samples at regular intervals can help determine engine health and TBO is greatly affected by how the plane is operated but you might send an oil sample to Covington in Oklahoma and talk to them. They are always happy to talk to their customers and give good advice. Anytime I have a 1340 or 985 question, I call right away. 918) 756-8320

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The more I learn about aircraft, the more I realize I still have to learn.

I will also give Covington high marks. When you do decide to do your overhaul, they actually encourage you to spend the day with them while they tear your engine down, so you can see what you have. It is a big, clean shop and they do a lot of 1340's. They will give you a first class tour of the place as well.

One thing to consider if you are deciding to push the limits on TBO. As parts wear, the tolerances naturally increase, so wear increases exponentially. You will likely replace everything if you run it too long. If your cam and crank are within specs, they can be chromed and reground. If they wear beyond max, you will replace them both.

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Rob C

Historically, the claim of consensus has been the first refuge of scoundrels; it is a way to avoid debate by claiming that the matter is already settled. “

– Michael Crichton

Thanks for the info all!


That is a good point.....sounds like oil consumption probably is a pretty good guide for when it is time to overhaul.

Not always, your engine will talk to you if you listen to it. Carl's engine used very little oil, but we started to feel a new vibration, compression tests showed nothing out of the normal, oil analysis were clean, we had 1200hrs on the engine and decided to go ahead and overhaul it. turns out there were 2 cylinders that had started to crack and a bad rod. Use your judgement, we went by a change that was different from the norm and it saved use from a possible engine failure.

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Matt Gunsch, A&P, IA, Warbird maint and restorations
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Good comments. 1100 hrs seems a pretty common number from our experience.....

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Tom N

RobC has hit the nail right on the head.
Going past 1200 hrs. can wind up costing you much more for the overhaul than the extra couple of hundred hours are worth.
Replacing a cam drum $3500+
Replacing a crankshaft $6,000+
A good night's sleep.........Priceless!

Just my 2 cents worth, I hope it helps.

That is some good food for thought.

Particularly since I have no idea about the history of the engine.

My question involves an aircraft for sale.....price is appropriately discounted (assuming there is no other issues with the airframe) to account for a future engine change, (the engine is just under 1600 hrs). I was originally thinking it might be worth it to buy the plane and put a hundred hrs on it before the changeout, but based on this, I'm thinking it might be better to change it out right away.

I haven't explored the idea far enough to ask the current owner about oil consumption.

Oil consumption is from either the rings or valve guides and is not a reliable indicator of the health of the bottom end of the engine. Hopefully you don't overhaul the entire engine because of one leaky cylinder!

Always do a compression check

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Always do a compression check correctly, if you have to ask what the correct way is, read up on it,
http://rgl.faa.gov/Regulatory_and_Guida ... r%2008.pdf page 7-8

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Matt Gunsch, A&P, IA, Warbird maint and restorations
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Back thru the early '90s when I worked on a couple of Air Tractors (AT-301s w/ R-1340s) we always went by 1200 hrs. I knew of one ag operator who used 800 - 900 hrs. almost as if it were mandatory. Another one went to 1500 hrs with no problem at O/H, but he was probably just lucky.