Helicopter Engine TBO

I have read some older posts about using HIO-360 variants in RV?s and wondered about the TBO. If for an example, an engine previously used in a helicopter with a TBO of 1500 hrs is ?converted? to IO-360 spec and from what I understand, the internal working parts mostly remain the same, does the TBO remain at 1500 hrs or would it change to 2000 hrs as have most ?O? and IO-360 motors? In other words, if you had a HIO engine with 1100 hrs on it and put it into a RV, when looking at it from a resale point of view, does it have 400 hrs or 900 hrs before recommended overhaul?

maybe

I really don't think the hour difference would make a resale difference.
I think the real resale hit would be a conical vs dynafocal mount.
Robinson engine tbo is 2200 hours, but they run only about 140+ hp for the 0-360. (carb not injected) The Hughes run the injected engine, but you need to change out the sump to get the injector facing forward. I've seen a RV6 with the rear facing injector, fuel flow divided bolted to the firewall, not good.
the good news if you use the hughes engine its all set for a constant speed prop. The TH55 (Army's 269A) used a prop governor as an overspeed device that would kick the throttle if you ran much over 2800RPM (not sure on exact RPM). I would only go helicopter engine if I got a smoking deal on one just due to the different mounts. hope this helps

HIO-360 TBO

I?ve built several engines for RV?s from helicopter engines. I actually prefer them as you don?t have to worry about prop strikes in their history. They use the same parts internally so really there is no difference. I would just put the factory recommended TBO for the fixed wing equivalent and be done with it. There is always some minor exceptions so feel free to get back to me and with the exact engine your considering and I?ll be mor specific. Previous poster?s thoughts on conical mounts or type 2 dynafocal mounts would be the important issue in converting it to fixed wing use.

HIO Conversions

Thanks David. The engine of interest is a HIO-360-A1A with 1300 TTSN. These engines seem to sell a lot cheaper than their fixed wing equivalent as they are that much closer to TBO by helicopter standards.

Just remember that TBO is not applicable to Experimental Amateur Built aircraft.

I recommend anyone worried about absolute TBO hours listen to Mike Busch's EAA seminar here on the subject.

I think Vlad would concur. Fly it regularly and your engine will last much longer than you might think.

Johnny Be Good said:

These engines seem to sell a lot cheaper than their fixed wing equivalent as they are that much closer to TBO by helicopter standards.

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One of the reasons for the lower TBO and the lower resale value is because helicopter engines, particularly in working helicopters doing external load work, are spending a whole lot of their lives near max output capacity and with temperatures near redline. They often lead a hard life, which is reflected in their reduced life expectancy.

From a pricing perspective, consider the helicopter operator sees that engine as being at 80+% of its life, while the same hours on a fixed wing airplane would have it at about 60% of its life. That makes for a big price differential.

HIO-360-A1A

Johnny Be Good said:

Thanks David. The engine of interest is a HIO-360-A1A with 1300 TTSN. These engines seem to sell a lot cheaper than their fixed wing equivalent as they are that much closer to TBO by helicopter standards.

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The book says it has conical mounts with Bendix fuel injection. It?s listed as 8.7 compression ratio which means it?s an angle valve. I would be curious as to which Bendix Fuel Servo it utilizes as some helicopter engines use a strange altitude compensating type. Sounds like a good candidate but I would probably do a fresh top end overhaul and then you?ll have the opportunity to do a through inspection of the internals. Make sure you have the correct motor mount to accommodate the conical case. Based on what your sharing I wouldn?t be afraid of it but as with all Lycoming?s, if they have been sitting idle for extended periods of time corrosion is always a concern.

Helicopter Engines

Thanks for the replies.

With regard to the necessity of doing an overhaul at TBO, I appreciate that it is not a requirement but it does impact the resale value of an airplane. If one is going to keep his or her airplane indefinitely and trust it to keep running then it is a non-issue but it probably will be for a prospective buyer.

I started this thread because there is an engine currently advertised elsewhere that seems like a good deal. I am not going to buy it as I am not ready to make that decision but if some of you more knowledgeable folks have a look at the listing I would appreciate further comments. Thanks.