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Os 32 issue


scott finnie
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So was out flying today and whilst at around 100 ft high my helicopter engine changed not then started bogging down. I didn't get the chance to land before it had cut out though successful autorotate followed. I have managed to start it since but it only idles for a few seconds. Now it won't start at all. Fuel is clean and new, new plug and carbon looking clean.

Any ideas?

Thanks
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Could be anything from blown plug to seized conrod.

I would check the plug in there is still working irrespective of its age, then if you have fuel and compression it has to fire at the very least. If its not too difficult removing the engine backplate for a quick peak inside might be worth while just to confirm all is well. I would have thought you could remove it without having to take the engine out of the heli.

Other things to check are the usual debris in carb or split pipe sort of stuff. Hopefully its not the rod and it was just protesting that it either got too hot or went lean for some reason

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Scott, a sudden change as you describe is usually something taken in so clean the needle and flush the inlet

or it is a pressure leak from one of the pipes or joints at the pipes or tanks

there will not be copious amounts of fuel flooding from a pressure leak

It is just a pressure drop in the supply when the motor gets to high revs and interupts the pressure of supply

New fuel pipe is a lot cheaper than a heli

Edited By Denis Watkins on 22/06/2017 14:39:50

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Hi Scott,

I had the same symptoms on one of my OS32s - after bit of fettling and frustration, I noticed a much reduced performance, then only ran for short periods and eventually couldn't get it to run at all, so I sent it to Just Engines who stripped it and found the piston liner had deteriorated and was moving with the piston. Engine was U/S.

I sincerely hope this is not the case with your engine but it might be worth sending it to them to find out.

Fingers crossed for you

Rob

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Posted by David P Williams on 22/06/2017 14:59:43:

When I've had similar problems on helis it has usually been that the clunk tubing has deteriorated and split so engine runs OK with full tank then goes lean as the level falls. Clunk tubing always seems to rot on my helis, but not in my fixed wing models - any ideas why?

Yes David, all of your fuel pipes are a compromise of silicone against destructive agents of fuel and have a life span, but your supply pipes transfer fuel through a small surface area within the pipe

The clunk pipe spends more time submerged in fuel, and is coated in fuel over a much greater surface area, the outside of the pipe as well as within, so deterioration is greatly increased

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A common fault with the OS 32  SX ABC engines was the chrome coming off the cylinder wall. You heli engine should be a ringed engine and I don't think they suffer the same. If its a current engine then your problem may be elsewere. A quick look in the cylinder will confirm if it's the problem. Four cylinder  head bolts and the head is off. Look for brass coloured marks near top of cylinder.The symptoms are sudden loss of power / compression when warm . If that's your problem then engine is scrap as a new ABC piston liner set is over £100 ! As others have said check all the plumbing for leaks including the pipe that goes through the tank bung to clunk especially if it's a brass tube.

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If it's an ABC engine, there's a possibility that a liner/piston for an ASP 32 might fit - I know that many OS/ASP 46 parts are interchangeable for example...they are around £27 for the pair. You will probably need a set of bearings (which might have been the cause of the damage if they have started to disintegrate and send fragments through the ports into the cylinder) but these are very cheap from a normal bearing supplier.

You could call Just Engines to check - or the good doctor (engine) might know...

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Posted by Braddock, VC on 23/06/2017 08:40:21:

Or you might want to get in touch with the importers, Ripmax, and ask them how long thje plating should remain on the liner.

I did this with both a 46 Fx and a 10 Fp and the liners and pistons were change FOC except for the postage up to them.

It might be worth a try but if engine is not a current model I don't think Ripmax will be interested and the 32 doesn't show in the current OS list .I had a couple of the SX repaired by RM some years ago and they did an excellent job; however the new cylinder shed the chrome within a couple of hours of use. The plating is poor quality done cheaper in Taiwan and not up to the Japanese quality. But why do ASP etc not have the same problem ? When this was happening a Forumite claimed to have had  a cylinder checked by a metallurgist . They reported finding what could only be a fingerprint on the brass liner underneath the chrome ! That might be true but the fact remains that only OS have a record of this happening on a regular basis mainly with the 32sx series . A couple of other models were affected I believe .

The OS 32 Heli engine  was a ringed engine with parallel bore and doesn't seem to suffer the same Burgess not as powerful. You could replace with the AX 35 as OS should have sorted the problem by now and I believe that the AX will fit on the same mount but do check.

The ASP cylinder will not fit the OS as checked  out back in 1990's. 

Good luck with replacement .

Edited By Engine Doctor on 23/06/2017 09:33:15

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OS have to use a coating other than chrome because under Japanese law they cannot stock the quantity of chrome needed for their production. The replacement barrels and pistons are supposed to be FOC for life because of this problem. I have sent a couple of 25FXs back to the importer a few times and they have even replaced the bearings FOC. Don`t know if this still applies but worth a call to Ripmax.

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Posted by Martin Whybrow on 24/06/2017 01:28:53:

What law prevents them from holding stocks of chromium?

Could be this:

In addition, the legislative environment has stabilized as well. While there may be new regulations to come from the Occupational Safety and Health Administration governing hexavalent chromium emissions in plating facilities and workers' exposure levels, and Japan and the Scandinavian countries are reported to have comprehensive bans on hexavalent chromium under consideration, there appear to be no near-term legislative initiatives that will significantly affect the ability of domestic chrome platers to function profitably.

That was from 2003, so the proposed bans may be in by now.

Source: **LINK**

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