JetCat PHT3 problem in AirStar Hughes 500e.
 

Anyone on here flying one of these? If so please respond to my problem if you can help.

Hi guys,


I was flying my big Hughes this morning and suffered what I thought was a power loss. After landing safely I realised that the rotor speed was simply not as high as it should be. The turbine was still running within and upto all the limits, so it was just the rotor not getting up to speed. After a close look I found the clutch bell was slipping on the pinion gear shaft (this is the pinion and shaft that runs on the main gear). I tightened this and was confident that the problem had been solved. Alas, it did not - so whilst the clutch bell may have been slipping, it was not the main cause.


I have checked the one way bearings on the main gear/main shaft - all is good. All the pully's with the tooth belts are running freely without any friction. I have not taken the clutch assembly apart and is hoping that I don't have to.


Anyone with any ideas?


Jan

hi jan get a black marker put a line across the clamp and the bell housing try again if the mark don't line up then its still slipping and if its lineup most likely the clutch has problems maybe the liner is worn out.

How many hours do you have on it? Multi bladed head adding load?
If the clutch bell really hot when you land ( don't touch it! just putting a finger near will tell you if its really hot) if its really hot its slipping, all clutches slip a little, but it should not be that hot after a flight

Dave

How old is the PHT3 and what colour is the clutch bell housing - blue or silver.

Some time ago there was a problem with the shoulder of the bell housing cracking, so it didn't matter what you did to tighten it, it would still slip.
2, 4 or 5 blade head and what gearing is it set at - head speed ?
Serial number would also be helpful to see what batch it's from.

modtron
Oxford UK

Hi guys,

Thanks for your assistance. Here is what I think most of you are asking (sorry if I sound a bit vague, but I normally fly AMT turbines in jets - this is my only turbine heli and JC):

- the serial number is 878 I bought it new in 2008 and flown it only 22 times.
- total running time is 1h39m54s
- the clutch housing is blue
- I use a 2 blade head

I can hold the clutch housing with one hand and turn the rotor head while the pinion gear is turning.

Cheers,

Jan

the coller is loose put some locktite 608 compound on it and really tightening it up the same thing happen to our ph3 cobra.

Jan,

878 serial number is not particularly an old one and yes the collar does need to be done up mega tight,, but my guess is that it has a hair line crack in the centre boss.

Try contacting Roman at JetCat and see what he can do for you but it will most likely have to go back over to Germany to be sorted.

modtron
Oxford UK

Guy's,

I really don't want to go through the whole nine yards if I can at all help it.

Please confirm that the shaft from the pinion actually go through the blue clutch housing with the ali boss clamp. The clamp is obviously attached to the clutch housing - correct? If this is the case and I drill and tap a set screw into the clamp going slightly into the shaft, it should lock the housing to the shaft - right?

Thanks again for your help.

Jan

Hi guys,

Well since my previous post I have decided to undo the clamp bolt....and this was the result:

http://i253.photobucket.com/albums/h...2102671b89.jpg

...as you can see the clamp had obviously cracked and broken (I think this is what Modtron was suggesting). Well I guess I now would like to know what is the easiest way to take it out without (if at all possible) stripping it all out of my helicopter?

Cheers,

Jan

The only way is for the turbine to be removed - the official line from JetCat is that the engine position has to be reset and the belts adjusted while running under load - this is done by JetCat in a jig that let's them do this while it's running.
Some will tell you to just go and of it yourself.
It's your choice, but for warrenty cover, it would need to be done by them.

modtron
OxfordUK

hi jan,

y have te same problem also with a big vario bell and a big hughes, probably is the pht3 not strong enough for big helis , i have the problem on 2 helis ,

regards
wim