Spectra G sealed tail gear box.

[malc1]

I had a minor mishap yesterday after the tail linkage came off in flight and I managed to just touch the tail blades in the ground during the landing.

I have got away with it quite lightly but have stripped the Inner drive gear and slightly damaged the tail blades.
The tail boom ended up very slightly rotated.

I'm not sure whether I have done anything to the tail output shaft so was going to possibly replace it as a precaution.

I have also noticed a bit a bit of play in the gear box as well that has probably been there for some time though.

Is this gear box assembly fully serviceable or does it have to be sent away?

Also tried to get the tail hub off the output shaft with not a lot of luck.
Removed the two screws expecting it to just come off but it just will not move.

Any ideas with this?

As I'm in the UK I'm just trying to work out what spare parts I need to get the helicopter back in the air before doing an international order.

[rbort]

First of all just spin the main rotor and stare down the tail output shaft head on (from the left side eyes level with its tip). If you see no movement at all then its most likely fine. Of course if its bent you're going to see something moving from that angle.

2nd if you do a tail strike (I've done several) its always possible to strip the plastic crown gear but the tail rotor gears always survived for me throughout the years. The plastic lets go first, they are metal. What wears them out is vibrations and wear from running, not from a tail strike.

3rd if you need to take the hub off then just heat it with a heat gun and while holding the main rotor still twist it off with a rag. It should come off alot easier this way.

4th a bit of play in the metal gears is normal. If you want you can disassemble it to check the gears and re-grease and put back together. There is a sequence of disassembly to make things easy, if you don't know how let me know and I'll tell you.

-=>Raja.

[malc1]

Thanks Raja

I was going to completely strip the gear box down to take a look but have got so far and really can't get the hub off.
I've tried heat and twisting and lightly tapping but still end up with the thing still in exactally the same place.

The play when you rock the tail assemble back and forth is as you say more likely to be just wear so maybe to save destroying things while trying to dissassemble I may leave it alone for now.
The pitch slider is still very smooth on the shaft - I would have thought this would bind somewhere along it's length if I had bent it,so maybe it's OK.

No much of an incident really but very lucky.
I had the tail ball link un clip itself from the ball at the fuselage end and was lucky as I was only about 15 feet up.Not much head speed but tail blades just touch the ground at enough of an angle to just twist the boom out of alignment.Heard the gear go at this point.

Checking the ball link and it has gone so loose.I had changed others that had gone 'sloppy' only last week but must have missed this one.

Anyway so it looks like maybe just the gear and a pair of those Telfon o rings to get it back in the air.

I wouldn't think that there are any spares over here in the UK so will just have to price up getting the parts from either the US or Australia.

Its the $26.00 standard shipping fee and possible customs duties that are the pain in the butt here.

[malc1]

That's the inner gear sorted.

Unusually the UK dealer just happened to have some in stock - so I bought two.

[rbort]

Another way to pull it off is to use some puller and push on the shaft while trying to pull on the arms after taking the blade grips off.

I would not take it off if the shaft is not bent as you might damage something in the process. If the shaft is bent then you could just hold it with vice grips and twist the hub off with a pipe wrench and some leverage. There are ways, good and bad ways to do things, if parts are damaged and you're just trying to take things apart you don't have to worry much about the ways you take them apart if you see what I mean as you're going to throw away the shaft anyways afterwards.

Let me know how you make out.

-=>Raja.

[malc1]

Yeah I thought the same about getting this hub off - if the shaft has to be replaced it doesn't matter too much about damaging it further.
I even thought yesterday about getting the Dremel out and just cutting the shaft in half to get it all to pieces.

Thinking now of just regreasing the bearings in the tail grips and the tail case and getting it all back together.
If I'm getting tail problems/vibrations that were not there on Saturday before the mishap then I'll look at it further and sort out some new parts.

[rbort]

Please just look at the shaft head on and spin the head. If its bent you're going to see it. Look at the shaft part that you see on the other side of the hub head on and spin the rotor. If its not bent the outer circle of the shaft edges will look like its running true.

Simple, that's how I check mine after any issues, and if it looks good then I'm good.

Also note that in the event of disassembly, its possible to get the shaft out of the tail rotor case with the hub still on it, going out the same direction as the shaft sticks out of the tail case.

-=>Raja.

[malc1]

OK Raja I'll have a look at this later.

I've reassembled the tail section anyway and just need to get it refitted to check this out.

Can't see how the tail shaft can be removed without getting the hub off though.
There's that large circlip on the open end and surely it needs come out this end.

Unless I'm missing something.

Edit : slide the shaft out and remove the bearings,circlip and gear from it and then pull out through the smaller hole?

[rbort]

Loosen the 2 set screws in the side of the case and pull the input shaft out.

Remove the m3 bolt that holds the rear arm that carries the pitch slider.

Behind that is a hole where you can put an allen screw driver in and loosen the two set screws in the tail crown gear on the shaft each 1 1/2 turns exactly. Fish around to find one and then the next will be 90 degrees later.

Once the set screws are loose, you can push the shaft in and put a bit and the bearing can move away from the circlip to make it easier to remove.

Remove the circlip, then push the shaft out the back in and remove the bearing and the clip behind the bearing.

Then you can pull the shaft out the other way and the crown gear and spacer should come out or fall out the back end.

Hope this helps.

-=>Raja.

[malc1]

Invaluable information,thanks Raja.