Tail rotor upper shaft oil leak

[fraundo]

i flew my ship for the first time after a major overhaul was done on it other than 5 minutes when it was delivered post repair (it had a roll over after a full down auto that did not go well. I was not flying it I was watching my mechanic do a test flight after annual and he had a mishap, anyway that is a whole other story) and after a 30 minute flight there was some oil leaking out i believe of the area at the top of the tail rotor housing just below where it connects to main transmission. Threre is a shroud covering the termination point of the tail rotor shaft and that is where i think it was coming from. I called Harold since he did the rebuild and he said could be a bad seal at the top but he wants to take a look at it. I lost a lot of oil on that short flight. I topped the tail rotor fill plug off before the flight and after the flight the oil level was down below the shaft. Has anyone had a leak up at the top of that tail rotor shaft? It will be a while before Harold will make it to look at it and in the meantime i am interested to hear if anyone else has some insights.

I am not a mechanic, i am just a private pilot that thought it would be nice to own my own ship and the brantly was my choice. So i of course cannot work on this problem myself but i can hear what others think on the topic.

[9121u]

HI yes i have seen this before a simple check can be done ...what it could be and have seen before is the oil-light bearing in the tail rotor tube shaft the one that runs vertical.the bearing could be up side down there is a breather hole in in it so the system don't build up pressure in both shafts.and it could be your problem...easy way to check it is to pull off the clamp on the vertical shaft housing the holes should be lined up..there is 2 holes one for to hold the bearing and one for breather..very simple to check....or front seal o ring is bad on horizontal shaft up by trans.......hope this helps.....tom

[fraundo]

Thanks for the reply. I am glad to hear that it could be just a minor problem and easy to solve. I am hoping to be flying again soon.

Best regards,

Steve

[bryancobb]

YESS! 9121u is probably on the right track.

The short vertical shaft between the 2 T/R gearboxes has one Oillite bushing at about 75% of the way up.
That bushing has a 0.050" approx. hole drilled in the side of it. This hole must be clear and face rearward, and a hole must be drilled in the hollow aluminum tube that
the bushing resides in. This hole must LINE UP with the hole in the bushing.

This is the high-point air escape to avoid pressure building up in both the long and short hollow tubes. If the escape hole is present and located properly, a small amount of oil
will ALWAYS be splattered all over the vertical fin area, in flight. If your tail area is staying "nice-and-dry" then your hole in the bushing is installed wrong.

The front seal of the LONG drive shaft tube is the path of least resistance for oil to escape if the little air hole is not right.

[fraundo]

Hi I wanted to update on the oil leak I posted about a couple months ago. Harold passed through a few weeks ago and took a look at it and changed the seal up at the top of the tail rotor shaft. The old seal was out of round noticeably. I have flown it now for a couple of hours and no more leak. The vent hole on the vertical shaft was clear. Seems it may have just been a badly formed seal that got put in during the rebuild. Anyway it seems to be OK now and I am back flying.

Thanks again for the comments and advice to those who posted.

[9121u]

HI glad to here that is was a simple fix.and now you can enjoy flying it .ad at least you found a problem then stopped flying till it was repaired that's being a safe pilot...good job..well any way enjoy.......and be safe....tom