High RPM sound from the tail

[Hizlimax]

Hi everyone,

Had a hard landing/crash a few weeks ago. Thought I was going to Idleup1 from Idleup2, but realized I was already on IU1 so the power cut...I was shocked so couldn't auto it correctly. Replaced all the blades, main shaft, main gear, tail rotor hub and landing gear. Main shaft and tail rotor hub were bent. It is back to flying perfectly, but I hear a "trrrrrrrr" sound that comes and goes when I'm at full RPM set to 2350. Can you guys check out this link and help me find the cause of it? Thanks.

E5 High RPM Sound

[James F]

Sounds like either gears or a bearing running very rough.  I have had torque tube bearings howl when they were on there way out.

[Mike Spano]

Did you replace the tail output shaft and the hub?

[Jeff_Barrett]

I agree, sounds like something in the tail maybe.

Check that the grip arms aren't bent where the ball links are (make sure they track true) and check the output shaft as already suggested.

It's hard to see on video, can you visibly detect any vibrations in the tail fin or tail boom supports?

[Hizlimax]

I agree, sounds like something in the tail maybe.

Check that the grip arms aren't bent where the ball links are (make sure they track true) and check the output shaft as already suggested.

It's hard to see on video, can you visibly detect any vibrations in the tail fin or tail boom supports?

I just replaced the tail hub Part Number 615-323 and not the output shaft. It looked fine, but since the hub was bent it is possible that the output shaft is also slightly bent. I will remove and roll it on a glass table. I will also do a full throttle bladeless test to check for vibes. Thanks a lot guys for the comments. I will report once I check those.

[Hizlimax]

Disassembled the tail and the output shaft was fine. Realized the torque tube was doing circles inside the boom when its turning. Turns out both the torque tube and the tail boom are bent. Thanks for the help everyone.

[Mike Spano]

glad  you got this sorted. somehow I missed that anyone had responded to the thread......glad to know what the sound was though, I have a buddy who's E7 sounds like this, but he cant figure it out...passing this along to him now....

[Hizlimax]

Glad to be of help to him.

[Jeff_Barrett]

Glad you got it solved!