Bell 407 Transmission Problems

[NY HELICOPPER]

We recently had a bad bearing in a fairly new Bell 407 transmission (1300 hours-ish) and just got another chip light. Sadly the detector was full of some fairly large metal particles so the transmission is off to the shop again (at 1520 hours).

Is anyone else having problems with 407 transmissions with fairly low time?

This same aircraft had a mast overtorqued when almost new by the Bell service center rep doing warranty work. Any possibility this is related to that incident?

Your thoughts and any recent experiences with similar problems are appreciated.

[blackhand]

Hi NY Helicopter
Shouldn't imagine that over torquing the Mast Nut would cause bearing or gear damage to transmission.

Currently working with a fleet of 6 x 407 and no problem with transmission chips.

Seen case with 206 transmission that had a worn mast bearing that took overhaul shop two tries to find.
BTW which chip detector had the debris on it? Upper or lower?

Cheers
BH

[Saint Jack]

With regard to suspect 206 mast bearings, a little trick I learned many years ago was to run the helicopter at idle and while the mechanic was in the rear cabin with his ear close to the roof trim, get the pilot to raise the collective slightly, enough to create an upward force on the mast bearing, and then listen for a slight 'rumble' sound indicating a 'chipped' bearing. Running at 100% produces too much noise. I'd be interested to hear if this works with a 407.

[spinwing]

Mmmm ...

Saint Jack ....

Now THAT is a clever way to find the fault .... well done :ok:


:D

PS I done similar but with one of those acustic probes held against the Xmsn case but as you say the ambient noise often beats you ....

Ahhh the days before electronic vibration analysis .... do I miss them ...... NO! ;)

[NY HELICOPPER]

It was the lower chip detector both times.

[rotornut]

Niagara Helicopters has a fleet of 407s - 7 I believe. Maybe they can advise you: Niagara Helicopters Ltd - Contact Us (http://www.niagarahelicopters.com/contact/)