Service difficulty report · Shaft · Skrsky S92A

Difficulty date
February 6, 2011
Submitted
September 9, 2011
Operation
Air carrier
Make and model
Skrsky S92A
Aircraft time
5,990 hours
Engine
Ge CT78A
Part
Shaft
Part number
9235115159041
Condition
Worn
Location
M/R Gearbox
Part time
3,076 hours
Stage of operation
IN
How discovered
V
Nature of condition
O
Precautionary procedure
K

As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.

What was found

ENGINEERS HAD GREAT DIFFICULTY IN REMOVING THE TTO SHAFT TO REPLACE A LEAKING SEAL. ONCE THE SHAFT WAS REMOVED SCORING AND FRETTING WEAR WAS EVIDENT. ENGINEERING WAS CONTACTED. THEY REQUESTED MEASUREMENTS BE TAKEN ACROSS 2 PINS PLACED IN THE SPLINES 180 DEGREES APART (IN SEVERAL PLACES). THIS WAS DONE AND THE MEASUREMENTS PROVIDED TO MFG. AFTER THEIR REVIEW OF THE MEASUREMENTS THEY ADVISED REPLACEMENT OF THE MAIN MODULE BECAUSE THE CIRCULAR TOOTH THICKNESS WAS NO LONGER WITHIN ACCEPTABLE LIMITS. MGB MODULE TO BE RETURNED FOR INVESTAGATION INTO WHAT CAUSED THE ACCELERATED WEAR.