Service difficulty report · Shaft · Bell 206L

Difficulty date
June 28, 2001
Submitted
July 25, 2001
Operation
Air carrier
Make and model
Bell 206L
Aircraft time
12,551 hours
Engine
Allsn 250C20R2
Part
Shaft
Part number
206040222005
Condition
Corroded
Location
Freewheel Unit
Component
Freewheel · Bell · 206L
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

(CAN) DURING AN UNSCHEDULED MAINTENANCE REMOVAL OF THE UNIT IT WAS NOTED THAT THERE WAS EXCESSIVE PITTING CORROSION ON THE INNER SHAFT IN THE AREA WHERE THE FELT WIPER OF THE FORWARD SEAL RIDES. THE WIPER APPEARS TO ABSORB MOISTURE AND HOLDS IT IN CONTACT WITH THE SHAFT SURFACE RESULTING IN PITTING CORROSION. THE OLD STYLE SEAL (WHICH NO LONGER PROCURABLE) DID NOT HAVE A FELT WIPER AND THUS IT DID NOT CAUSE THIS PITTING CORROSION ON THE SHAFT. THE FORWARD SEAL (P/N 206-340-204-101) HAD 462.8 HOURS SINCE NEW.THE SHAFT WAS REPLACED DUE TO PITTING BEYOND LIMITS. WE HAVE NOW HAD FIVE SHAFTS REPLACED DUETO THE SAME PROBLEM WHICH SEEMS TO BE IN THE DEIGN OF THE SEAL.

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