Service difficulty report · Servo · Bell 212

Difficulty date
December 14, 2011
Submitted
September 14, 2015
Operation
General aviation
Make and model
Bell 212
Engine
Pwa PT6T3
Part
Servo
Part number
212076005101
Condition
Defective
Location
Flight Control
Stage of operation
UK
How discovered
O
Nature of condition
F
Precautionary procedure
K

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

What was found

(CAN) SERVO RECEIVED ZERO TIME SINCE OVERHAUL. CUSTOMER REPORTED LOWER CYLINDER ASSEMBLY LOCKS HYD WILL NOT EXTEND. SUSPECT IMPROPER BYPASS SERVO TIMING. SERVO FUNCTIONALLY TESTED PRIOR TO DISASSEMBLY. THE SERVO LOWER PISTON MOVED TO THE EXTEND POSITION BUT WOULD NOT RETRACT. UPPER PISTON DID NOT MOVE. INPUT LEVER FORCE WAS VERY HIGH AT 6 LBS, SHOULD NOT EXCEED 1.5 LBS. SERVO VLVS & BYPASS VLVS WERE WORN & OUT OF ADJUSTMENT. VLVS WERE RUNNING BETWEEN 0.003 & 0.004 ON EITHER SIDE OF NULL, SHOULD BE 0.010 TO 0.013. PISTON WAS FOUND TO BE NOT HONED, INPUT BUSHING WERE WORN OVERSIZE & 1 SPLIT BUSHING WAS CRACKED.

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