Service difficulty report · Valve · Boeing 767322

Difficulty date
February 20, 2011
Submitted
March 17, 2011
Operation
Air carrier
Aircraft
N657UA
Make and model
Boeing 767322
Aircraft serial
27112
Aircraft time
78,363 hours, 12,591 cycles
Engine
Pwa PW4060
Part
Valve
Part number
3790037108
Part serial
58
Condition
Faulted
Location
Nlg Steering
Stage of operation
IN
How discovered
9
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

NOSE STEERING CHECK. DUPLICATED AND ISOLATED STICKING STEERING TO METERING VALVE. REPLACED IAW AMM. STICKING ISSUE RESOLVED, BUT NEW VALFE FAILED OPS CK. INTERMITTENTLY HARD TO MAKE RT TURNS. SUSPECT BAD VLV FROM STOCK. REPLACED METERING VALVE AGAIN, NO HELP. STEERING IS SLOW IN BOTH DIRECTIONS FROM FULL TILLER TURN BACK TO NEUTRAL. CONFIRMED 3000 PSI TO METERING VALVE USING A PRESS GAUGE AT VALVE. RE-INSTALLED ORIGINAL VALVE. STEERING FORCE AND RETURN TO NEUTRAL. NOW NORMAL WITH THE EXCEPTION ORIGINAL PROBLEM, STEERING STICKING. SECOND VALVE ALSO BAD FROM STOCK. NLG STEERING SUMMING MECHANISM COVER REMOVED FOR ACCESS TO METERING VALVE REPLACED. PLACED IN COCKPIT. RE-INSTALLED COVER.