Service difficulty report · Modulating Valve · Boeing 737890

Difficulty date
October 4, 2008
Submitted
October 10, 2008
Operation
Air carrier
Aircraft
N557AS
Make and model
Boeing 737890
Aircraft serial
35176
Aircraft time
8,954 hours, 2,653 cycles
Part
Modulating Valve
Part number
3989083
Part serial
8654
Condition
Failed
Location
Rt Pack
Part time
8,954 hours, 2,653 cycles
Stage of operation
CR
How discovered
O
Nature of condition
M
Precautionary procedure
K

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

What was found

IN FLIGHT RIGHT PACK TEMP EXCEEDED 80 CELSIUS WITH TEMP CONTROLLERS IN FULL COLD SUPPLY DUCT TEMP 40 CELSIUS CAB TEMP 32 CELSIUS. WORSE WITH TRIM AIR OFF. TURNED PACK OFF AND TEMPS DECREASED. PERFORMED BITE TEST OF BOTH ZONE TEMP CONTROLLERS. FOUND RT TEMP CONTROL VALVE FAILED. SWAP RT TEMP CONTROL VALVE WITH AFT TRIM AIR VALVE. PERFORMED ZONE TEMP CONTROL BITE AND CHECKS GOOD. SYS OPS CHECKED NORMAL. REF FIM 21 61 00 AMM 21 51 10 AND AMM 21 61 21. C N 1003011 VERIFIED RT OPS CHECKED OK. PERFORMED BITE CHECK ON BOTH TEMP CONTROLLERS RT AFT CABIN ZONE TRIM AIR MOD VALVE FAULT LIGHT ILLUMINATED. REMOVED AND REPLACED RT AFT CABIN ZONE TRIM AIR MOD VALVE, OPS LEAK CHECK GOOD. GROUND VERIFICATION SUCCESSFUL.