Service difficulty report · Control Valve · Boeing 737990ER

Difficulty date
May 7, 2016
Submitted
May 9, 2016
Operation
Air carrier
Aircraft
N407AS
Make and model
Boeing 737990ER
Aircraft serial
41731
Aircraft time
13,920 hours, 4,451 cycles
Part
Control Valve
Part number
3989084
Part serial
18518
Condition
Failed
Location
A/C Bay
Part time
13,918 hours, 4,450 cycles
Stage of operation
NR
How discovered
9
Nature of condition
O
Precautionary procedure
O

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

What was found

F/A REPORTED CABIN WAS VERY HOT. FWD CAB SUPPLY DUCT TEMP READ 60 DEGREE C AND WOULD NOT COOL DOWN WITH TEMP SELECTED TO MAXIMUM COOL. QRH RAN, TRIM AIR TURNED OFF AND TEMPERATURE COOLED DOWN. TRIM LIGHT CAME ON AFTER QRH. ACFT GROUNDED. BITE TEST OF RT CONTROLLER SHOWS TRIM VALVE ZONE FAULT. WOULD NOT RESET. REPLACED V144 TRIM VALVE IAW AMM 21-61-21-000-801 AND AMM 21-61-21-400-801. OPS GOOD IAW AMM SUBTASK 21-61-212-740-001. BITE PASSED AND DUCT SUPPLY TEMP WENT WAY DOWN. ALSO FOUND ALL TEMP SENSOR FILTERS DIRTY. THEY WERE ALL CHANGED ON THE A-5 CHECK. GROUND VERIFICATION GOOD IAW AMM TASK 21-61-00-700-807-002. LEAK CHECK GOOD.