SDR ASAA2020021063127

Service difficulty report · Valve · Boeing 737990ER

Difficulty date: February 6, 2020
Submitted: February 19, 2020
Operation: Air carrier
Aircraft: N494AS
Make and model: Boeing 737990ER
Aircraft serial: 41729
Aircraft time: 15,959 hours, 5,018 cycles
System (JASC): 3610 · Pneumatic Distribution System
Part: Valve
Part number: 632921461
Part serial: 2445
Condition: Failed
Location: Precooler
Part time: 9,100 hours, 2,761 cycles
Stage of operation: CL
How discovered: O
Nature of condition: J
Precautionary procedure: O

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

What was found

AIR CONDITIONING DUCT PRESSURE SPLIT GREATER THAN 20 PSI IN CLIMB AND INITIAL CRUISE, LEFT DUCT 20 PSI VS RIGHT DUCT 43 PSI, AFTER 20 MINUTES IN CRUISE FLIGHT LEFT DUCT 23 PSI & RIGHT DUCT 40 PSI. GROUNDED - YES. ACCOMPLISHED BLEED AIR SYST HEALTH CK REF B737-900 AMM 36-11-00. PCV FAILED. REMOVED AND REPLACED #1 ENG PRECOOLER CONTROL VALVE PER AMM 36-12-02. LEAK CHECKED AND OPS CHECKED GOOD. PERFORMED ENGINE RUN TEST AMM 36-11-00-710-801. SYSTEM OPS CKS GOOD.