SDR CALA2025111711228

Service difficulty report · Check Valve · Boeing 737924ER

Difficulty date: November 16, 2025
Submitted: November 17, 2025
Operation: Air carrier
Aircraft: N37456
Make and model: Boeing 737924ER
Aircraft serial: 37205
Aircraft time: 41,683 hours, 15,338 cycles
System (JASC): 3500 · Oxygen System
Part: Check Valve
Condition: Faulted
Location: Zone 100
Stage of operation: IN
How discovered: V
Nature of condition: G
Precautionary procedure: K

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

What was found

LEAK CHECK OF NITROGEN GENERATION SYSTEM, RESIDUAL FUEL & FUEL ODOR AT BOTH DRAIN PORTS, REQUIRES PRIMARY AND SECONDARY BACKFLOW PREVENTION CHECK VALVES TO BE CHANGED IAW AMM 47-21-04. R & R SECONDARY BACK FLOW PREVENTER PER AMM TASK 47-21-04. PERFORMED OPS & LEAK CHECKS. OPS CHKD GOOD. AND NO LEAKS NOTES IAW AMM TASK 47-00-00-790-802. PERFORMED REQUIRED ALI INSPECTIONS AND VERIFIED NO LEAKS AND COND OF NEADS LINE OND NO2 SYS AS REQUIRED. REF AMM 47-00-00-790-802.