# SDR CALA2026011412962

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: January 11, 2026
- Submitted: January 14, 2026
- Operation: Air carrier
- Aircraft: [N39475](https://openairdocs.org/aircraft/N39475), registered now
- Make and model: Boeing 737924ER
- Aircraft serial: 37100
- Aircraft time: 38,957 hours, 14,152 cycles
- Engine: Cfmint CFM567B27E
- System (JASC): [7320 · Fuel Controlling System](https://openairdocs.org/jasc/7320)
- Part: Hmu
- Part number: 442653
- Part serial: BECW4444
- Condition: Faulted
- Location: Nr 1 Engine
- Part time: 57,977 hours, 21,581 cycles
- Stage of operation: TO
- How discovered: O
- Nature of condition: J
- Precautionary procedure: C
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/CALA2026011412962

## Discrepancy

N1 ON ENG 1 DIDNT SPOOL UP,  PERFORMED EEC BITE, TEST PASSED WITH NO FAULTS. ONLY FAULT SHOWING WAS 10 FLT CYCLES HPT ACC. PERFORMED ENG ACCELERATION CHECK IAW AMM 71-00-00-700-824-F00, FOUND NR 1 ENG SLOW TO SPOOL AS COMPARED TO NR 2 ENG.  TOOK BOTH THOTTLES TO 60% N1. NR 1 ENG WAS 3 SEC SLOWER TO REACH 60% THAN NR 2. AT THE SAME THROTTLE SETTING NR 2 ENGINE N1 IS 60.5%, N2 88.1%, EGT 522, FF 2.87. NR 1 ENG N1 61.1%, N2 88.5%, FF3.04, AND EGT 534. REMOVED PS3 AIR TUBE ON NR 1 ENG EEC & FOUND NO BLOCKAGE & REISTALLED IAW FIM 73-05, TASK 814, AMM 73-21-60-400-801-F00.  PERFORMED FIM 73-05 TASK 814. WAS ABLE TO DUPLICATE NR 1 ENGINE FROM IDLE TO N1 LIMIT TAKES 5-6 SECS MORE THAN NR 2 ENG. FROM IDLE TO 45% N1 TAKES THE LONGEST. PERFORMED ACCELERATION CHECK IAW AMM 71-00-00 TEST 8. TIME WAS 6.13 SECONDS VS 5.7 ON NR 2. FMV ON EEV ONLY PARAMETER WITH SMALL FLUCTUATIONS. REQUIRES HMU,  PERFORMED TASK 73-21-10-000-801-F00 UP TO INCLUDING STEP G (2) (I). REMOVED FUEL PUMP PACKAGE IAW  AMM 73-11-01-000-801.  INSTALLED NR 1 FUEL PUMP PACKAGE IAW AMM 73-11-01-400-801-F00 UP TO AND INCLUDING STEP 3.H(3)(M). AMM 73-11-01-400-801-F00 START FROM STEP 3.H.(4) UP TO AND INCLUDE STEP 3.H.(12)(P).

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.