# SDR CALA2026082118803

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: August 20, 2026
- Submitted: August 21, 2026
- Operation: Air carrier
- Aircraft: [N13720](https://openairdocs.org/aircraft/N13720), registered now
- Make and model: Boeing 737724
- Aircraft serial: 28939
- Aircraft time: 83,083 hours, 29,549 cycles
- System (JASC): [2120 · Air Distribution System](https://openairdocs.org/jasc/2120)
- Part: Unknown
- Condition: Odor
- Location: Cabin
- Stage of operation: CL
- How discovered: O
- Nature of condition: B
- Precautionary procedure: A
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/CALA2026082118803

## Discrepancy

UNUSUAL ODOR & FUMES WHEN PACKS ARE ON THE ENGINE BLEED. ODOR & FUMES ARE NON EXISTENT WHEN PACKS ARE ON THE APU BLEED.  ODOR STARTED WHEN TRANSFERRING PACKS FROM APU TO THE ENGINE.  ODOR DISSAPATED WHEN TRANSFERRING BLEEDS FROM ENGINES BACK TO APU BLEED.   CONDITIONAL INSPECTION WAS COMPLIED WITH IAW TASK 05-51-26-800-801-C1, NO DEFECTS NOTED. PERFORMED HIGH POWER RUN WITH RECIRC FAN, BOTH BLEEDS, PACKS, APU BLEED, & WING AND ENGINE ANTI ICE, ALL CYCLED ON, NO STRANGE ODORS OR SMOKE. INSPECTED ACFT INSIDE & OUT. INSPECTED CARGO PITS, P91, FLT DECK AND NO DEFECTS NOTED.

---
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.