# SDR CALA2026050415934

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: April 24, 2026
- Submitted: May 4, 2026
- Operation: Air carrier
- Aircraft: [N794UA](https://openairdocs.org/aircraft/N794UA), registered now
- Make and model: Boeing 777222
- Aircraft serial: 26953
- Aircraft time: 114,763 hours, 14,992 cycles
- System (JASC): [4900 · Airborne Auxiliary Power Unit (APU) System](https://openairdocs.org/jasc/4900)
- Part: Apu
- Part number: 38005501
- Part serial: 1176
- Condition: Faulted
- Location: Zone 100
- Part time: 40,189 hours, 27,814 cycles
- Stage of operation: TX
- How discovered: O
- Nature of condition: B
- Precautionary procedure: O
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/CALA2026050415934

## Discrepancy

ON TAXI OUT SMOKE STARTED TO COME INTO THE COCKPIT. AFTER THAT THE LT PACK FAILED AND RAN THE CHECKLISTS. SMOKE CLEARED ONCE LT PACK WAS SECURED.  FLIGHT CREW DEBRIEFED. FLIGHT CREW FOLLOWED SMOKE CHECKLIST. FLIGHT CREW FOUND LT PACK OFF LIGHT ILLUMINATED WHEN THEY WENT TO SHUT OFF LT PACK. APU NOT RUNNING. LT PACK STATUS MESSAGE ON STATUS PAGE. MMSG 21-24821 LATCHED ON EXISTING FAULTS TO INSPECT FOR OIL CONTAMINATION IN LT PACK, OZONE CONVERTER AND HEAT EXCHANGER INLET DUCT REMOVED AND REINSTALLED. NO SIGNS OF OIL CONTAMINATION. ACM INSPECTED FOR FREE MOVEMENT, CONFIRMED NOT SEIZED. APU DUCTING INSPECTED FOR CONTAMINATION. FOUND AND REMOVED EMPTY REMAINS OF DESI-PAK DESSICANT BAG FROM APU INLET SCREEN R/H PACK BAY HEAT EXCHANGER INLET DUCT REMOVED AND REINSTALLED. NIL SIGNS OF OIL CONTAMINATION. REF LP:8675503, PER TOMC REQ AND L PACK EVENT, LT PACK ACM REMOVED AND REPLACED. APU REPLACED ON L/P 8721020 AND JIC 27-0549-8-0004

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