377 Air Conditioning (ATA 21) service difficulty reports for the Boeing 747 — 1.4% of all reported difficulties.
Most reported components
- UNKNOWN 84
- FAN 69
- VALVE 15
- ACM 14
- DUCT 13
- COOLING FAN 13
- CONTROLLER 11
- ODOR 11
- A/C PACK 10
- OUTFLOW VALVE 10
- COALESCER BAG 9
- SENSOR 8
- ACTUATOR 6
- WARNING MESSAGE 6
- HUMIDIFIER 5
Report counts reflect fleet size and reporting activity, not relative safety or reliability. Source: FAA Service Difficulty Reporting System (public domain).