562 Auxiliary Power Unit (APU) (ATA 49) service difficulty reports for the Airbus A321 (all variants) — 1.5% of all reported difficulties.
Most reported components
- APU 259
- OIL SYSTEM 44
- O-RING 25
- COOLING FAN 15
- UNKNOWN 14
- PRESSURE SWITCH 13
- NONE 12
- EXCITER 11
- FCU 9
- FUEL CONTROL 8
- OIL COOLER 8
- IGNITER 8
- PACKING 7
- CONTROL VALVE 7
- PUMP 7
Report counts reflect fleet size and reporting activity, not relative safety or reliability. Source: FAA Service Difficulty Reporting System (public domain).