What is the maximum altitude for APU bleed operation?

The maximum altitude for APU (Auxiliary Power Unit) bleed operation is indeed 15,000 feet. This limitation is primarily in place due to the performance characteristics of the APU, which provides compressed air for cabin pressurization and engine starting.

Above 15,000 feet, the APU may not be able to provide sufficient airflow or pressure needed to operate systems effectively, potentially leading to inadequate air supply for the aircraft's environmental and pneumatic needs. This performance restriction ensures safe and effective operation of all systems relying on bleed air.

Understanding this limitation is crucial for flight planning and operations, as exceeding this altitude during APU bleed operation could compromise the aircraft’s systems and affect overall safety.