It is also fitted with auxiliary power unit, which powers all systems, when the main engine is turned off.

它还配备了辅助动力装置，它的权力的所有系统，当主发动机是关闭的。

BLEED VALVE, A valve in the pneumatic system for air supply from the engine or auxiliary power unit to the pneumatic manifold.

引气活门，气源系统内， 使来自发动机或辅助动力装置的空气进人气源支管的活门。