Factual Information 2015:Appendix 1.6E/1.6E.19
This page contains an extract from MH370/01/15 Factual Information which accompanied the (first) Interim Statement released by The Malaysian ICAO Annex 13 Safety Investigation Team for MH370 on 8th March 2015.
1.6E.19 Auxiliary Power Unit (APU)
The aircraft is fitted with an APU (Model: GTCP 331-500) manufactured by Allied Signal. The Allied Signal GTCP 331-500 gas turbine APU is a two stage centrifugal flow compressor, a reverse flow annular combustion chamber and a three stage axial flow turbine. It supplies the auxiliary power system for the aircraft pneumatic and electrical power. This permits independent operations from the ground external power sources or the main engines.
The APU generator supplies 120 KVA electrical power at any altitude. Pneumatic pressure is available up to an altitude of 22,000 feet (6,700 m).
The ELMS contains the APU autostart logic and sends signal to the APU Controller (APUC).
The APU Controller serves to control the APU functions for:
- Starting and ignition
- Fuel metering
- Surge control
- Inlet guide vane (IGV) control
- Data storage
- Protective shutdown
- BITE/Fault reporting
- APU indication
The APU is designed to automatically start when certain logic conditions are met when the aircraft is in the air or electrical power removed from left and right transfer buses from respective No. 1 and No. 2 engine generators.
Source: Malaysian ICAO Annex 13 Safety Investigation Team for MH370, 8 March 2015, Factual Information MH370/01/15
The Factual Information was updated in 2018 by the Safety Investigation Report MH370/01/2018 which added new content but did not include all of the previous data.