Safety Investigation Report 2018:1 Factual Information/1.6/1.6.8 Aircraft Systems/1
SAFETY INVESTIGATION REPORT MH370 (9M-MRO)
1) Air Conditioning and Pressurisation
The aircraft has two air conditioning systems divided into left pack and right pack. Engine bleed air provides the pneumatic source for air conditioning and pressurisation.
There are two electronic Controllers, each of which can provide both pack and zone control. Each Controller has two channels that alternate command cycle. Cockpit and cabin temperature selection is monitored, and the Air cycle machine and temperature control valves will be commanded to deliver temperature conditioned air to the various cabin zones.
Conditioned air is also used for electronic equipment cooling. This is supplied through a series of pneumatic valves with supply and exhaust fans. Exhaust air from the equipment cooling flow is routed to the forward cargo and used for forward cargo compartment heating.
Two cabin pressure Controllers regulate the aircraft pressurisation and command the pneumatic system. System operation is automatic and works in conjunction with the forward and aft outflow valves that are used for pressurisation. The outflow valves can also be manually operated from the cockpit by switches on the overhead panel.
Loss of cabin pressure will be indicated to the flight crew by a Cabin Altitude warning message on the Engine Indicating and Crew Alerting System (EICAS) display together with the associated aural warning.