AAIB investigation to Boeing 737-36Q, G-GDFT
Smoke in cabin/cockpit and emergency evacuation, East Midlands Airport, 03 September 2014.
The aircraft landed at East Midlands Airport following an electrical failure in flight, which the crew diagnosed as a failure of the battery busbar . As the aircraft taxied towards its parking stand, an acrid smoke haze appeared within the cabin and flight deck and an emergency evacuation was carried out. Although the aircraft was successfully evacuated, cabin communication difficulties were encountered, due to the failure of the PA system and a fault with a loud hailer unit.
The battery bus failure was caused by one or more loose R1 relay terminals, leading to a break in electrical continuity. The acrid smoke in the cabin and cockpit was a direct result of the relay failure. The loss of the air cycle machine (ACM) cooling fans caused dust and oil residue to burn off the hot metal duct surfaces in the air conditioning system and the resulting fumes entered the cabin, prompting the evacuation.