Investigation report released on the May 2005 serious BAe ATP incident near Ronaldsway, UK: Shortly after takeoff, a seal associated with the retraction line for the hydraulically operated integral airstairs at the front left cabin door, failed. This allowed hydraulic fluid to escape in the form of a fine mist, depleting the contents of the main hydraulic system. This misting was perceived by the cabin crew as smoke, and they informed the flight crew accordingly. In flight, this line is normally de-pressurised but, owing to a jammed airstairs UP selection switch and a stuck door safety microswitch, it had remained pressurised.
The intensity of the misting in the forward section of the cabin led the cabin crew to reposition the passengers towards the rear of the cabin. As a result, the aircraft’s centre of gravity (CG) position moved beyond the operator’s specified aft limit.
An emergency was declared to ATC and the aircraft returned to Ronaldsway. During the approach, the EGPWS system alerted the crew to an incorrect flap setting for landing.
After landing, the aircraft was taxied clear of the runway but difficulties encountered with the nosewheel steering system forced the commander to stop the aircraft short of the terminal buildings. (AAIB)