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Ground staff fled as brake failed in Aer Arann plane

AIRPORT staff were forced to run clear when an Aer Arann plane did not stop after a parking brake failed.

None of the ground crew or the 37 passengers and crew on board were hurt. But the twin-engine ATR 72 plane suffered significant damage to propeller blades while stand infrastructure was also damaged.

The incident happened at Manchester Airport after a flight from Galway on October 21, 2009, a just-published UK Air Accident Investigation Branch report said.

After an uneventful flight, the aircraft came to a halt on stand and the crew applied the parking brake before feathering both propellers.

Ground crew approached the plane while anti-collision lights were flashing and attached an electrical power cable.

"Although their procedures required them to insert chocks (wedges under the wheels to prevent accidental movement) they did not do so," the report said.

"The aircraft then started moving slowly forwards, so the ground crew ran clear. Both pilots attempted to stop by applying the toe brakes, without success, after which the commander exercised the parking/emergency brake lever."

The commander, seeing the aircraft was not under control, gave an alert call to the cabin crew and instructed the co-pilot to shut the engines down.

The co-pilot switched off the engines and radioed air traffic control to say the aircraft was in difficulties and asked for the attendance of the fire and rescue service. The plane rolled forward until the No 2 engine propeller struck a stand guidance mirror.

Both the mirror and propeller were damaged.





Thrust

Later, both pilots recalled considering using reverse thrust to attempt to halt the plane's movement and back away from the stand.

"However, they recognised that before reverse thrust was achieved, the propellers would produce forward thrust for a short period; they considered that this strategy had the potential to make the situation worse," the report said.

The investigation determined that a failure of a hydraulic fuse in the parking/emergency brake had led to a loss of the brake accumulator hydraulic pressure.

As a result of the accident, discussions about ground handling involving the Civil Aviation Authority, Health and Safety Executive and airline representatives had been instigated, but the report did not make any safety recommendations about ground handling.

mlavery@herald.ie