Incident: Porter DH8D near Toronto on Mar 1st 2010, hydraulics leak

09.03.2010 - 23:08

A Porter Airlines de Havilland Dash 8-400, registration C-GLQC performing flight PD-125 from Toronto City Center,ON (Canada) to Newark,NJ (USA) with 30 people on board, was climbing through 7000 feet, when a flight attendant reported a strange sound in the cabin, identifying the sound as a motor constantly operating. The flight crew assumed, it was the power transfer unit (PTU) and continued with the flight. After reached cruise level FL250 the pressure indication for hydraulics system #2 dropped to about 25% of its normal value. The crew contacted maintenance based to seek assistance in the evaluation of the fault, maintenance suggested the airplane should return to the City Center airport. The crew therefore turned around and approached Toronto s City Center Airport, lowered the gear and received three greens indicating the gear had reached its down and locked position. The crew noticed however, that the quantity indication for the #2 hydraulics system had dropped to zero, the according checklists indicated that the landing distance required with the hydraulics system inoperative had increased by factor 1.85. The crew therefore declared emergency and decided to divert to Toronto s Pearson Airport featuring longer runways, where the aircraft landed safely on runway 33R with emergency services on standby about 55 minutes after the pressure indication dropped to 25%. The crew steered the airplane to the apron using asymmetrical braking and asymmetric thrust. The Canadian TSB reported, that maintenance determined the Power Transfer Unit was draining hydraulics fluid from the PTU drive drain and thus depleted the #2 hydraulics system. The PTU and hydraulics filters were replaced, a functional test and a test flight performed and the airplane returned to service. Read the article at http://avherald.com/h?articleB86ab02 Modify your subscription at http://avherald.com/h?login