NTSB Identification: DEN04IA060.
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Scheduled 14 CFR operation of Horizon Air (D.B.A. operation of Horizon Air)
Incident occurred Sunday, April 11, 2004 in Denver, CO
Probable Cause Approval Date: 12/03/2004
Aircraft: Canadair CL-600-2C10, registration: N609QX
Injuries: 60 Uninjured.

NTSB investigators used data provided by various sources and may not have traveled in support of this investigation to prepare this aircraft incident report.

The captain reported that while in cruise flight at flight level 330, the crew received a master caution light and a hydraulic system 1 low pressure along with warning lights for the outboard ground spoilers, outboard spoilerons, and the outboard spoilers. The hydraulic fluid quantity and fluid temperature readings were good, but the system pressure was dropping. The crew ran the emergency checklist and continued their flight to Denver, using the backup (1B) system. On final approach and landing, the captain reported that they lost number 1 system pressure and quantity. The crew shut off the 1B system and continued to land. After landing, the crew shut down the number one engine and taxied to the gate. A post-incident examination of the airplane's number 1 hydraulic system showed that the hydraulic pump had come apart internally and seized. Metal fragments were found in the hydraulic filters and lines. Further examination of the hydraulic pump showed that several piston shoes in the pump's hanger and piston subassembly had come apart. The resulting metal fragments subsequently caused damage to the hold-down plate, the hanger, and other internal components of the pump, resulting in its seizure.

The National Transportation Safety Board determines the probable cause(s) of this incident to be:

The total failure of the airplane's number 1 system hydraulic pump.

Full narrative available

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