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| Date: | Saturday 17 June 2000 |
| Time: | 06:12 LT |
| Type: |  McDonnell Douglas DC-8-73 |
| Owner/operator: | Emery Worldwide |
| Registration: | N831AL |
| MSN: | 46149/538 |
| Year of manufacture: | 1970 |
| Total airframe hrs: | 52823 hours |
| Engine model: | CFMI CFM56 |
| Fatalities: | Fatalities: 0 / Occupants: 5 |
| Other fatalities: | 0 |
| Aircraft damage: | None |
| Category: | Serious incident |
| Location: | Seattle, WA -
 United States of America
|
| Phase: | En route |
| Nature: | Unknown |
| Departure airport: | Dayton, OH (KDAY) |
| (KSEA) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
The flight crew reported that while in cruise flight at flight level 310 (31,000 feet) they noted a loss of hydraulic fluid quantity in the aircraft's main hydraulic system reservoir. Shortly after powering the auxiliary rudder pump, the crew felt a '...chattering and feedback with the rudder pedals'. The crew also reported that the rudder momentarily deflected to the left. Post flight inspection of the aircraft's hydraulic system indicated that the auxiliary hydraulic pump was leaking fluid and that the hydraulic fluid quantity was at 'standpipe level'. Examination of the auxiliary hydraulic pump assembly revealed that the gasket located between the hydraulic pump mainframe and the AC electric drive motor, had failed. Further examination of the hydraulic pump subassembly revealed that the rate piston (part number 56909) was 'frozen' in the extended position. A frozen rate piston (in the extended position) could result in high internal case pressures capable of exceeding the manufactures specifications and the specifications of the gasket. Heavy scoring on the piston and the piston housing, with evidence of contamination were also noted.
Probable Cause: Auxiliary hydraulic pump leak resulting in a failure of the hydraulic system.
Accident investigation:
 |
|
Sources:
NTSB SEA00IA108
History of this aircraft
Other occurrences involving this aircraft
| 31 July 1997 | N874SJ | Southern Air Transport (SAT) | 0 | Copenhagen Katsrup Airport (CPH) |  |
non |
| Runway excursion | ||||||
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 03-May-2024 10:12 | ASN Update Bot | Added |
Corrections or additions? ... Edit this accident description
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