Emery Worlwide Douglas DC-8-73 incident
Douglas DC-8-73 · Incident: airframe, component or system failure en route
From James M. Cox Dayton International Airport (DAY) to Seattle–Tacoma International Airport (SEA)
Event
- NTSB case
- SEA00IA108
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Incident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 0 · all aircraft and ground
- Ground fatalities
- 0
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- Airline
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
Douglas DC-8-73
- Aircraft type
- Douglas DC-8
- Category
- Airplane
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N831AL
- Operator
- Emery Worlwide
- Onboard fatalities
- Unknown
- Route
- From James M. Cox Dayton International Airport (DAY), Dayton, OHTo Seattle–Tacoma International Airport (SEA)
- Aircraft age
- Not recorded
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 121: Air Carrier
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- En route · cruise
- First occurrenceThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- Airframe, component or system failure
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- None
Cause areas
- Hydraulic system › Failure
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
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.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record SEA00IA108
- Event ID
- 20001212X21327
- Case number
- SEA00IA108
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: investigation status, damage. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: 19bed2507837af2e77f6c0347a5e547acd5ccec6866e0d40746a735b00d0efb4; retrieved 2026-09-18T16:34:06.414Z.