# NTSB SEA00IA108: Douglas DC-8-73, N831AL, Seattle, WA, June 17, 2000 - Type: NTSB incident investigation - Classification: Incident · No injuries · Incident investigation · Final report - Date: June 17, 2000, 06:12 local (13:12 UTC) - Place: Seattle, WA - Coordinates: 47.440269, -122.279762 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=47.4403&lon=-122.2798&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 5 uninjured - Status: Completed, report May 18, 2001 - Report: Approved by Office Director - NTSB case key (mKey): 49467 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA00IA108 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/49467/pdf - Page: https://openairdocs.org/ntsb/SEA00IA108 ## Probable cause Auxiliary hydraulic pump leak resulting in a failure of the hydraulic system. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, cruise - normal - hydraulic system,auxiliary pump - leak (contributing factor) - hydraulic system - failure (cause) ## Analysis 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. ## Factual narrative On June 17, 2000, about 0612 Pacific daylight time, a Douglas DC-8-73, N831AL, registered to Wilmington Trust Company, and operated by Emery Worldwide Airlines (EWA) as a 14 CFR 121 supplemental cargo flight, declared an emergency subsequent to a failure of the aircraft's systems. Visual meteorological conditions prevailed and an instrument flight plan was filed. The aircraft landed at it's planned destination, Seattle-Tacoma International Airport, Seattle, Washington, without further incident. There were no injuries, no aircraft damage and no report of fire. The flight originated from Dayton, Ohio, approximately 3 1/2 hours prior to the incident. 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. After de-powering the system, the flight crew declared an emergency with Seattle Air Route Traffic Control System (ARTCC) and landed without further incident. Maintenance personnel from EWA reported that a post flight inspection of the aircraft's hydraulic system indicated that the auxiliary hydraulic pump was leaking fluid. They also reported that the hydraulic fluid quantity was at "standpipe level". On June 30, 2000, representatives from Aero-Craft Hydraulics, Inc, and the Federal Aviation Administration, inspected the auxiliary hydraulic pump assembly. Examination of the assembly revealed that a gasket (part number MS9134-01), 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. Heavy scoring on the piston and the piston housing, with evidence of contamination were also noted. Representatives from Aero-Craft Hydraulics reported that 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 (Report Attached). ## Aircraft - Registration: [N831AL](https://openairdocs.org/deregistered/N831AL-2007-10-16), registration cancelled 2007-10-16, S/N 46149, built 1970 (OpenAirDocs) - Reported make and model: Douglas DC-8-73 - Registry model: [Douglas DC-8-73](https://openairdocs.org/model/douglas-dc-8-73) (registry code 302199C) (OpenAirDocs) - Registry engine: [Pratt & Whitney JT3D-3&3B](https://openairdocs.org/engine/pratt-whitney-jt3d-3-3b) (registry code 52039, turbo-fan) (OpenAirDocs) - Category: Airplane - Serial number: 46149 - Airframe hours: 52823 - Engines: GE CFM 56 22000 lbs thrust turbo fan - Damage: No damage - Flight: Part 121 - Operator: Emery Worlwide - Registered owner: Wilmington Trust Company - Airworthiness certificate: Standard, Transport - Last inspection: Continuous airworthiness, June 4, 2000, 60 hours before - Departed: DAY, DAYTON, OH - Destination: SEA - Flight plan: IFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 53; commercial, flight engineer, airline transport; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, valid medical--w/ waivers/lim; seat: left ## Weather - Conditions: Visual (VMC), Dawn - Visibility: 10 statute miles - Lowest ceiling: 20,000 ft broken - Temperature: 54 °F, dew point 48 °F - Altimeter: 30.00 inHg - Observed at: SEA ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Incident 20000617034709I](https://openairdocs.org/incident/20000617034709I), Jun 17, 2000: Doug DC873, Seattle, WA. (-23)Emery FT026 ay-sea enroute lost hydraulic quanity to standpipe. Required 10 degrees right rudder to center trim ball. Turning on rudder pump caused… From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.