# NTSB SEA02IA044: Bombardier DHC-8-401, Boise, ID, March 2, 2002

- Type: NTSB incident investigation
- Date: March 2, 2002, 01:40 UTC, 18:40 local (the day before locally)
- Place: Boise, ID
- Location: 43.6135° N, 116.2035° W: Placed by OpenAirDocs: center of Boise, ID, within about 6 miles (OpenAirDocs)
- Highest injury: No injuries
- Injuries: 73 uninjured
- Status: Completed
- Report: Approved by Office Director, June 3, 2002
- Parties: Boise FSDO
- NTSB case key (mKey): 54292
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA02IA044
- NTSB report (PDF): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/54292/pdf
- NTSB docket: https://data.ntsb.gov/Docket?ProjectID=54292
- Page: https://openairdocs.org/ntsb/SEA02IA044

## Probable cause

The partial failure of one of the number two hydraulic system elevator hydraulic lines, leading to the loss of fluid and pressure in that system during cruise flight. This loss resulted in reliance upon the sole remaining activation system (number one hydraulic) to operate the rudder.

## Analysis

During en route cruise, there was a failure of a number two system elevator hydraulic line. This resulted in a loss of hydraulic fluid and loss of pressurization in the number two system. The loss of this system resulted in the rudder being dependent upon the sole remaining activation system (hydraulic system number one) for its operation. After the landing gear was lowered manually, the aircraft landed without further incident, but because the loss of the number two system rendered the nose wheel steering inoperative, the aircraft had to be towed from the runway. The reason for the failure of the hydraulic line could not be positively determined.

## Factual narrative

On March 1, 2002, approximately 1840 mountain standard time, a Horizon Airlines Bombardier DHC-8-401, N410QX, experienced a failure of the number two hydraulic system during en route cruise to Boise, Idaho. The airline transport pilot, his first officer, the two flight attendants, and the 69 passengers were not injured, and the aircraft did not sustain any damage. The 14 CFR Part 121 scheduled passenger flight, which departed Seattle-Tacoma International Airport, Seattle, Washington, about two hours earlier, was being operated in visual meteorological conditions. The flight, which was on an IFR flight plan, eventually landed at its destination around 1900. There was no emergency evacuation.

According to the flight crew, during en route cruise, they noticed the number two hydraulic system quantity beginning to decrease. As they began to run the appropriate checklist, they noticed the illumination of several hydraulic system caution lights. Eventually, the number two system lost pressurization, and the rudder became dependent upon the sole remaining system (hydraulic system number one) for its movement. After the landing gear was extended manually, the aircraft landed without further incident, but it had to be towed from the runway, as the failure of the number two system rendered the nose wheel steering inoperable.

It was later discovered that the number two system hydraulic line to the elevator had failed, leading to a loss of pressure in the number two system. The reason for the failure could not be positively determined.

## Sequence of events

- Airframe/component/system failure/malfunction, cruise - normal
  - hydraulic system,line - failure,partial (cause)
  - fluid,hydraulic - starvation (cause)
  - hydraulic system - inoperative (cause)

## Aircraft

- Registration: N410QX, a cancelled registration (https://openairdocs.org/deregistered/N410QX-2019-12-23) (OpenAirDocs)
- Reported make and model: Bombardier DHC-8-401
- Registry model: Bombardier DHC-8-402 (registry code 1390042, https://openairdocs.org/model/bombardier-dhc-8-402) (OpenAirDocs)
- Registry engine: Pratt & Whitney Canada PW150A (registry code 52167, https://openairdocs.org/engine/pratt-whitney-canada-pw150a) (OpenAirDocs)
- Category: Airplane
- Serial number: 4053
- Airframe hours: 726
- Engines: P&W PW150A 5071 horsepower
- Damage: No damage
- Flight: Part 121
- Operator: Horizon Airlines
- Departed: SEA, Seattle, WA
- Destination: BOI, Boise, ID

## Flight crew

- Pilot; age 49; airline transport; medical class 1; hours: 16,000 total, 50 total in this make and model

## Weather

- Conditions: Visual (VMC), Day
- Visibility (statute miles): 10
- Temperature (°F): 51.8

## Docket (2 files)

On NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=54292

- Supplement E (.PDF, 2 pages, 119 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40155542&FileExtension=.PDF&FileName=Supplement%20E-Master.PDF
- Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (.PDF, 6 pages, 251 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40391594&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

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From OpenAirDocs.org, an independent open copy of NTSB and FAA data. The NTSB's own report is the official record of an investigation.