# NTSB CHI98IA167: McDonnell Douglas MD82, N951U, Washington, DC, April 11, 1998

- Type: NTSB incident investigation
- Classification: Incident · No injuries · Incident investigation · Final report
- Date: April 11, 1998, 06:45 local (11:45 UTC)
- Place: Washington, DC
- Coordinates: 38.930423, -77.030189 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=38.9304&lon=-77.0302&mi=10
- Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 84 uninjured
- Status: Completed, report November 29, 2000
- Report: Approved by Office Director
- NTSB case key (mKey): 10751
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI98IA167
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/10751/pdf
- Page: https://openairdocs.org/ntsb/CHI98IA167

## Probable cause

The failure of the Dual Axis Accelerometer.

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- Airframe/component/system failure/malfunction, takeoff - initial climb
  - autopilot/flight director,amplifier and computer - failure (cause)

## Analysis

The Douglas MD82 experienced a flight control malfunction after takeoff and diverted to Dulles International Airport. The crew reported that they lost the autopilot, there were in-flight kicks on the rudder and the rudder tab was moving uncommanded on the ground. The Yaw Damper Actuator, Digital Flight Guidance Computer, and Dual Axis Accelerometer were removed for further testing.  The Yaw Damper Actuator and the Digital Flight Guidance Computer passed testing.  The Dual Axis Accelerometer was bench tested using test manual #22-19-01, Rev 1 at the avionics test center.  The unit failed an original test and failed a second test after a metal sliver  imbedded in the pins was removed.

## Factual narrative

On April 11, 1998, at 0645 est, N951U, a McDonnell Douglas MD82, being operated as Trans World Airlines flight number 235, from Washington National Airport to Saint Louis, Missouri, experienced a flight control malfunction after takeoff and diverted to Dulles International Airport.  There was no damage to the aircraft and there were no injuries to the crew of 5 or 79 passengers.  The flight was on an IFR flight plan and visual meteorological conditions prevailed.

The crew reported that they lost the autopilot, there were inflight kicks on the rudder and the rudder tab was moving uncommanded on the ground.  The aircraft was an MD-82, S/N 49245.  The Yaw Damper Actuator, Digital Flight Guidance Computer, and Dual Axis Accelerometer were removed for further testing.  The Yaw Damper Actuator and the Digital Flight Guidance Computer passed testing.

The Dual Axis Accelerometer from the aircraft, PN 4034239-901, SN 8303033, was taken to the Honeywell Support Center in Dallas, Texas for further investigation.  The part was bench tested using test manual #22-19-01, Rev 1 at the avionics test center.  The unit failed an original test and failed a second test after a metal sliver  imbedded in the pins was removed.  See attached test report of the inspection conducted July 8, 1998.

## Aircraft

- Registration: [N951U](https://openairdocs.org/deregistered/N951U-2011-01-06), registration cancelled 2011-01-06, S/N 49245, built 1984 (OpenAirDocs)
- Reported make and model: McDonnell Douglas MD82
- Registry model: [Mcdonnell Douglas DC-9-82(MD-82)](https://openairdocs.org/model/mcdonnell-douglas-dc-9-82-md-82) (registry code 3022082) (OpenAirDocs)
- Registry engine: [Pratt & Whitney JT8D series](https://openairdocs.org/engine/pratt-whitney-jt8d-series) (registry code 52053, turbo-jet) (OpenAirDocs)
- Category: Airplane
- Serial number: 49245
- Engines: unknown
- Damage: No damage
- Flight: Part 121
- Operator: Trans World Airlines, doing business as Twa
- Registered owner: Trans World Airlines
- Airworthiness certificate: Standard, Transport
- Destination: STL, SAINT LOUIS, MO
- Flight plan: IFR

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; airline transport; medical: unknown, unknown; seat: left

## Weather

- Conditions: Visual (VMC), Not reported

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.

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