# NTSB CHI89IA083: Mcdonnell Douglas DC-9-82, N434AA, Minneapolis, MN, May 2, 1989

- Type: NTSB incident investigation
- Classification: Incident · No injuries · Incident investigation · Final report
- Date: May 2, 1989, 14:40 local (19:40 UTC)
- Place: Minneapolis, MN
- Location: 44.9800° N, 93.2638° W: Placed by OpenAirDocs: center of Minneapolis, MN, within about 6 miles (OpenAirDocs)
- Nearby events: https://openairdocs.org/map.md?lat=44.9800&lon=-93.2638&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 96 uninjured
- Status: Completed, report August 26, 1992
- Report: Approved by Office Director
- Safety recommendations: Yes
- NTSB case key (mKey): 14282
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI89IA083
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/14282/pdf
- Page: https://openairdocs.org/ntsb/CHI89IA083

## Probable cause

FAILURE OF THE HYDRAULIC POWER TRANSFER UNIT SHUT-OFF (PTU S/O) VALVE DUE TO FAILED (FATIGUED) VALVE BODY ATTACH SCREWS.

## 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,shutoff valve - failure,total (cause)
  - hydraulic system - no pressure (cause)
- On ground/water encounter with terrain/water, landing - flare/touchdown
  - terrain condition - runway (cause)
  - hydraulic system - unavailable (cause)

## Aircraft

- Registration: [N434AA](https://openairdocs.org/deregistered/N434AA-2019-09-16), registration cancelled 2019-09-16, S/N 49452, built 1987 (OpenAirDocs)
- Reported make and model: MCDONNELL DOUGLAS DC-9-82
- Registry model: [Mcdonnell Douglas DC-9-83(MD-83)](https://openairdocs.org/model/mcdonnell-douglas-dc-9-83-md-83) (registry code 3022083) (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: 49452
- Engines: P&W JT8D-217A 14500 lbs thrust turbo fan
- Damage: Minor damage
- Flight: Part 121
- Registered owner: American Airlines
- Airworthiness certificate: Standard, Transport
- Departed: SEA, SEATTLE, WA
- Destination: ORD, CHICAGO, IL
- Flight plan: IFR
- Airport: MSP, Minneapolis St Paul Intl, runway 29L, 10,000 × 200 ft, asphalt

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 39; airline transport; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; seat: left; flight hours: 7,450 total, 150 in the last 90 days, 50 in the last 30 days, 2 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 290° at 9 knots
- Visibility: 20 statute miles
- Lowest ceiling: 7,000 ft broken
- Temperature: 55 °F, dew point 27 °F
- Altimeter: 30.00 inHg
- Observed at: MSP

## 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 19890502036339I](https://openairdocs.org/incident/19890502036339I), May 2, 1989: Doug DC982, Minneapolis, MN, Minor damage. Fluid quantity in both hydraulic systems went to 0. Manually extended gear. Power transfer valve assembly broke.

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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