# NTSB CHI88IA040: Boeing 747-251F, N618US, Minneapolis, MN, January 9, 1988

- Type: NTSB incident investigation
- Classification: Incident · No injuries · Incident investigation · Final report
- Date: January 9, 1988, 06:15 local (12:15 UTC)
- Place: Minneapolis, MN
- Coordinates: 44.880184, -93.200286 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=44.8802&lon=-93.2003&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 3 uninjured
- Status: Completed, report January 25, 1990
- Report: Approved by Office Director
- NTSB case key (mKey): 13983
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI88IA040
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/13983/pdf
- Page: https://openairdocs.org/ntsb/CHI88IA040

## Sequence of events

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

- Airframe/component/system failure/malfunction, cruise - normal
  - misc eqpt/furnishings - not secured (cause)
  - aircraft service - improper, other maintenance personnel (contributing factor)
  - flt control syst,aileron control cable/rod - movement restricted (cause)
  - flt control syst,aileron control cable/rod - ice (cause)

## Analysis

AIRCRAFT EXPERIENCED A LOSS OF AILERON CTL WHEN ICE FORMED AROUND AILERON CONTROL CABLES AND RESTRICTED THEIR MOVEMENT. WATER DRAINING THROUGH OPEN PLENUM DRAINS IN THE MAIN LANDING GEAR WHEEL WELL FROZE WHEN EXPOSED TO BELOW FREEZING TEMPERATURES AT 35,000 FT. THE FLIGHT CREW WAS ABLE TO REGAIN LIMITED CONTROL BY USING VERY HEAVY CONTROL INPUTS. THE ACFT WAS LANDED UNEVENTFULLY AFTER DIVERTING TO THE NEAREST SUITABLE AIRPORT. MAINTENANCE PERSONNEL REPORTED THAT THE DRAINS WERE INADVERTENTLY LEFT OPEN.

## Aircraft

- Registration: [N618US](https://openairdocs.org/aircraft/N618US), registered now, S/N 21122, built 1975 (OpenAirDocs)
- Reported make and model: BOEING 747-251F
- Registry model: [Boeing 747-251F](https://openairdocs.org/model/boeing-747-251f) (registry code 1384898) (OpenAirDocs)
- Registry engine: [Pratt & Whitney JT9D-3A](https://openairdocs.org/engine/pratt-whitney-jt9d-3a) (registry code 52050, turbo-fan) (OpenAirDocs)
- Category: Airplane
- Serial number: 21122
- Engines: P&W JT-9 19500 lbs thrust turbo fan
- Damage: No damage
- Flight: Part 121
- Operator: Northwest Airlines
- Registered owner: Northwest Airlines Inc.
- Airworthiness certificate: Standard, Transport
- Departed: JFK, NEW YORK, NY
- Destination: SEA, SEATTLE, WA
- Flight plan: IFR

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 45; airline transport; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, unknown; seat: left; flight hours: 19,190 total, 1,320 in this make and model

## Weather

- Conditions: Visual (VMC), Dawn
- Altimeter: 29.00 inHg

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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