# NTSB CHI93IA152: Boeing 767-233, Kansas City, MO, April 10, 1993

- Type: NTSB incident investigation
- Classification: Incident · No injuries · Incident investigation · Final report
- Date: April 10, 1993, 11:12 local (16:12 UTC)
- Place: Kansas City, MO
- Coordinates: 39.110332, -94.689208 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=39.1103&lon=-94.6892&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 101 uninjured
- Status: Completed, report May 10, 1994
- Report: Approved by Office Director
- NTSB case key (mKey): 15597
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI93IA152
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/15597/pdf
- Page: https://openairdocs.org/ntsb/CHI93IA152

## Probable cause

A FROZEN AILERON CONTROL BEARING AFTER IT HAD BECOME WORN, CORRODED AND EXPOSED TO WATER, AND THE MANUFACTURER'S INADEQUATE MAINTENANCE/INSPECTION REQUIRMENT OF THE BEARING(S).

## Sequence of events

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

- Airframe/component/system failure/malfunction, cruise
  - flt control syst,aileron control bearing - worn (cause)
  - flt control syst,aileron control bearing - corroded (cause)
  - flt control syst,aileron control bearing - frozen (cause)
  - maintenance,inspection - inadequate (cause)
  - procedure inadequate, manufacturer (cause)

## Analysis

THE FLIGHT CREW NOTED A LOSS OF AILERON CONTROL (FELT FROZEN), WHILE CRUISING AT FL 370. THEY WERE ABLE TO MAKE HEADING CHANGES BY USING THE RUDDER & ELECTED TO DIVERT TO KANSAS CITY (MCI).  THE AIRPLANE HAD BEEN EXPOSED TO RAIN & STANDING WATER BEFORE THE FLIGHT.  THE CREW FELT THE LOSS OF AILERON CONTROL MAY HAVE BEEN DUE TO FROZEN WATER IN THE CONTROL SYSTEM. DURING DESCENT TO MCI, ABOVE FREEZING AIR TEMPERATURES WERE ENCOUNTERED, & CONTROL OF THE AILERONS GRADUALLY RETURNED UNTIL FULL CONTROL WAS REGAINED.  AN UNEVENTFUL LANDING WAS MADE AT MCI.  INVESTIGATION REVEALED WORN AILERON CONTROL BEARINGS IN THE LATERAL CONTROL ACTUATOR SYSTEM.  THE WORN BEARINGS WERE TESTED BY SOAKING IN WATER & FREEZING. WATER PENETRATED A BEARING HOUSING & FROZE INSIDE THE BEARING RACE, DISABLING THE BEARING. SUBSEQUENT DISASSEMBLY OF THE BEARING DISCLOSED CORRODED & WORN BALL BEARINGS. BOEING SERVICE LETTER (767-S-27-094) & SEVICE BULLETIN 767-27-0128 WERE ISSUED TO ADDRESS INSPECTION/REPLACEMENT CRITERIA OF THE BEARINGS.

## Aircraft

- Registration: CGAUP (not matched to a registry record)
- Reported make and model: BOEING 767-233
- Category: Airplane
- Serial number: 22521
- Airframe hours: 32301
- Engines: P&W JT9D-7R4D 48000 lbs thrust turbo fan
- Damage: No damage
- Flight: Part 129
- Operator: Air Canada
- Registered owner: Air Canada
- Airworthiness certificate: Standard, Transport
- Last inspection: Continuous airworthiness, January 2, 2000
- Departed: SFO, SAN FRANCISCO, CA
- Destination: YYZ, TORONTO
- Flight plan: IFR

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; airline transport; airplane ratings: multi-engine land; instrument ratings: airplane; medical: unknown, unknown; seat: left

## Weather

- Conditions: Visual (VMC), Day
- Visibility: 50 statute miles
- Lowest ceiling: none
- Temperature: -69 °F
- 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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