# NTSB CHI87IA026: Boeing 757-251, N516US, Washington, DC, November 6, 1986

- Type: NTSB incident investigation
- Classification: Incident · No injuries · Incident investigation · Final report
- Date: November 5, 1986, 22:00 local (Nov 6, 1986, 03:00 UTC)
- Place: Washington, DC
- Location: 38.8951° N, 77.0364° W: Placed by OpenAirDocs: center of Washington, DC, within about 6 miles (OpenAirDocs)
- Nearby events: https://openairdocs.org/map.md?lat=38.8951&lon=-77.0364&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 188 uninjured
- Status: Completed, report April 25, 1988
- Report: Approved by Office Director
- Safety recommendations: Yes
- NTSB case key (mKey): 13659
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI87IA026
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/13659/pdf
- Page: https://openairdocs.org/ntsb/CHI87IA026

## Sequence of events

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

- Airframe/component/system failure/malfunction, climb - to cruise
  - flt control syst,aileron control - other
  - acft/equip,inadequate design, manufacturer (cause)
  - weather condition - rain (contributing factor)
  - weather condition - temperature extremes (contributing factor)
  - flt control syst,aileron control - frozen (cause)

## Analysis

DRG AN EN ROUTE CLIMB, AILERON CONTROL (CTL) BCM PROGRESSIVELY MORE STIFF. AT CRUISE ALT, THE AUTOPLT DISENGAGED & THE AILERONS WOULD NOT MOVE. AILERON CTL WAS RESTORED AFTER A DSCNT BELOW THE FREEZING LEVEL. THE ACFT WAS FLOWN BELOW THE FREEZING LVL FOR THE REMAINDER OF THE FLT. A POST-FLT MAINT INSPN REVEALED NO PHYSICAL EVIDENCE FOR THE TEMPORARY LOSS OF AILERON CTL. AN INVESTIGATION REVEALED THAT BEFORE TAKEOFF, THE ACFT WAS EXPOSED TO RAIN FOR ABOUT 50 MIN WHILE PARKED AT A GATE. THE TEMPERATURE IN WASHINGTON WAS IN THE MID 40'S. THE OPERATOR SUSPECTED ICE BUILD-UP ON THE AILERON CABLES. THE MANUFACTURER HAD ISSUED A SERVICE BULLETIN (SB) (SB B-757-0079) TO REMOVE THE AILERON CABLE GROMMETS & APPLYA SEALANT TO ELIMINATE THE PROBLEM. THE SB HAD BEEN COMPLIED WITH. AFTER THE INCIDENT, A REVISED SB, DATED 11/6/86, WAS ISSUED TO REPLACE THE AILERON CABLE GROMMETS WITH NEW GROMMETS WITH INCREASED INTERNAL DIAMETER. ALSO, AN OPNS MANUAL BULLETIN (NUMBER 87-1) WAS ISSUED ON 1/22/87 TO ADVISE FLT CREWS.

## Aircraft

- Registration: [N516US](https://openairdocs.org/deregistered/N516US-2017-07-21), registration cancelled 2017-07-21, S/N 23204, built 1986 (OpenAirDocs)
- Reported make and model: BOEING 757-251
- Registry model: [Boeing 757-251](https://openairdocs.org/model/boeing-757-251) (registry code 1384970) (OpenAirDocs)
- Registry engine: [Amateur-built UNKNOWN ENG](https://openairdocs.org/engine/amateur-built-unknown-eng) (registry code 99999) (OpenAirDocs)
- Category: Airplane
- Serial number: 23204
- Engines: P&W 2037 3700 lbs thrust turbo fan
- Damage: No damage
- Flight: Part 121
- Registered owner: Northwest Orient Airlines
- Airworthiness certificate: Standard, Normal
- Departed: DCA, WASHINGTON, DC
- Destination: MSP, MINNEAPOLIS, MN
- Flight plan: IFR

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 48; airline transport; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; seat: left; flight hours: 10,000 total

## Weather

- Conditions: Visual (VMC), Night/dark

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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