# NTSB CHI88IA129: Short Brothers SD3-60, N383MQ, Madison, WI, June 3, 1988

- Type: NTSB incident investigation
- Classification: Incident · No injuries · Incident investigation · Final report
- Date: June 3, 1988, 18:25 local (23:25 UTC)
- Place: Madison, WI
- Coordinates: 43.100036, -89.31015 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=43.1000&lon=-89.3101&mi=10
- Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 21 uninjured
- Status: Completed, report June 11, 1990
- Report: Approved by Office Director
- NTSB case key (mKey): 13995
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI88IA129
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/13995/pdf
- Page: https://openairdocs.org/ntsb/CHI88IA129

## Probable cause

FAILURE OF THE RIGHT OUTBOARD FLAP POSITION SIGNALLING CABLE DUE TO CHAFFING INITIATED BY IMPROPER INSTALLATION/RIGGING BY A MANUFACTURER'S VENDOR.

## Sequence of events

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

- Airframe/component/system failure/malfunction, approach - iaf to faf/outer marker (ifr)
  - flt control syst,wing flap control cable/rod - failure,total
  - aircraft control - restricted, pilot in command
  - inadequate surveillance,insufficient staff, manufacturer (cause)
  - flt control syst,wing flap control cable/rod - chafed (cause)

## Analysis

WHILE ON A STABILIZED FINAL APPROACH, THE PILOT EXPERIENCED AN UNCOMMANDED RIGHT ROLL WHEN THE FLAP SETTING WAS INCREASED FROM FIVE TO FIFTEEN DEGREES. THE CONDITION WAS ALLEVIATED WHEN THE FLAPS WERE RESET TO FIVE DEGREES. POST FLIGHT INSPECTION REVEALED THAT THE RIGHT OUTBOARD FLAP POSITION SIGNALLING CABLE HAD FAILED. INSPECTION OF THE OPERATOR'S FLEET FOUND TWO ADDITIONAL AIRCRAFT WITH CHAFFED/FRAYED FLAP POSITION SIGNALLING CABLES. ALL CHAFFED/FRAYED CABLES WERE INSTALLED ON AIRCRAFT WHICH THE OPERATOR HAD PURCHASED AS A SERIES. ON THIS SERIES OF AIRCRAFT THE FLAPS AND CONTROL RIGGING WERE INSTALLED BY THE VENDOR WHICH MANUFACTURES THE WINGS, RATHER THAN THE MANUFACTURER OF THE AIRFRAME, AS IS NORMALLY THE CASE.

## Aircraft

- Registration: [N383MQ](https://openairdocs.org/aircraft/N383MQ), registered now, S/N SH3706 (OpenAirDocs)
- Reported make and model: SHORT BROTHERS SD3-60
- Registry model: [Short Bros SD3-60](https://openairdocs.org/model/short-bros-sd3-60) (registry code 8100606) (OpenAirDocs)
- Category: Airplane
- Serial number: SH3706
- Airframe hours: 3413
- Engines: P&W PT6A-65AR 1424 horsepower turbo prop
- Damage: No damage
- Flight: Part 121
- Operator: Simmons Airlines, doing business as American Eagle
- Registered owner: U.S. West Financial Serv. Inc
- Airworthiness certificate: Standard, Transport
- Last inspection: Continuous airworthiness, May 26, 1988, 50 hours before
- Departed: ORD, CHICAGO, IL
- Destination: MSN, MADISON, WI
- Flight plan: IFR
- Airport: runway 36, 9,000 × 150 ft, concrete

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; private, commercial; airplane ratings: single-engine land; medical: class 1, unknown; seat: left

## Weather

- Conditions: Visual (VMC), Day
- Wind: 10° at 8 knots
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 73 °F, dew point 37 °F
- Altimeter: 30.00 inHg
- Observed at: MSN, 1 nm away

## 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 19880603071479I](https://openairdocs.org/incident/19880603071479I), Jun 3, 1988: Stbros SD360, Madison, WI. Flap cable broke on right wing on flap extension for landing causing split flaps. Reduced flaps and landed safely.

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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