# NTSB DEN91IA076: Aero Commander 690C, N81TR, Denver, CO, May 24, 1991

- Type: NTSB incident investigation
- Classification: Incident · No injuries · Incident investigation · Final report
- Date: May 23, 1991, 20:25 local (May 24, 1991, 02:25 UTC)
- Place: Denver, CO
- Coordinates: 39.730613, -104.919944 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=39.7306&lon=-104.9199&mi=10
- Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report May 5, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 18043
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN91IA076
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/18043/pdf
- Page: https://openairdocs.org/ntsb/DEN91IA076

## Probable cause

FATIGUE FAILURE OF FLAP CABLE.

## Sequence of events

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

- Airframe/component/system failure/malfunction, approach - vfr pattern - base leg/base to final
  - flt control syst,wing flap control cable/rod - fatigue (cause)

## Analysis

DURING MID-BASE LEG FOR A VFR APPROACH TO LANDING AT STAPELTON INTERNATIONAL AIRPORT, THE PILOT OF N81TR WAS SELECTING FULL FLAP POSITION, WHEN HE HEARD A DULL THUD.  THE AIRCRAFT STARTED A ROLL TO THE LEFT, BUT THE PILOT WAS ABLE TO MAINTAIN CONTROL OF THE AIRCRAFT UNITL HE COULD RAISE THE FLAP HANDLE.  AFTER SELECTING 'FLAP UP POSITION,'  THE AIRCRAFT RETURNED TO NORMAL FLIGHT, AND A NORMAL NO FLAP LANDING WAS ACCOMPLISHED.  AFTER LANDING, THE AIRCRAFT WAS PARKED AND INSPECTED.  A BROKEN FLAP CABLE WAS FOUND.  LATER, TESTS REVEALED THE CABLE HAD SEPARATED DUE TO FATIGUE.

## Aircraft

- Registration: [N81TR](https://openairdocs.org/deregistered/N81TR-1993-02-09), registration cancelled 1993-02-09, S/N 11690 (OpenAirDocs)
- Reported make and model: AERO COMMANDER 690C
- Registry model: [Rockwell International 690C](https://openairdocs.org/model/rockwell-international-690c) (registry code 7630517) (OpenAirDocs)
- Category: Airplane
- Serial number: 11690
- Engines: GARRETT TPE331-5-254K 717 horsepower turbo prop
- Damage: No damage
- Flight: Part 135
- Operator: Casper Air Service
- Registered owner: Casper Air Service
- Departed: CYS, CHEYENNE, WY
- Destination: DEN, DENVER, CO
- Flight plan: Unknown
- Airport: DEN, Stapleton International, runway 18, 7,700 × 150 ft, asphalt

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 35; airline transport; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; flight hours: 3,215 total, 380 in this make and model, 3,081 as pilot in command, 70 in the last 90 days, 35 in the last 30 days, 2 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Dusk
- Wind: 180° at 5 knots
- Visibility: 15 statute miles
- Lowest ceiling: none
- Temperature: -0 °F, dew point -0 °F

## 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 19910523031649I](https://openairdocs.org/incident/19910523031649I), May 23, 1991: Gulstm 690C, Denver, CO, Minor damage. Heard thud when flaps came down. Aircraft rolled. Put flaps up and landed with no further problems.

## Other investigations on N81TR (1)

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.

- [NTSB DEN93FA017](https://openairdocs.org/ntsb/DEN93FA017), Dec 23, 1992: Rockwell 690C (N81TR), Golden, CO, destroyed, 1 fatal. Probable cause: THE PILOT FLYING THE AIRCRAFT BEYOND THE DESIGN MANEUVERING SPEED AND EXCEEDING THE DESIGN STRESS LIMITS. A FACTOR WAS: CLEAR AIR TURBULENCE.

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.

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.