Casper Air Service Aero Commander 690C incident
Aero Commander 690C · Incident: airframe, component or system failure on approach
From Cheyenne Regional Jerry Olson Field (CYS) to Denver International Airport (DEN)
Event
- NTSB case
- DEN91IA076
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Incident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 0 · all aircraft and ground
- Ground fatalities
- 0
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- Charter & commuter
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
Aero Commander 690C
- Aircraft type
- Aero Commander 690
- Category
- Airplane
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N81TR
- Operator
- Casper Air Service
- Onboard fatalities
- Unknown
- Route
- From Cheyenne Regional Jerry Olson Field (CYS), Cheyenne, WYTo Denver International Airport (DEN), Denver, CO
- Aircraft age
- Not recorded
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 135: Air Taxi & Commuter
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- Approach · VFR pattern base
- First occurrenceThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- Airframe, component or system failure
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- None
Cause areas
- Flt control syst, wing flap control cable/rod › Fatigue
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
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.
Probable cause
FATIGUE FAILURE OF FLAP CABLE.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record DEN91IA076
- Event ID
- 20001212X16978
- Case number
- DEN91IA076
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: local date, investigation status, damage. Values present in the bulk record are kept.
- The date is the local date; the NTSB stores the UTC date 1991-05-24.
- API snapshot SHA-256: 28ff3889db1574948e09b584308f38864f5fcb22c81e906d41f8d15fe7aa770f; retrieved 2026-09-18T18:54:52.466Z.