# NTSB ANC91LA134: Cessna T-207A, N73762, Coville Lake, AK, August 25, 1991

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: August 24, 1991, 20:50 local (Aug 25, 1991, 04:50 UTC)
- Place: Coville Lake, AK
- Coordinates: 56.959877, -158.580413 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=56.9599&lon=-158.5804&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report May 5, 1993
- Report: Approved by Office Director
- NTSB office: Alaska Regional Office
- NTSB case key (mKey): 5609
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC91LA134
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/5609/pdf
- Page: https://openairdocs.org/ntsb/ANC91LA134

## Probable cause

A TOTAL FAILURE OF THE POWER OUTPUT SHAFT BOLTS DUE TO FATIGUE. CONTRIBUTING TO THE ACCIDENT WAS THE ROUGH AND UNEVEN TERRAIN.

## Sequence of events

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

- Loss of engine power(total) - mech failure/malf, maneuvering
  - turboshaft engine,power output shaft - failure,total (cause)
  - turboshaft engine,power output shaft - fatigue (cause)
- Forced landing, descent - emergency
- Dragged wing,rotor,pod,float or tail/skid, landing - roll
  - terrain condition - rough/uneven (contributing factor)

## Analysis

AFTER AN EMERGENCY LANDING ON A SMALL LAKE, THE AIRPLANE WAS SUBSTANTIALLY DAMAGED AND THE PILOT WAS NOT INJURED. EXAMINATION OF THE ENGINE REVEALED THE DRIVE SHAFT HAD BECOME DISCONNECTED FROM THE ENGINE DURING FLIGHT. FOUR OF THE FIVE DRIVE SHAFT COUPLING BOLTS FAILED DUE TO FATIGUE.

## Aircraft

- Registration: N73762 (not matched to a registry record)
- Reported make and model: CESSNA T-207A
- Category: Airplane
- Serial number: 624
- Airframe hours: 1708
- Engines: ALLISON 250-C-205 425 horsepower turbo prop
- Damage: Substantial damage
- Flight: Business, Part 91
- Registered owner: Katmailand, Inc.
- Airworthiness certificate: Standard, Normal
- Last inspection: 100 hour, July 28, 1991, 61 hours before

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 45; commercial, flight instructor; airplane ratings: single-engine land, multi-engine land, single-engine sea; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; seat: left; flight hours: 8,000 total, 900 in this make and model, 8,000 as pilot in command, 300 in the last 90 days, 100 in the last 30 days, 10 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 300° at 10 knots
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 64 °F
- Altimeter: 30.00 inHg

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Accident 19910824036629A](https://openairdocs.org/incident/19910824036629A), Aug 24, 1991: Cessna T207A, Coville Lake, AK, Substantial damage. Thomas coupling forward end driveshaft bolts failed. Pulled out of dive prior lake impact. Loose bolts were cause.

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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