# NTSB ATL94LA158: Cessna 172XP, N9797V, Clarksburg, TN, August 19, 1994

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: August 19, 1994, 17:40 local (22:40 UTC)
- Place: Clarksburg, TN
- Location: 35.8705° N, 88.3937° W: Placed by OpenAirDocs: center of Clarksburg, TN, within about 6 miles (OpenAirDocs)
- Nearby events: https://openairdocs.org/map.md?lat=35.8705&lon=-88.3937&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report March 13, 1995
- Report: Approved by Office Director
- Safety recommendations: Yes
- NTSB case key (mKey): 3434
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ATL94LA158
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/3434/pdf
- Page: https://openairdocs.org/ntsb/ATL94LA158

## Probable cause

THE FAILURE OF THE ALTERNATOR DRIVE COUPLING, AND DEBRIS FROM THE FAILED COUPLING THAT LODGED IN THE ENGINE OIL PUMP, RESULTING IN  A SHEARED OIL PUMP DRIVE SHAFT. THE ENGINE SUBSEQUENTLY FAILED BECAUSE OF OIL STARVATION.

## 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, cruise - normal
  - electrical system,drive/belt - failure,total (cause)
  - lubricating system,oil pressure pump - foreign object damage
  - lubricating system,oil pressure pump - disabled
  - fluid,oil - starvation
- Forced landing, descent - emergency
- On ground/water collision with object, landing - roll
  - object - tree(s)

## Analysis

WHILE EN ROUTE TO HIS DESTINATION AIRPORT, THE PILOT EXPERIENCED COMPLETE LOSS OF ENGINE POWER. THE PILOT SELECTED A PASTURE AND MADE AN EMERGENCY LANDING. DURING THE ROLLOUT, THE AIRPLANE COLLIDED WITH TREES ALONG A FENCE LINE. EXAMINATION OF THE ENGINE DISCLOSED THAT THE ALTERNATOR DRIVE COUPLING FAILED, AND DEBRIS FROM THE COUPLING LODGED IN THE ENGINE OIL PUMP DRIVE; THE ENGINE EXPERIENCED A LOSS OF ENGINE OIL PRESSURE.

## Factual narrative

On August 19, 1994, at 1740 central daylight time, a Cessna, N9797V, collided with trees while attempting an emergency landing in a pasture near Clarksburg, Tennessee. The business flight operated under the provisions of 14 CFR Part 91 with a visual flight plan filed. Visual weather conditions prevailed at the time of the accident. The aircraft received substantial damage, the pilot was not injured. The flight departed Nashville, Tennessee, at 1640 hours.

According to the pilot, while flying at 2500 feet enroute to his destination airport, the engine sputtered twice and lost power. After the second occurrence, the pilot selected a pasture for an emergency landing. During the landing rollout, the airplane collided with a fence and trees.

The engine examination revealed that the engine sustained oil starvation damage. Steel and rubber debris from internal engine components were recovered from the engine oil sump. The examination also revealed that the alternator drive gear had sheared and was lodged in the accessary pad opening; the engine oil pump drive shaft had also sheared (see attached inspector's statement).

## Aircraft

- Registration: [N9797V](https://openairdocs.org/deregistered/N9797V-1994-11-03), registration cancelled 1994-11-03, S/N R1722350 (OpenAirDocs)
- Reported make and model: CESSNA 172XP
- Registry model: [Cessna R172K](https://openairdocs.org/model/cessna-r172k) (registry code 2072431) (OpenAirDocs)
- Category: Airplane
- Serial number: 1722350
- Airframe hours: 1087
- Engines: CONTINENTAL IO-360-K 195 horsepower reciprocating
- Damage: Substantial damage
- Flight: Business, Part 91
- Registered owner: Bryan, Thomas E. Sr
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, August 31, 1993, 60 hours before
- Departed: JWN, NASHVILLE, TN
- Destination: OLV, MEMPHIS, TN
- Flight plan: VFR

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 64; private; airplane ratings: single-engine land; medical: class 3, valid medical--no waivers/lim.; seat: left; flight hours: 1,238 total, 100 in this make and model, 17 in the last 90 days, 7 in the last 30 days, 1 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 220° at 5 knots
- Visibility: 12 statute miles
- Lowest ceiling: 25,000 ft overcast
- Temperature: 88 °F, dew point 70 °F
- Altimeter: 29.00 inHg
- Observed at: MKL

## 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 19940819022509A](https://openairdocs.org/incident/19940819022509A), Aug 19, 1994: Cessna R172K, Clarksburg, TN, Substantial damage. Lost power en route. Land in pasture hit trees. Alternator drive coupling failed. Debris failed oil pump. Lost oil.

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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