# NTSB ATL92LA010: Beech A36, N3735Y, Selma, AL, October 17, 1991

- Type: NTSB accident investigation
- Classification: Accident · Minor injuries · Limited investigation · Final report
- Date: October 17, 1991, 16:45 local (21:45 UTC)
- Place: Selma, AL
- Coordinates: 32.409679, -87.030494 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=32.4097&lon=-87.0305&mi=10
- Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping)
- Highest injury: Minor injuries
- Injuries: 1 minor
- Status: Completed, report July 14, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 8537
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ATL92LA010
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/8537/pdf
- Page: https://openairdocs.org/ntsb/ATL92LA010

## Probable cause

THE FATIGUE FAILURE OF THE ENGINE CRANKSHAFT COUNTERWEIGHT BLADE, WHICH RESULTED FROM EXCESSIVE WEAR OF THE COUNTERWEIGHT PIN BUSHINGS, DUE TO CORROSION FROM AN UNKNOWN SOURCE.

## 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, approach - vfr pattern - final approach
  - eng assembly,crankshaft counterweights/vib damper - corroded (cause)
  - eng assembly,crankshaft counterweights/vib damper - fatigue (cause)
  - eng assembly,crankshaft counterweights/vib damper - previous damage (cause)
- Forced landing, cruise
  - planned approach - improper, pilot in command (contributing factor)
- On ground/water encounter with terrain/water, landing - roll

## Analysis

DURING CRUISE FLIGHT, THE ENGINE RPM DECREASED, MOMENTARILY. THE PILOT LANDED AND A MECHANIC CHECKED THE ENGINE. NO ANOMALIES WERE FOUND. A POST MAINTENANCE FLIGHT, IN THE LANDING PATTERN, WAS FLOWN TO VERIFY ENGINE OPERATION. ON FINAL APPROACH, THE ENGINE QUIT, AND THE AIRPLANE WAS LANDED IN ROUGH TERRAIN SHORT OF THE RUNWAY. EXAMINATION OF THE ENGINE REVEALED THAT THE NUMBER 2 CHECK COUNTERWEIGHT BLADE WAS FRACTURED. METALLURGICAL EXAMINATION DISCOVERED CORROSION PITTING ON THE INNER DIAMETER OF THE COUNTERWEIGHT PIN BUSHINGS, AS WELL AS EXCESSIVE INNER DIAMETER WEAR. THE COUNTERWEIGHT BLADE FRACTURE EXHIBITED EVIDENCE OF FATIGUE. A LOG BOOK ENTRY INDICATED THAT THE ENGINE HAD BEEN PREVIOUSLY DISASSEMBLED FOR EXAMINATION FOLLOWING A LIGHTNING STRIKE. THERE WAS NO RECORD OF AN ENGINE OVERHAUL. THE SAFETY BOARD BELIEVES THAT THE COUNTERWEIGHT FAILED IN FATIGUE, BECAUSE OF PREVIOUS PITTING DAMAGE TO THE BUSHINGS, FROM AN UNKNOWN SOURCE.

## Aircraft

- Registration: [N3735Y](https://openairdocs.org/deregistered/N3735Y-2013-11-12), registration cancelled 2013-11-12, S/N E-1767, built 1980 (OpenAirDocs)
- Reported make and model: BEECH A36
- Registry model: [Beech A36](https://openairdocs.org/model/beech-a36) (registry code 1151604) (OpenAirDocs)
- Registry engine: [Continental IO-520 series](https://openairdocs.org/engine/continental-io-520-series) (registry code 17032, reciprocating) (OpenAirDocs)
- Category: Airplane
- Serial number: E-1767
- Airframe hours: 3070
- Engines: CONTINENTAL IO-520-BB 285 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Operator: Gray, Thomas L.
- Registered owner: Gray, Thomas L.
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, July 17, 1991, 68 hours before
- Airport: SEM, Craig Field, runway 14, 8,002 × 150 ft, asphalt

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 31; private; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 3, valid medical--no waivers/lim.; seat: left; flight hours: 358 total, 155 in this make and model, 271 as pilot in command, 52 in the last 90 days, 24 in the last 30 days, 2 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: calm
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 75 °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 19911017046849A](https://openairdocs.org/incident/19911017046849A), Oct 17, 1991: Beech A36, Selma, AL, Substantial damage. Threw connecting rod on test flight. Crashed short of runway. Engine had recent inspection. Lost counterweight.

## Other investigations on N3735Y (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 CHI84LA173](https://openairdocs.org/ntsb/CHI84LA173), May 2, 1984: Beech A36 (N3735Y), Minneapolis, MN, substantial damage

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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