# NTSB SEA92LA082: Beech B36TC, N7252X, Mona, UT, April 22, 1992

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: April 21, 1992, 18:45 local (Apr 22, 1992, 00:45 UTC)
- Place: Mona, UT
- Coordinates: 39.850173, -111.840621 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=39.8502&lon=-111.8406&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report August 13, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 41661
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA92LA082
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/41661/pdf
- Page: https://openairdocs.org/ntsb/SEA92LA082

## Probable cause

A FATIGUE FAILURE TO THE CRANKSHAFT AND A MANUFACTURING MATERIAL DEFECT.

## 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
  - engine assembly,crankshaft - fatigue (cause)
  - material defect, manufacturer (cause)
- Forced landing, descent - emergency
- On ground/water encounter with terrain/water, landing - roll
  - terrain condition - ditch

## Analysis

DURING A CROSS COUNTRY FLIGHT, THE PILOT REPORTED THAT THE ENGINE LOST POWER WHILE IN CRUISE FLIGHT. THE PILOT DECLARED AN EMERGENCY AND INITIATED A FORCED LANDING TO AN OPEN FIELD. DURING THE LANDING ROLL, THE AIRPLANE COLLIDED WITH A DITCH. DURING AN ENGINE EXAMINATION, IT WAS FOUND THAT THE CRANKSHAFT WAS BROKEN BETWEEN THE NUMBER TWO MAIN JOURNAL, EXTENDING TO THE NUMBER TWO MAIN JOURNAL CHEEK AND NUMBER TWO CONNECTING ROD JOURNAL. A METALLURGICAL EXAMINATION REVEALED AN OCCLUDED MATERIAL WHICH APPEARED TO BE OXIDES OR OTHER NON METALLIC INCLUSIONS PRODUCED DURING THE MANUFACTURE OF THE METAL PRIOR TO FORGING. THE METALLURGICAL REPORT STATED,'THESE OXIDES MOST LIKELY PROVIDED STRESS RISERS WHICH CONCENTRATED STRESSES IN THE CRANKSHAFT TO DEVELOP CRACKS UNDER CYCLIC LOADING.' THE CRACKS PROPAGATED UNTIL FAILURE OCCURRED.

## Aircraft

- Registration: [N7252X](https://openairdocs.org/deregistered/N7252X-2004-11-01), registration cancelled 2004-11-01, S/N EA-450, built 1985 (OpenAirDocs)
- Reported make and model: BEECH B36TC
- Registry model: [Beech B36TC](https://openairdocs.org/model/beech-b36tc) (registry code 1151609) (OpenAirDocs)
- Registry engine: [Continental TSIO-520 series](https://openairdocs.org/engine/continental-tsio-520-series) (registry code 17040, reciprocating) (OpenAirDocs)
- Category: Airplane
- Serial number: EA-450
- Airframe hours: 1248
- Engines: CONTINENTAL TSIO-520-UB 300 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Operator: Bodell, Michael J.
- Registered owner: Bodell, Michael J.
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, June 21, 1991, 122 hours before
- Departed: MT CARMEL, UT
- Destination: SLC, SALT LAKE CITY, UT

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 42; private; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 3, valid medical--w/ waivers/lim; seat: left; flight hours: 1,398 total, 319 in this make and model, 1,277 as pilot in command, 38 in the last 90 days, 14 in the last 30 days, 3 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 90° at 10 knots
- Visibility: 20 statute miles
- Temperature: 64 °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).

- [Accident 19920421018879A](https://openairdocs.org/incident/19920421018879A), Apr 21, 1992: Beech B36TC, Mona, UT, Substantial damage. Lost power en route. Landing, collided with a ditch. Crankshaft broke. Oxides used in manufacture caused stress crack

## Other investigations on N7252X (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 FTW04FA062](https://openairdocs.org/ntsb/FTW04FA062), Jan 16, 2004: Beech B36TC (N7252X), Willow Park, TX, destroyed, 1 fatal. Probable cause: The pilot's failure to maintain aircraft control while maneuvering. Contributing factors were the dark night and rain.

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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