# NTSB FTW85LA233: Mooney M20, N853B, Hamilton, TX, May 24, 1985

- Type: NTSB accident investigation
- Classification: Accident · Serious injuries · Limited investigation · Final report
- Date: May 24, 1985, 09:35 local (14:35 UTC)
- Place: Hamilton, TX
- Coordinates: 31.700206, -98.120857 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=31.7002&lon=-98.1209&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: Serious injuries
- Injuries: 1 serious
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 21758
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW85LA233
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/21758/pdf
- Page: https://openairdocs.org/ntsb/FTW85LA233

## Sequence of events

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

- Loss of engine power, cruise - normal
  - propeller system/accessories - vibration (cause)
  - lubricating system,oil seal - undertorqued (cause)
  - fluid,oil - loss,partial (cause)
  - lubricating system,oil gasket - undertorqued (cause)
- Forced landing, descent - emergency
- Undershoot, descent - emergency
- Hard landing, descent - emergency

## Analysis

THE PLT STATED THE ACFT AND ENGINE ASSY HAD EXPERIENCED EXECSSIVE VIBRATIONS WHILE IN FLT FOLLOWED BY THE WINDSHIELD BEING COVERED WITH OIL IMMEDIATELY AFTER THE VIBRATION STARTED. THE PROPELLER ASSY HAD BECOME LOOSE FROM THE ENGINE MOUNT AND SEPARATED AT IMPACT. ONLY ONE BOLT REMAINED ATTACHED AT IMPACT. METALLURGICAL EXAM INDICATED A LACK OF TORQUE WHICH ALLOWED VIBRATORY AND OTHER HIGH CYCLE STRESS TO BE FELT BY THE BOLTS THEREBY INITIATING AND PROPAGATING FATIQUE CRACKS.

## Aircraft

- Registration: N853B (not matched to a registry record)
- Reported make and model: MOONEY M20
- Category: Airplane
- Serial number: 1014
- Airframe hours: 2180
- Engines: LYCOMING O-320 150 horsepower reciprocating
- Damage: Destroyed
- Flight: Personal, Part 91
- Registered owner: Jrery C. Tongate
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, December 1, 1984, 40 hours before
- Departed: 68F, TEAGUE, TX
- Destination: BWD, BROWNWOOD, TX
- Airport: T21, Hamilton Municipal, runway 35, 3,545 × 50 ft, asphalt

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 57; student; medical: class 3, valid medical--w/ waivers/lim; seat: left; flight hours: 45 total, 45 in this make and model, 20 as pilot in command, 10 in the last 90 days, 1 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Visibility: 15 statute miles
- Lowest ceiling: none
- Temperature: 75 °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 19850524020979A](https://openairdocs.org/incident/19850524020979A), May 24, 1985: Mooney M20, Hamilton, TX, Destroyed. Forced landing short of runway after vibration in engine and oil on windshield. Propeller bolts improperly torqued.

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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