# NTSB LAX91LA135: Mooney M20D, N1921Y, Herlong, CA, March 18, 1991

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: March 17, 1991, 16:30 local (Mar 18, 1991, 00:30 UTC)
- Place: Herlong, CA
- Coordinates: 40.139671, -120.160484 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=40.1397&lon=-120.1605&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 3 uninjured
- Status: Completed, report January 25, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 27140
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX91LA135
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/27140/pdf
- Page: https://openairdocs.org/ntsb/LAX91LA135

## Probable cause

THE INADEQUATE PREPARATION OF THE PROPELLER DURING OVERHAUL.  THE INSTALLATION OF AN IMPROPER PITCHED PROPELLER AND THE FATIGUE FAILURE OF THE PROPELLER BLADE EMANATING FROM CORROSION WERE FACTORS IN THE ACCIDENT.

## Sequence of events

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

- Airframe/component/system failure/malfunction, cruise - normal
  - propeller system/accessories,blade - failure,partial (contributing factor)
  - maintenance,rebuild/remanufacture - inadequate, other maintenance personnel (cause)
- Forced landing, descent - emergency

## Analysis

THE AIRCRAFT HAD BEEN IN CRUISE FLIGHT AT AN ALTITUDE OF 7500 FEET MSL FOR TWO AND A HALF HOURS WHEN A BLADE SEPARATED FROM THE FIXED PITCH PROPELLER. THE PILOT SECURED THE ENGINE, STOPPED THE ROTATION OF THE PROPELLER AND LANDED ON A ROAD WITHOUT FURTHER INCIDENT. A POST ACCIDENT ANALYSIS OF THE PROPELLER FAILURE DISCLOSED A FATIGUE CRACK EMANATED FROM A CORROSION AREA ON THE CAMBER SIDE OF THE BLADE.

## Aircraft

- Registration: [N1921Y](https://openairdocs.org/deregistered/N1921Y-2013-02-01), registration cancelled 2013-02-01, S/N 216, built 1964 (OpenAirDocs)
- Reported make and model: MOONEY M20D
- Registry model: [Mooney M20D](https://openairdocs.org/model/mooney-m20d) (registry code 5870210) (OpenAirDocs)
- Registry engine: [Lycoming O&VO-360 series](https://openairdocs.org/engine/lycoming-o-vo-360-series) (registry code 41514, reciprocating) (OpenAirDocs)
- Category: Airplane
- Serial number: 216
- Engines: LYCOMING 0360 180 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Operator: Marlyn R. Taylor
- Registered owner: Marlyn R. Taylor
- Last inspection: Unknown, January 2, 2000
- Departed: 61S, COTTAGE GROVE, OR
- Destination: PO6, BULLHEAD CITY, AZ
- Flight plan: VFR

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 41; commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; flight hours: 1,940 total, 1,000 in this make and model, 1,781 as pilot in command, 39 in the last 90 days, 20 in the last 30 days, 3 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Visibility: 50 statute miles
- Lowest ceiling: none

## 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 19910317006699A](https://openairdocs.org/incident/19910317006699A), Mar 17, 1991: Mooney M20D, Herlong, CA, Substantial damage. Lost a prop blade at cruise. Severe vibration. Landed safely. Fixed pitch prop was wrong pitch. Vibration 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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