# NTSB ATL91LA157: Piper PA-25-235, N7658Z, Roxobel, NC, August 13, 1991

- Type: NTSB accident investigation
- Classification: Accident · Minor injuries · Limited investigation · Final report
- Date: August 13, 1991, 13:00 local (17:00 UTC)
- Place: Roxobel, NC
- Coordinates: 36.199386, -77.230003 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=36.1994&lon=-77.2300&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: Minor injuries
- Injuries: 1 minor
- Status: Completed, report December 4, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 8455
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ATL91LA157
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/8455/pdf
- Page: https://openairdocs.org/ntsb/ATL91LA157

## Probable cause

THE FAILURE OF THE LEFT MAGNETO STOP PIN, RESULTING IN THE SEIZURE OF THE MAGNETO AND THE FAILURE OF THE MAGNETO DRIVE GEAR, AND ULTIMATELY ENGINE STOPPAGE.  A FACTOR IN THIS ACCIDENT WAS: THE PRESENCE OF TREES AT THE FORCED LANDING AREA.

## 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, maneuvering - aerial application
  - ignition system,magneto - movement restricted (cause)
  - accessory drive assy,drive gear - sheared (cause)
- Forced landing, descent - emergency
- In flight collision with object, descent - emergency
  - object - tree(s) (contributing factor)
- In flight collision with terrain/water, descent - uncontrolled

## Analysis

THE AG PILOT WAS SETTING UP FOR AERIAL APPLICATION PASS WHEN THE ENGINE QUIT SUDDENLY.  UNABLE TO GLIDE TO A CLEARED AREA, HE FORCE LANDED IN A WOODED AREA.  THE ENGINE WAS EXAMINED FOLLOWING THE ACCIDENT.  THE INVESTIGATION REVEALED THAT AN IMPULSE COUPLING STOP PIN FROM THE LEFT MAGNETO HAD FAILED.  THE MAGNETO SUBSEQUENTLY JAMMED, AND THE TEETH OF THE MAGNETO DRIVE GEAR IN THE ENGINE WERE SHEARED OFF.  THIS RENDERED BOTH MAGNETOS INOPERATIVE, RESULTING IN THE ENGINE STOPPAGE.

## Aircraft

- Registration: [N7658Z](https://openairdocs.org/deregistered/N7658Z-2004-01-30), registration cancelled 2004-01-30, S/N 25-3800, built 1966 (OpenAirDocs)
- Reported make and model: PIPER PA-25-235
- Registry model: [Piper PA-25-235](https://openairdocs.org/model/piper-pa-25-235) (registry code 7102504) (OpenAirDocs)
- Registry engine: [Lycoming 0-540 series](https://openairdocs.org/engine/lycoming-0-540-series) (registry code 41532, reciprocating) (OpenAirDocs)
- Category: Airplane
- Serial number: 25-3800
- Airframe hours: 5349
- Engines: LYCOMING O-540-B2B5 235 horsepower reciprocating
- Damage: Substantial damage
- Flight: Aerial application, Part 137
- Operator: Newsome, John S & Katherine A
- Registered owner: Newsome, John S & Katherine A
- Airworthiness certificate: Special, Restricted (Special)
- Last inspection: Annual, September 1, 1990, 153 hours before
- Departed: ASJ, AHOSKIE, NC

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 39; commercial; airplane ratings: single-engine land; medical: class 2, valid medical--no waivers/lim.; seat: center; flight hours: 2,200 total, 2,000 in this make and model, 2,017 as pilot in command, 105 in the last 90 days, 50 in the last 30 days

## Weather

- Conditions: Visual (VMC), Day
- Wind: 320° at 7 knots
- Visibility: 6 statute miles
- Temperature: 72 °F, dew point 61 °F
- Altimeter: 30.00 inHg
- Observed at: RWI, 38 nm away

## 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 19910813033739A](https://openairdocs.org/incident/19910813033739A), Aug 13, 1991: Piper PA25235, Roxobel, NC, Substantial damage. Engine quit. Struck trees. Magneto impulse coupling stop pin failed. Mag rotated hit,other pin. Mag drive sheared.

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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