# NTSB SEA96LA183: Cessna 172N, N738PM, Enumclaw, WA, August 9, 1996

- Type: NTSB accident investigation
- Classification: Accident · Minor injuries · Limited investigation · Final report
- Date: August 9, 1996, 16:00 local (23:00 UTC)
- Place: Enumclaw, WA
- Coordinates: 47.099098, -121.599754 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=47.0991&lon=-121.5998&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: Minor injuries
- Injuries: 1 minor, 1 uninjured
- Status: Completed, report February 28, 1997
- Report: Approved by Office Director
- NTSB case key (mKey): 42440
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA96LA183
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/42440/pdf
- Page: https://openairdocs.org/ntsb/SEA96LA183

## Probable cause

failure of the engine magneto drive, which resulted in a loss of engine power.  The lack of suitable terrain for a forced landing was a related factor.

## Sequence of events

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

- Loss of engine power, cruise
  - ignition system,magneto - failure,total (cause)
- Forced landing, emergency descent/landing
- On ground/water encounter with terrain/water, emergency landing
  - terrain condition - none suitable (contributing factor)

## Analysis

During an aerial observation flight, the engine progressively lost power. The pilot made a forced landing on uneven terrain, where the airplane flipped over. Inspection of the engine revealed a failed cam follower in the magneto drive.

## Factual narrative

On August 9, 1996, approximately 1600 Pacific daylight time, a Cessna 172N, N738PM, sustained substantial damage when it flipped over during an emergency landing near Enumclaw, WA.  The commercial pilot was uninjured.  The pilot rated passenger received minor injuries.  The flight was conducted under 14 CFR 91 in visual meteorological conditions.  No flight plan was filed for the flight which had originated at Boeing Field, Seattle, Washington, approximately 1345 hours.

The flight was an aerial observation flight.  The pilot reported that he was in a 300 ft/minute descent when the engine made a strange noise and began to vibrate out of the ordinary.  The RPM dropped to 1900 and stayed there for about 20-30 seconds.  The power then dropped to 1500 RPM.  The pilot established a glide speed and turned toward the Howard Hanson Reseviour.  When the RPM dropped to 1000, the pilot made a forced landing.  During the landing in grass and uneven terrain, the airplane flipped over.

Inspection of the engine by FAA inspectors revealed that the cam follower in the magneto drive had failed due to a lack of lubrication.

## Aircraft

- Registration: [N738PM](https://openairdocs.org/aircraft/N738PM), registered now, S/N 17270131, built 1977 (OpenAirDocs)
- Reported make and model: Cessna 172N
- Registry model: [Cessna 172N](https://openairdocs.org/model/cessna-172n) (registry code 2072434) (OpenAirDocs)
- Registry engine: [Lycoming 0-320 series](https://openairdocs.org/engine/lycoming-0-320-series) (registry code 41508, reciprocating) (OpenAirDocs)
- Category: Airplane
- Serial number: C172-70131
- Airframe hours: 6456
- Engines: Lycoming O-320-H2AD 160 horsepower reciprocating
- Damage: Substantial damage
- Flight: Aerial observation, Part 91
- Operator: Aeroflight
- Registered owner: Terry Jean Houston
- Airworthiness certificate: Standard, Utility
- Last inspection: 100 hour, July 10, 1996, 101 hours before
- Departed: BFI, SEATTLE, WA

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 24; flight instructor, commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; seat: right; flight hours: 513 total, 113 in this make and model, 447 as pilot in command, 100 in the last 90 days, 35 in the last 30 days, 2 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 225° at 5 knots
- Visibility: 30 statute miles
- Lowest ceiling: none
- Temperature: 81 °F, dew point 50 °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 19960809045279A](https://openairdocs.org/incident/19960809045279A), Aug 9, 1996: Cessna 172N, Enumclaw, WA, Substantial damage. Aerial observation flight. Engine vibration gradual power loss. Landed tall grass. Flipped. Mag cam drive failed.

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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