- Date
- September 6, 1992, 09:00 local (15:00 UTC)
- Place
- Cokeville, WY
- Injuries
- 2 uninjured
- Damage
- Substantial damage
- Phase of flight
- Maneuvering
- Aircraft
- N78599Piper PA-12
- Weather
- Visual (VMC) · Day
- Status
- Completed · report September 14, 1993
- Report
- Approved by Office Director
- FAA report
- 19920906035469A
- Case key
- 42893
From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.
On this page
Probable cause
Fatigue failure of the crankshaft. Factors include non suitable terrain for a forced landing and an improper propeller.
Sequence of events
NTSB’s coding before 2008: each occurrence and phase of flight, and the causes and factors under it. The codes are defined in NTSB’s coding manual.
Analysis
The pilot of the Piper pa 12 realized that he was experiencing a power loss while maneuvering, looking for missing sheep. He turned to lower, flatter terrain. The engine continued to lose power, so he made a forced landing in unsuitable terrain. The aircraft nosed over after touching down. Metallurgical testing revealed that the crankshaft had experienced fatigue failure. The engine had been installed on a field approval. The propeller/engine combination installed in this aircraft had not been tested or approved for this, or any other, installation.
Aircraft
- Registration
- N78599
- Reported as
- Piper PA-12
- Category
- Airplane
- Serial number
- 12-3961
- Airframe hours
- 4,777
- Engine
- Lycoming O-340-A1A, 170 horsepower, reciprocating
- Damage
- Substantial damage
- Flight
- Personal · Part 91
- Operator
- John I Ritter
- Registered owner
- John I Ritter
- Airworthiness certificate
- Special, Restricted (Special)
- Last inspection
- Annual · May 16, 1992 · 68 hours before
- Departed
- Kemmerer, WY
Matched to the registry by N-number and the event date; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.
Flight crew
As NTSB recorded them. NTSB leaves out names.
- Role
- Pilot
- Age
- 51
- Certificate
- Private
- Airplane ratings
- Single-engine sea, Single-engine land
- Medical
- Class 2, Valid Medical--no waivers/lim.
- Seat
- Front
- Flight hours
- 861 total · 824 in this make and model · 821 as pilot in command · 70 in the last 90 days · 29 in the last 30 days · 2 in the last 24 hours
Weather
- Conditions
- Visual (VMC) · Day
- Wind
- Calm
- Visibility
- 40 statute miles
- Lowest ceiling
- None
- Temperature
- 50 °F, dew point -0 °F
FAA reports on this event · 1
The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.