Probable cause
A loss of engine performance due to lead fouling of the lower spark plugs, which resulted in an off airport forced landing.
NTSB analysis
The pilot departed an airport at an elevation about 5,800 ft mean sea level (msl), and reported that, upon reaching about 6,700 ft msl, the airplane would not continue to climb. The pilot performed a forced landing to a field, during which the right wing impacted a fence post, resulting in substantial damage.
Examination of the engine revealed that all lower spark plugs were severely lead fouled. According to the manufacturer, severely lead fouled spark plugs can lead to misfiring, resulting in a degradation of engine performance. It is likely that the fouled spark plugs resulted in a loss of engine performance and the airplane’s subsequent inability to maintain altitude.
Text from the NTSB. Open the NTSB docket for WPR21LA316 for the full record.
Event
- Date
- Aug 12, 2021
- Type
- Accident
- Place
- Stanley, New Mexico
- Nearest airport
- Double Eagle II (AEG)
- Highest injury
- None
- Weather
- Visual (VMC)
- Light
- Day
Beech 77
- N-number
- N3873Y
- Category
- Airplane
- Year built
- 1981
- Damage
- Substantial
- Operating rule
- Part 91 (general aviation)
- Purpose of flight
- Personal
From the NTSB aviation accident database: N-registered aircraft, events since 2008, data through Oct 28, 2026. The file is published monthly, so the latest weeks are incomplete and recent records can change. The official source is the NTSB aviation investigation search. CheckAero is independent and not affiliated with the NTSB.