Forced Landing and Aircraft Rollover Due to Engine Misfire

Casualties unknown • Iola, WI, US

A pilot executed a forced landing in a field after experiencing partial power loss shortly after takeoff. The aircraft flipped over upon touchdown, resulting from lead fouled spark plugs that caused consistent engine failure despite pre-flight checks.

What happened

Shortly after departing the airport, the pilot encountered a significant reduction in engine power while climbing to approximately 100 feet above ground level. This mechanical failure left insufficient altitude for continued flight, necessitating an immediate forced landing in a nearby agricultural area. The terrain consisted of soft, wet soil typical of a potato field.

Before reaching the ground, the pilot attempted standard emergency procedures by switching fuel tanks and magnetos to rule out simple operational errors or fuel contamination. However, the power loss remained constant regardless of these adjustments. Upon impact with the uneven ground, the aircraft's momentum caused it to flip over onto its back.

The investigation

Post-accident inspection of the engine revealed a critical maintenance issue. An examination of the ignition system showed that five of the eight spark plugs were heavily lead fouled. Three of these plugs were completely shorted out, preventing any spark generation, while two others sparked intermittently. Notably, two of the malfunctioning plugs were located on the same cylinder, which would have severely compromised combustion efficiency in that specific engine section.

The pilot reported that the pre-takeoff engine run-up and magneto check appeared normal, suggesting the fouling may have developed rapidly or was not fully apparent during the brief ground check.

Probable cause

Engine power loss due to lead fouled spark plugs, which resulted in a forced landing and subsequent aircraft rollover.

Frequently asked questions

What happened in the 1985-07-13 Piper PA-22 accident near Iola, WI?

A pilot executed a forced landing in a field after experiencing partial power loss shortly after takeoff. The aircraft flipped over upon touchdown, resulting from lead fouled spark plugs that caused consistent engine failure despite pre-flight checks.

What aircraft was involved and where did it happen?

The accident on 1985-07-13 involved a Piper PA-22, registration N1487A, at Iola, WI.

What was the probable cause of the accident?

Engine power loss due to lead fouled spark plugs, which resulted in a forced landing and subsequent aircraft rollover.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001214X37051. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.

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