Pilot Debrief

MOONEY M20K near Sheboygan, WI — 2015-06-21

Final reportCEN15LA279
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Date
2015-06-21
Location
Sheboygan, WI, USA
Airport
KSBM
Aircraft
MOONEY M20K
Registration
N1168Z
Category
Airplane
Highest injury
None
Fatalities
0
Phase of flight
Climb

Probable cause

Oil starvation due to preignition in the No. 5 cylinder as a result of failed spark plugs; the top and sides of the piston head were eroded, which allowed the exhaust gases caused by the preignition to pressurize the crankcase and force engine oil out of the breather tube.

NTSB narrative

Shortly after takeoff, the pilot advised air traffic control that he was returning to the airport due to low oil pressure. The engine subsequently lost power, and the pilot was forced to land in a wheat field 5 miles south of the airport. During on-site examination of the airplane, no oil was found in the crankcase, and subsequent examination of the engine and turbocharger revealed that the turbocharger was dry. Further examination of the engine revealed evidence of preignition in the No. 5 cylinder that appeared to have been caused by failed spark plugs. The top and sides of the piston head were eroded, which allowed the exhaust gases caused by the preignition to pressurize the crankcase and force engine oil out of the breather tube.

Analysis

Primary failure mode
Engine power loss
First missed decision gate
Pilot could have returned to KSBM before engine power loss became critical.

NTSB coding

Evidence available

  • Photos
  • 11 docket documents
View NTSB final reportView NTSB docket

Docket documents11

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