- Date
- June 21, 2015, 11:30 local (16:30 UTC)
- Place
- Sheboygan, WI
- Injuries
- 1 uninjured
- Damage
- Substantial damage
- Phase of flight
- Initial climb
- Aircraft
- N1168ZMooney M20K
- Defining event
- Initial climb: Loss of engine power (total)
- Weather
- Instrument (IMC) · Day
- Status
- Completed · report September 24, 2015
- Report
- Approved by Office Director
- NTSB office
- Central Region
- Parties
- FAA Flight Standards District Office
- FAA report
- 20150621009569A
- Case key
- 91414
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
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.
Findings · 2
NTSB’s coded findings. Those marked are part of the probable cause; the rest are factors or other findings. Under each, the cases with the same finding.
Sequence of events
The events NTSB coded, in order, by phase of flight. The defining event is the one that best describes the accident. Under each, the cases with the same event anywhere in their sequence.
Analysis
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.
Factual narrative
On June 21, 2015, about 1130 central daylight time, the pilot of a Mooney M20K, N1168Z, made a forced landing in a wheat field 5 miles south of Sheboygan (KSBM), Wisconsin. The pilot, the sole occupant on board, was not injured. The airplane was substantially damaged. The airplane was registered to and operated by the pilot under the provisions of Title 14 Code of Federal Regulations Part 91 as a personal flight. Instrument meteorological conditions prevailed, and an instrument flight rules flight plan had been filed and activated. The flight originated from KSBM at 1113 and was destined for Elkhart (KEKM), Indiana.Shortly after airplane departed, the pilot advised he was returning to KSBM due to low oil pressure. The airplane lost engine power and the pilot made a forced landing in a wheat field five miles south of the airport. A Federal Aviation Administration (FAA) airworthiness inspector who examined the airplane reported finding no oil in the crankcase. He reported the rear bulkhead was wrinkled and the empennage was twisted. On July 1, 2015, an FAA airworthiness inspector examined the engine and turbocharger. He reported the turbocharger was dry and did not appear to be at fault. On August 17, the FAA airworthiness inspector examined the engine again at a teardown facility in Poplar Grove, Wisconsin. He reported finding evidence of pre-ignition in the number 5 cylinder that appeared to have been caused by failed spark plugs. The top and sides of the piston head were eroded, allowing exhaust gases to pressurize the crankcase and force engine oil out of the breather tube.
Aircraft
- Registration
- N1168Z
- Reported as
- Mooney M20K
- Category
- Airplane
- Serial number
- 25-0697
- Built
- 1982
- Engine
- Continental TSIO-520-MB, 210 horsepower, reciprocating
- Damage
- Substantial damage
- Flight
- Personal · Part 91
- Operator
- James R. Pawlak
- Registered owner
- James R. Pawlak
- Airworthiness certificate
- Standard, Normal
- Departed
- KSBM · Sheboygan, WI
- Destination
- KEKM · Elkhart, IN
- Flight plan
- IFR
- Airport
- KSBM · Sheboygan County Mem
- Equipment
- Handheld GPS, Data recorder, Auto-pilot, Stall warning system
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
- 64
- Injuries
- None
- Certificate
- Private
- Airplane ratings
- Single-engine land, Multi-engine land
- Instrument ratings
- Airplane
- Medical
- Class 3, With waivers/limitations
- Seat
- Left
- Restraint
- 3-point
- Flight hours
- 3,570 total · 3,270 in this make and model · 3,570 as pilot in command
Weather
- Conditions
- Instrument (IMC) · Day
- Wind
- 150° at 5 knots
- Visibility
- 1.75 statute miles
- Lowest ceiling
- 3,100 ft broken
- Temperature
- 70 °F, dew point 66 °F
- Altimeter
- 29.81 inHg
- Observed at
- KSBM, 5 nm away
Docket · 11
The files NTSB released with the investigation on September 2, 2015, on NTSB’s docket system: statements, records, photos and specialists’ reports. 8.2 MB in all.
FAA reports on this event · 1
The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.