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NTSB Report

October 4, 2016 · Cessna 172K · N46377

Wilmot, WI

Overview

Report Status
Final with probable cause
Event Type
Accident
Date
October 4, 2016
Injury Outcomes
No injuries (1 uninjured)
Location
Wilmot, WI
Aircraft
Cessna 172K (1968)
Tail Number
N46377
Injuries
None
Aircraft Damage
Substantial
NTSB Number
CEN17LA006

The private pilot stated that the engine experienced a partial loss of power shortly after takeoff on the local flight. In an effort to regain power, the pilot switched fuel tanks, applied carburetor heat, and richened the fuel mixture, but the engine continued to operate at reduced power. The pilot attempted to land at a nearby airport; however, he overshot the runway and decided to perform a forced landing to an adjacent cornfield. During the landing, the right wing impacted the corn, and the airplane came to rest upright. Partial disassembly of the engine revealed a failure of the No. 1 piston pin plug due to corrosion in the No. 1 cylinder barrel. The plug failure resulted in significant oil contamination and subsequent oil starvation and damage to the crankshaft connecting rod bearings. The damage to the bearings resulted in the partial loss of engine power.

NTSB Probable Cause

A failure of the No. 1 piston pin plug due to corrosion in the cylinder barrel, which resulted in oil contamination, oil starvation to the crankshaft connecting rod bearings, and a subsequent partial loss of engine power.

Full Narrative

On October 4, 2016, at 1511 central daylight time, a Cessna 172K single-engine airplane, N46377, impacted a cornfield during a forced landing following a partial loss of engine power while maneuvering near Wilmot, Wisconsin. The private pilot, who was the sole occupant, was not injured, and the airplane sustained substantial damage to the right wing. The airplane was registered to 696 Corp, Grayslake, Illinois, and operated by a private individual as a Code of Federal Regulations Part 91 personal flight. Visual meteorological conditions prevailed at the time of the accident and a flight plan was not filed. The flight departed the Burlington Municipal Airport (BUU), Burlington, Wisconsin, about 1445. According to the pilot, while maneuvering after takeoff from BUU, the engine began to lose power. The pilot then switched fuel tanks, applied carburetor heat, full rich mixture, but the engine remained at reduced power. The pilot attempted to land at Westosha Airport, Wilmot, Wisconsin, however, he overshot the runway. The pilot then decided to execute a forced landing to an adjacent cornfield. During the forced landing, the right wing impacted the corn, and the airplane came to rest upright. The accident engine was a 150-horsepower, four cylinder, Lycoming O-320-E2D engine, serial number L-22806-27A. It was examined at the facilities of Myers Aviation, Oshkosh, Wisconsin, under the supervision of the National Transportation Safety Board (NTSB) investigator and inspectors from the Federal Aviation Administration (FAA). Visual examination of engine exterior and components revealed no anomalies that would have precluded normal operation. The engine oil filter was removed and disassembled. The internal filter displayed heavy deposits of metal material. Due to the metal deposits in the oil filter, the engine was disassembled. Partial disassembly of the engine revealed the number 1 cylinder piston pin plug was destroyed and metal debris was noted in the engine oil and engine oil filter. The engine crankshaft and connecting rods displayed discoloration and heat signatures consistent with oil starvation. The number 3 and 4 connecting rod bearings were extruded and melted from the rod journals. The cylinder bores displayed corrosion and discoloration on their respective inner surfaces. According to the engine records, the engine underwent its most recent annual inspection on October 1, 2015, at a total time of 3,160 hours, and 1,176 hours since major overhaul. At the time of the accident, the engine had accumulated 34 hours since its inspection.

Flight

Event TypeAccident
Event Time15:11 CDT
Nearest Airport0nm
Flight Plan FiledNone
Aircraft FireNo
Aircraft ExplosionNo

Aircraft

AircraftCessna 172K
Tail NumberN46377
Aircraft CategoryAir
DamageSubstantial
Operating RulePart 91
Engines1
Engine TypeReciprocating
Engine DetailsLycoming · O-320-E2D · Reciprocating · 150
Seats4

People & Injuries

Injury SummaryNo injuries (1 uninjured)
Fatal0
Serious0
Minor0
Uninjured1
Total1
Crew 1Age 72 · Third Class · None

Conditions

ConditionsVMC
LightDaylight
Wind140° @ 6 kt, gusting 14 kt
Visibility10 sm
CeilingNone
Temperature / Dew Point70 F / 52
Altimeter30.02 inHg
Observation Time20:15
Weather SourceWFAC

Appendix: Source Data