ASN Wikibase Occurrence # 210581
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Date: | Friday 4 May 2018 |
Time: | 19:30 |
Type: | Beechcraft A36 Bonanza |
Owner/operator: | Private |
Registration: | N36LP |
MSN: | E-894 |
Year of manufacture: | 1976 |
Total airframe hrs: | 7951 hours |
Engine model: | Continental IO-520-BB |
Fatalities: | Fatalities: 0 / Occupants: 1 |
Aircraft damage: | Substantial |
Category: | Accident |
Location: | Lafayette County, southeast Shullsburg, WI -
United States of America
|
Phase: | Landing |
Nature: | Private |
Departure airport: | Okmulgee, OK (OKM) |
Destination airport: | Plainfield, WI (WN09) |
Investigating agency: | NTSB |
Confidence Rating: | Accident investigation report completed and information captured |
Narrative:The commercial pilot reported that he heard an unusual noise from the engine during cruise flight and shortly afterward, the engine experienced a total loss of power. The pilot performed a forced landing to an open field.
Visual examination of the engine revealed a hole in the crankcase. A teardown examination revealed fretting on the crankcase mating surfaces, shifting of the No. 2 main bearing within the journal support, thermal damage consistent with a loss of oil lubrication, and separation of the crankshaft. The observed fretting damage was consistent with relative movement of the crankcase halves during operation due to a lack of through-bolt torque. The main journal bearing damage, the separation of the crankshaft, and the crankcase damage were secondary and a result of the loss of lubrication.
An engine overhaul was completed in about 11 years 5 months before the accident; about 849 flight hours had accumulated since the overhaul. Two cylinders were replaced 6 years before the accident, and one cylinder was replaced during the most recent annual inspection about 9 months before the accident. It is likely that improper torque of the through-bolt nuts was applied during one of the cylinder replacement events, though it could not be determined which event.
Probable Cause: A catastrophic engine failure due to improper torque on the engine through-bolt nuts, which resulted in relative movement between the crankcase halves, damage to a main journal bearing, and a loss of oil lubrication.
Accident investigation:
|
| |
Investigating agency: | NTSB |
Report number: | CEN18LA159 |
Status: | Investigation completed |
Duration: | 1 year |
Download report: | Final report |
|
Sources:
NTSB
FAA register:
http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=36LP https://flightaware.com/live/flight/N36LP Location
Revision history:
Date/time | Contributor | Updates |
07-May-2018 13:52 |
Geno |
Added |
07-May-2018 13:54 |
Geno |
Updated [Date] |
01-Jun-2019 07:28 |
ASN Update Bot |
Updated [Aircraft type, Operator, Nature, Departure airport, Destination airport, Source, Damage, Narrative, Accident report, ] |
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