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ASN Wikibase Occurrence # 175851
Last updated: 1 October 2020
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Date:21-MAR-2004
Time:12:43
Type:Silhouette image of generic GLAS model; specific model in this crash may look slightly different
Stoddard-Hamilton Glasair II
Owner/operator:Private
Registration: N309TS
C/n / msn: 309
Fatalities:Fatalities: 0 / Occupants: 1
Other fatalities:0
Aircraft damage: Substantial
Category:Accident
Location:Obispo, CA -   United States of America
Phase: Landing
Nature:Private
Departure airport:Corcoran, CA (CRO)
Destination airport:San Luis Obispo, CA (SBP)
Investigating agency: NTSB
Narrative:
The airplane experienced a loss of engine power and impacted a ditch during the pilot's forced landing in a field. While approaching the proximity of the destination airport, the pilot observed the engine gauges indicating rising oil temperature. About 5 miles from the airport, the engine emitted a loud noise and he declared an emergency due to an engine failure. Realizing that he would be unable to make it to the runway, the pilot executed a forced landing in a field; during the landing roll, the airplane impacted a ditch and tumbled. Post-accident external visual examination by a Federal Aviation Administration (FAA) inspector revealed that the engine sustained a catastrophic failure, with a hole knocked in the upper case spine above the rear cylinders. Looking through the hole, the inspector observed that the right rear piston had seized in the No. 3 cylinder and its respective connecting rod was broken just above crankshaft rod end flare. The inspector could not identify the rod end cap or the bearing shells. The No. 3 piston skirt was visibly scorched in the direction of piston travel. A visual examination of the engine, disclosed that all of the cylinders were worn and scored. After the accident, the owner took the engine to a maintenance facility that examined the engine and reported that rod bearing in the No. 3 cylinder failed. The facility declined to provide detailed observations on the internal condition of the engine, the rod fracture, and condition of the bearing. The FAA inspector said the pilot told him that prior to the accident, the engine was experiencing excessive oil consumption. In response, the pilot removed the No. 3 cylinder from the engine and employed an engine shop to change the piston in an effort to alleviate the excessive oil consumption problems. After the maintenance was preformed, the pilot reinstalled the cylinder. The inspector added that sometime prior to the accident the pilot had also modified the engine by installing larger pistons.
Probable Cause: The loss of engine power due to the failure of the #3 cylinder piston and connecting rod for undetermined reasons.

Sources:

NTSB: https://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20040330X00397&key=1


Revision history:

Date/timeContributorUpdates
02-May-2015 13:46 Noro Added
21-Dec-2016 19:30 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
07-Dec-2017 17:47 ASN Update Bot Updated [Other fatalities, Departure airport, Destination airport, Source, Narrative]

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