ASN Wikibase Occurrence # 170536
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| Date: | Saturday 18 October 2014 |
| Time: | 18:30 |
| Type: |  Lancair Legacy |
| Owner/operator: | private |
| Registration: | N550AC |
| MSN: | L2K-315 |
| Year of manufacture: | 2008 |
| Total airframe hrs: | 646 hours |
| Engine model: | Continental IO-550-N |
| Fatalities: | Fatalities: 0 / Occupants: 1 |
| Aircraft damage: | Destroyed |
| Category: | Accident |
| Location: | Jasper County Airport-Bell Field (KJAS), Jasper, Texas -
 United States of America
|
| Phase: | Initial climb |
| Nature: | Private |
| Departure airport: | Jasper, TX (JAS) |
| Buchanan Dam, TX | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
The pilot reported that he was returning from an air race competition and that, about 15 minutes into the flight, he heard a “thump” and thought the airplane had struck a bird. The pilot then heard a second “thump” along with a “rattle and vibration,” so he found a place to make a forced landing. While preparing to land, he heard an “explosion” and then saw flames by his left foot and black smoke fill the cockpit. The pilot made a forced landing to a field and exited the airplane before it was destroyed by fire.
Postaccident examination of the engine revealed that the No. 3 cylinder’s exhaust rocker cover was present but that it was only installed on the cylinder by one screw. The other four screws were missing. The No. 3 cylinder’s intake rocker cover and aft rocker arm bolt were missing. The forward rocker arm bolt was installed but loose, and visible rubbing was observed on the boss where the missing bolt was supposed to be installed. According to the engine manufacturer, if a rocker cover is not installed, the engine will port out most of its oil is several minutes. Therefore, the missing rocker cover likely resulted in the engine losing a significant amount of oil during the flight, which led to a catastrophic and uncontained engine failure. It is also likely that, when the crankcase was breached, the fuel lines and the electronic fuel transducer were compromised, which resulted in the subsequent in-flight fire. The No. 3 cylinder intake rocker cover was not located at the accident site, and the pilot reported that he did not know why the rocker cover and aft rocker arm bolt were not installed or why the exhaust rocker cover was only partially installed. He said that the engine performed great during the air race and that he did not perform engine maintenance after the race.
Probable Cause: A catastrophic and uncontained engine failure due to oil starvation. Contributing to the accident was the missing No. 3 cylinder intake rocker cover for reasons that could not be determined based on the available evidence.
Accident investigation:
 |
|
Sources:
NTSB
FAA register: http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=550AC
https://flightaware.com/photos/view/221656-943d37322549cebbc2ed95219bc4d66c130ca2fc
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 20-Oct-2014 06:22 | Geno | Added |
| 21-Dec-2016 19:28 | ASN Update Bot | Updated [Time, Damage, Category, Investigating agency] |
| 30-Nov-2017 19:27 | ASN Update Bot | Updated [Operator, Other fatalities, Departure airport, Destination airport, Source, Narrative] |
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