Pilot Debrief

Sorrell Aircraft Skybolt near Williamstown, KY — 2008-09-21

Final reportNYC08LA317
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Date
2008-09-21
Location
Williamstown, KY, USA
Aircraft
Sorrell Aircraft Skybolt
Registration
N3EG
Category
Airplane
Highest injury
Serious
Fatalities
0
Phase of flight
Cruise

Probable cause

A loss of engine power due to oil starvation as a result of improper servicing (removal of preserving fluid) of the engine after it had been returned from storage.

NTSB narrative

While in cruise flight at 2,000 feet the engine suddenly stopped producing power. The pilot and passenger, wearing parachutes, elected to parachute to the ground. Eyewitnesses reported seeing the pilot leave the airplane approximately 10 to 15 seconds after the passenger departed and after placing the airplane in a nose dive. The airplane impacted a rectangular farm field and the pilot and passenger suffered serious injuries due to the low altitude in which they parachuted from. The airplane had been purchased by the accident pilot approximately one month prior to the accident. According to the airplane's engine maintenance log, on April 28, 2004, the engine had undergone a preservation process called "pickling." The process utilized 10 quarts of pickling oil and the engine was placed in storage. On May 9, 2006 the engine was drained of the pickling oil and replaced with 7 quarts of 50 WT oil. The cylinders were drained and cleaned, and then the engine was test ran. The NTSB Materials laboratory examined components of the engine and analyzed an unknown substance within the lubricating journals of the camshaft and crankshaft. The compounds of the unknown substance was those found in corrosion preservation fluids also known as pickling fluids and are not found in lubricating oil. The presence of these compounds indicates that it was likely that some pickling fluids were still in the engine at the time of the accident; however, a specific pickling fluid could not be determined. According to the engine manufacturer, pickling fluid has been known to clog lubrication channels by forming a tarry residue when present in engines for prolonged periods and result in oil starvation. The number 2 main bearing and piston were thermally damaged and that thermal damage is consistent with oil starvation. Therefore it is possible that the residual pickling fluid clogged the lubrication channels for the number 2 position resulting in oil starvation.

Analysis

Primary failure mode
Engine power loss
First missed decision gate
Pilot could have conducted a precautionary landing after engine failure.

NTSB coding

Evidence available

  • Photos
  • 8 docket documents
View NTSB final reportView NTSB docket

Docket documents8

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