Mooney M20F N6442Q

Summary

On 12 January 2003 at about 23:47 local time, a Mooney M20F registered N6442Q was involved in an accident near Tacoma, Washington, United States. One person was on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

12 January 2003 at 23:47

Classification

Accident

Location

Tacoma, Washington, United States

Nearest airport

Tacoma Narrows (TIW)

Coordinates

47.2764, -122.5769

Aircraft

Mooney M20F

Registration

N6442Q

Category

Airplane

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

Puyallup → Olympia

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

SEA03FA025

Nobody was injured.

A loss of engine power during cruise flight due to fatigue failure of the crankshaft as a result of an inadequate quality of material during the manufacturing process. Trees were a factor.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

The pilot reported that while en route, the engine backfired, followed by a total loss of power. The pilot initiated a forced landing, attempting to land at a nearby airport. The aircraft was unable to reach the runway and collided with trees and brush about 200 yards short of the runway. During a post-accident engine examination, the crankshaft was found fractured through the forward side of the number four journal. Metallurgical examination of the fracture surface revealed that the crankshaft failure was the result of fatigue initiating at a subsurface inclusion. Scanning electron microscopic examinations established that the fatigue initiated at a single subsurface site located 0.023 inch below the journal surface. Closer inspection found an approximate 0.002 to 0.003 inch diameter pit at the origin location. The pit was mostly empty but contained remnants of material that was identified by energy dispersive x-ray spectroscopic as mostly aluminum and calcium. The age of the crankshaft could not be determined but appeared to be an older crankshaft that was manufactured prior to the manufacturers transition to vacuum arc remelted steels which have higher fatigue strengths and which almost eliminates the presence of inclusions.

Quoted verbatim from the NTSB record.