Mooney M20F N9708M

Summary

On 5 September 2004 at about 19:32 local time, a Mooney M20F registered N9708M was involved in an accident near Brandon, Mississippi, United States. 3 people were 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

5 September 2004 at 19:32

Classification

Accident

Location

Brandon, Mississippi, United States

Coordinates

32.3572, -90.0131

Aircraft

Mooney M20F

Registration

N9708M

Category

Airplane

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

Atlanta → Shreveport

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

MIA04LA127

Nobody was injured.

A loss of engine power due to the fatigue failure of all studs and/or thru-bolts of the No. 3 cylinder for undetermined reasons causing separation of the cylinder. Contributing to the accident was the unsuitable terrain encountered by the pilot.

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

Read the full NTSB narrative

The pilot stated that he performed a preflight inspection of the airplane and noted the oil capacity was full (8 quarts). Approximately 2 hours into the flight while flying at 10,500 feet, the engine began running rough. He advised air traffic control (ATC), and attempts to correct the rough running engine were unsuccessful. The flight continued and shortly afterwards, the engine developed a severe roughness and he then heard a bang with smoke entering the cockpit. He declared "mayday" with ATC, and requested vectors to the nearest airport. Unable to land there, he executed a forced landing on a nearby highway and collided with a vehicle during the landing roll-out. The No. 3 cylinder was found separated from the crankcase, and all cylinder studs and/or thru-bolts exhibited various forms of fatigue. The No. 3 cylinder connecting rod bolts which were fractured exhibited evidence of either bending or shear overstress. The No. 2 cylinder connecting rod bearing was found welded to the crankpin, and a piece of aluminum lined bearing material was found inside the oil passage of the No. 2 cylinder crankpin journal. Fretting was noted at the No. 3 cylinder contact area, and also at the split-line surface of the right crankcase half at the main bearing locations. The fretting was the greatest at the cylinder contact area between studs Nos. 1 and 2, and also at the split line surface on the right crankcase half at the No. 3 main bearing location. The engine had accumulated 1,390 hours since major overhaul and approximately 873 hours since the No. 3 cylinder was removed and reinstalled.

Quoted verbatim from the NTSB record.