Beechcraft B24R N6951R

Summary

On 9 May 2000 at about 21:40 local time, a Beechcraft B24R registered N6951R was involved in an accident near Anchorage, Alaska, United States. 2 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

9 May 2000 at 21:40

Classification

Accident

Location

Anchorage, Alaska, United States

Nearest airport

Merrill Field (MRI)

Coordinates

61.2208, -149.8502

Aircraft

Beechcraft B24R

Registration

N6951R

Category

Airplane

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Instructional

Phase of flight

Not recorded

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

ANC00FA056

Nobody was injured.

A fatigue failure of the crankcase through bolt, the separation of number 3 cylinder assembly, and the inadequate maintenance/service of the airplane by company maintenance personnel.

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

Read the full NTSB narrative

The first pilot, a certificated flight instructor, was providing flight instruction to the second pilot, a certificated private pilot. While returning to the airport, during the initial descent, the engine began to run rough, and lose power. The roughness improved momentarily, followed by a severe engine vibration, a loud bang, and complete loss of engine power. During a forced landing in a densely populated neighborhood, the airplane struck a power line, veered to the right, collided with the street, and came to rest in the front yard of a daycare center. Examination of the engine revealed the number 3 cylinder was broken free at the crankcase-mounting flange. A metallurgical examination of the number 4 position crankcase thru-bolt showed signs of fatigue cracking that emanated from the thread root. In addition, the cylinder flange mating surface displayed signs of fretting damage consistent with relative movement between the cylinder and the crankcase. The operator's director of maintenance stated that about 40 hours before the accident, he repaired a substantial oil leak between the number 3 cylinder, and the engine crankcase. He said that in the process of the repair he removed the number 4 position crankcase thru-bolt nut, applied an engine sealant, reinstalled the through bolt nut, and torqued the nut in accordance with the Lycoming overhaul manual. There was no engine log book entry pertaining to the engine total time, aircraft total time, or date when this repair was accomplished.

Quoted verbatim from the NTSB record.