Beechcraft 35 N460B

Summary

On 9 April 2007 at about 18:30 local time, a Beechcraft 35 registered N460B was involved in an accident near Topeka, Kansas, United States. 2 people were on board and one had minor injuries. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

9 April 2007 at 18:30

Classification

Accident

Location

Topeka, Kansas, United States

Nearest airport

Philip Billard Muni (TOP)

Coordinates

38.9517, -95.6633

Aircraft

Beechcraft 35

Registration

N460B

Category

Airplane

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

Topeka → Kansas City

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

DEN07LA083

1 person had minor injuries.

The use of unapproved bolts to mount the crankshaft and gear together, causing fatigue and failure of those mounting bolts, resulting in the subsequent loss of engine power. Factors contributing to the accident were the separation of the crankshaft gear, and the lack of suitable terrain for a forced landing.

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

Read the full NTSB narrative

According to the pilot, shortly after departing runway 18 she heard what "sounded like a loud backfire, a single bang," and then the engine lost power. The pilot selected a nearby field and performed a forced landing. During the landing the nose gear collapsed resulting in substantial damage. An examination of the engine revealed that the crankshaft gear separated from the crankshaft and was loose inside the accessory case. The upper portions of five of the six screws used to secure the gear to the crankshaft were found in the accessory case. Metallurgical examination of the fracture surface revealed signatures consistent with fatigue fractures. One screw was sectioned and tested for hardness with the results of 29, 30, 30, and 31 Rockwell C Harness (HRC). According to TCM, the drawing specifies an H5 fastener with a hardness requirement of 32 through 37 HRC. In addition, the head of the screw had a diameter of .40 inches or less. The TCM drawing specifies a diameter of .44 inches. According to TCM, this could have resulted in inadequate torque for this installation. An examination of the airplane flight controls and engine controls revealed no anomalies.

Quoted verbatim from the NTSB record.