Beechcraft A36 N16JR

Summary

On 13 March 2006 at about 17:43 local time, a Beechcraft A36 registered N16JR, operated by Peter Tomarken, was involved in an accident near Santa Monica, California, United States. 2 people were on board and 2 died. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

13 March 2006 at 17:43

Classification

Accident

Location

Santa Monica, California, United States

Coordinates

34.0036, -118.4939

Aircraft

Beechcraft A36

Registration

N16JR

Category

Airplane

Engines

1

Operator

Peter Tomarken

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

Santa Monica → San Diego

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

LAX06FA129

2 people died.

The failure of an aviation maintenance technician to properly torque and cotter pin the number 2 connecting rod bolts at their attach point to the crankshaft, which resulted in the separation of the connecting rod in flight, and complete power loss.

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

Read the full NTSB narrative

The engine lost power during the takeoff-initial climb and the pilot ditched the airplane in the ocean. Examination showed that the number 2 connecting rod fractured from the crankshaft. Metallurgical examination of the connecting rod, and associated bolts, nuts, and bearings, showed that following the first nut and bolt separation, the overall separation was not instantaneous. After the first nut unthreaded from its respective bolt, subsequent increased loads on the opposite bolt then stripped the threads of the other nut that had partially unthreaded from its bolt. Furthermore, there was no evidence of cotter pin installation. In general, a properly torqued nut and connecting rod bolt will not loosen under normal operational conditions. The engine underwent a field overhaul 735.31 hours prior to the accident. At 233.59 hours prior to the accident, the cylinders were removed for a blow by condition during an annual inspection; however, the aviation maintenance technician who performed this work stated that he did not remove the connecting rods from the crankshaft. Review of the autopsy results and impact damage to the wreckage indicated that the occupants' use of shoulder harnesses would have significantly increased their chances of survival.

Quoted verbatim from the NTSB record.