Beechcraft A45 N434M

Summary

On 23 June 2013 at about 21:43 local time, a Beechcraft A45 registered N434M, operated by Jet Test and Transport LLC, was involved in an accident near Boulder City, Nevada, 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

23 June 2013 at 21:43

Classification

Accident

Location

Boulder City, Nevada, United States

Nearest airport

Boulder City (BVU)

Coordinates

35.9667, -114.8833

Aircraft

Beechcraft A45

Registration

N434M

Category

Airplane

Engines

1

Operator

Jet Test and Transport LLC

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

Chandler → North Las Vegas

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

WPR13FA284

2 people died.

The pilot/mechanic's loss of control during an emergency descent following a loss of engine power while in cruise flight. Contributing to the accident was the pilot/mechanic's incorrect assembly of the No. 6 cylinder at the last cylinder change, which resulted in a separation of the cylinder and the loss of engine power.

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

Read the full NTSB narrative

The pilot, who was also the mechanic for the airplane, had replaced all six cylinders on the engine during the airplane's annual inspection; he reported that, 3 days before the accident, the engine was operated and ran well. On the day of the accident, he was returning the airplane to its home base following a maintenance inspection on the wings. The pilot was near the end of the flight when he contacted approach control and requested priority handling because an engine chip light had illuminated. Shortly thereafter, the pilot stated that the engine had lost power on a cylinder, and he declared an emergency. When the airplane was at 9,500 ft mean sea level, the pilot said that he was going to attempt to land at a nearby airport (elevation 2,201 ft). Before switching to the airport's common traffic advisory frequency (CTAF), the pilot reported to the approach controller that the airplane was at 3,800 ft with the landing gear down and that the situation was under control. The pilot did not contact approach control again and did not broadcast over the CTAF. The airplane collided with terrain in a nose- low attitude about 1 mile west of the airport. Postaccident examination of the airframe revealed no evidence of mechanical anomalies that would have precluded normal operation. Postaccident examination of the engine revealed that the No. 6 cylinder had separated, and no nuts were located on its through bolts. Magnified examinations of the bolt threads found the thread profiles intact and only locally distorted, consistent with the nuts not being present during the No. 6 cylinder separation, which appeared to be the result of the incorrect assembly of the cylinder at the last cylinder change. Fretting damage on the mounting pad was observed, which indicates looseness and movement between the cylinder and the case that resulted from inadequate preload in the fasteners either through insufficient initial torque or loss of torque during operation. Considering the short time since cylinder installation, it is likely that the cylinder fasteners, or at least some of them, were not correctly torqued at installation.

Quoted verbatim from the NTSB record.