What aircraft was involved and where did it happen?

The accident on 2003-07-06 involved a Bell 47 G5, registration N7938J, at Salinas, CA.

Helicopter Engine Failure Leads to Tail Boom Contact During Aerial Application (N7938J)

On July 6, 2003, a Bell 47 G5 (registration N7938J) was involved in an aviation accident near Salinas, CA. Investigators recorded the probable cause as: The failure of the number 3 piston connecting rod, which led to an in-flight engine shutdown and subsequent loss of control during landing. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.

A commercial pilot experienced a violent engine shutdown during an aerial application flight, resulting in a run-on landing that caused the main rotor to strike the tail boom and sever the gearbox.

What happened

The commercial pilot was conducting an aerial application flight when he reported executing several passes with the helicopter. During the downwind leg of the accident approach, the engine shuttered violently before quitting completely. The pilot initiated a run-on landing sequence to manage the loss of power.

During the landing phase, the main rotor blade made contact with the tail boom of the helicopter. This impact resulted in the severing of the tail rotor gearbox. The aircraft sustained significant structural damage during this uncontrolled touchdown.

The investigation

Investigators conducted an external inspection of the helicopter engine and observed that the aft section of the engine case was ruptured. To determine the root cause of the failure, the engine was disassembled for a thorough examination.

Findings

Upon disassembly, the number 3 piston connecting rod was discovered to be broken. This mechanical failure within the engine is identified as the primary cause of the sudden loss of power that precipitated the accident sequence.

Probable cause

The failure of the number 3 piston connecting rod, which led to an in-flight engine shutdown and subsequent loss of control during landing.

2003-07-06: Bell 47 G5 (N7938J) — Salinas, CA