Aviation International Rotors CH-54A N44094

Summary

On 8 July 2007 at about 23:08 local time, a Aviation International Rotors CH-54A registered N44094 was involved in an accident near Los Olivos, California, United States. 2 people were on board and 2 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

8 July 2007 at 23:08

Classification

Accident

Location

Los Olivos, California, United States

Coordinates

Not recorded

Aircraft

Aviation International Rotors CH-54A

Registration

N44094

Category

Helicopter

Engines

2

Operator

Not recorded

Operating rule

Part 133: Rotorcraft Ext. Load

Purpose of flight

Fire Fighting

Phase of flight

Not recorded

Route

Los Olivos → Los Olivos

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

LAX07LA210

2 people had minor injuries.

The company mechanic's inadequately performed maintenance and inspection, which resulted in a flight control malfunction and loss of control during takeoff.

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

Read the full NTSB narrative

The pilot was preparing to takeoff in furtherance of a contract firefighting flight for the California Department of Forestry & Fire Protection (CAL FIRE). The helicopter was on the ground with its engines at operational power, when a mechanical malfunction occurred. The pilot was unable to maintain roll control, and the helicopter initiated an uncommanded slow rollover onto its side. The helicopter was operated and maintained by its owner pursuant to a specific maintenance program. A component of this program involved examining each main rotor servo mount pin for rust and corrosion, and performance of dimensional checks prior to reinstallation of the inspected components. The company mechanic reported that he completed the inspection and found no faults. The records reflect that the components were reassembled and installed on the helicopter that was then returned to service. The accident occurred about 8 operational hours and 2 days following the reported maintenance inspection. During the accident investigation, components that secured one of the three main rotor blade pitch change servo units to the helicopter were found a few yards away from the main wreckage. The components consisted of a nut, bolt, pin, and plate. The components had secured one of the servo units to the helicopter transmission on one end and the helicopter swash plate on the other end. Separation of these components from the helicopter resulted in separation of the servo unit, and consequently resulted in a loss of main rotor blade pitch control. Upon the subsequent visual examination of components, evidence of severe wear and corrosion was detected inside of the nut holding down the retainer mounting strap, which indicates that this area had not been inspected for some time. Once the main rotor servo cylinder and transmission attaching lug separated, the rotor system would travel to the full pitch position, thereby resulting in the helicopter experiencing an uncommanded lift and roll to the right.

Quoted verbatim from the NTSB record.