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Aviation Accident

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NTSB Identification: LAX05LA060
The docket is stored in the Docket Management System (DMS). Please contact Records Management Division
14 CFR Part 91: General Aviation
Accident occurred Monday, January 03, 2005 in Casa Grande, AZ
Probable Cause Approval Date: 02/28/2006
Aircraft: Eurocopter France EC135T1, registration: N135NW
Injuries: 1 Minor, 1 Uninjured.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

Following the in-flight separation of a main rotor control link, the pilots lost control and the helicopter hit the ground hard and rolled over. The pilots reported that as they turned base in the traffic pattern for landing at the airport, the helicopter pitched up violently and rolled to the right, followed by a hard roll to the left. Both pilots got on the controls and tried to regain control of the helicopter. The pilots lowered the collective and started down for a landing. During the descent, the pitching and rolling continued intermittently with the roll attitude reaching beyond 60 degrees. As the helicopter neared the ground, the pilots flared and the helicopter hit the ground in a tail low attitude and rolled over. A post accident examination of the helicopter, and examination of maintenance records by a Federal Aviation Administration inspector, occurred on site and after recovery. During the course of the examination it was determined that maintenance personnel had removed cyclic control links from the cyclic control levers to check the ball joints for excess free play during an inspection. The links are attached to the cyclic levers with bolts and castle nuts with cotter pins through the castle nuts as a safety locking device. The right lateral cyclic control link was found broken. The nut on the upper bolt was 1/4-inch away from the side of the attachment point. There was no evidence of the cotter pins having been added to the castle nuts after the link inspection/reinstallation.

The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
  • the separation of a main rotor control link due to improper maintenance installation.