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ASN Wikibase Occurrence # 153768
Last updated: 21 September 2021
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Type:Silhouette image of generic EC35 model; specific model in this crash may look slightly different
Eurocopter EC 135T1
Owner/operator:Native American Air Ambulance
Registration: N135NW
MSN: 0010
Fatalities:Fatalities: 0 / Occupants: 2
Aircraft damage: Substantial
Location:near Casa Grande, AZ -   United States of America
Phase: Unknown
Departure airport:Mesa, AZ (IWA)
Destination airport:Casa Grande, AZ (CGZ)
Investigating agency: NTSB
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.
Probable Cause: the separation of a main rotor control link due to improper maintenance installation.




Revision history:

05-Mar-2013 08:01 TB Added
07-May-2016 10:43 Aerossurance Updated [Time, Aircraft type, Destination airport, Source, Narrative]
21-Dec-2016 19:28 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
06-Dec-2017 06:52 ASN Update Bot Updated [Operator, Other fatalities, Departure airport, Destination airport, Source, Narrative]

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