Wednesday, April 13, 2016

Hughes 369, N298SD: Accident occurred April 08, 2016 in Weatherford, Parker County, Texas

http://registry.faa.gov/N298SD

FAA Flight Standards District Office:  FAA Fort Worth AFW FSDO-19


NTSB Identification: GAA16LA182 
14 CFR Part 91: General Aviation
Accident occurred Friday, April 08, 2016 in Weatherford, TX
Probable Cause Approval Date: 01/18/2017
Aircraft: HUGHES 369, registration: N298SD
Injuries: 1 Serious.

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

The pilot/mechanic stated that, while performing maintenance on the helicopter, he locked the left side antitorque (tail rotor) pedals to keep them out of the way; however, he forgot to unlock them after completing the maintenance. The pilot then conducted a post-maintenance hover check, and, upon increasing collective, the helicopter entered a spin, traveled about 40 feet, and collided with a building and trees. 

The pilot stated that there were no preimpact mechanical failures or malfunctions with the airframe or engine that would have precluded normal operation, and that the accident was the result of his failure to remove the antitorque pedal lock before flight. 

The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
The pilot/mechanic's inadequate postmaintenance and preflight inspections, which resulted in his failure to remove the antitorque pedal lock and a subsequent loss of control during hover operations.

On April 8, 2016, about 0930 central daylight time, a MD Helicopters (formerly Hughes) 369A helicopter, N298SD, collided with a building and trees during takeoff at the Staggs Heliport (TE93), Weatherford, Texas. The commercial pilot/airframe and power plant mechanic sustained serious injuries, and the helicopter sustained substantial damage. The helicopter was registered to, and operated by the pilot as a day, visual flight rules (VFR) flight under the provisions of 14 Code of Federal Regulations Part 91 as a maintenance check flight. Visual meteorological conditions prevailed and no flight plan was filed. The flight originated from the Staggs Heliport (TE93), about 0930.

The pilot/mechanic submitted a written statement to the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on April 30, and stated that during a battery installation on the helicopter, he "locked" the left side anti-torque (tail rotor) pedals in the cockpit to keep them out of the way during the battery installation and forgot to "unlock" them. While conducting a powered maintenance check after an engine installation on the ground, he stated that he was checking the governor and had his seat restraint system on in the right seat for when he "goes to the top end." He stated that he "pulled collective to check at a hover" and the helicopter departed the ground, spun several times, traveled about 40 feet, and collided with a building and trees. The pilot/mechanic sustained serious injuries from the accident sequence. The pilot/mechanic further stated that this was a maintenance error.

The helicopter sustained substantial damage to the main rotor system, the fuselage, the tailboom, and the tail rotor system. 

The pilot/mechanic verified that there were no preimpact mechanical failures or malfunctions with the airframe or engine that would have precluded normal operation.

AIRCRAFT INFORMATION

The accident helicopter was originally manufactured as an OH-6A for the US Army. After the completion of service with the US Army, the helicopter was issued a standard airworthiness certificate by the Federal Aviation Administration (FAA). 

WRECKAGE AND IMPACT INFORMATION

The photographs of the wreckage supplied by the FAA aviation safety inspector (ASI) showed that the helicopter came to rest with its left side against a small group of trees in close proximity to a residential building and both of the skids had collapsed. Three of the four main rotor blades exhibited several bends at various locations through the length of the blades due to impacting the trees and building while one main rotor blade separated at the blade root. The bottom of the fuselage exhibited crushing consistent with a downward impact with terrain and the tailboom was bent at about the midpoint between the tail rotor and the fuselage. The tailboom was also crushed inward on the left side, just forward of the tail rotor system. The lower vertical fin displayed impact damage on the lower left side.

Inside the cockpit, the anti-torque pedals on the right side were observed with the left anti-torque pedal positioned in place with an adjustment pin installed at the top of the pedal arm and the right anti-torque pedal was also positioned in place but did not have an adjustment pin installed at the top of the pedal arm. On the left side of the cockpit, the left anti-torque pedal was displaced from the pedal arm and lying against the center console with the adjustment pin missing and the right anti-torque pedal was positioned in place with an adjustment pin installed at the top of the pedal arm. The center section of the right side cockpit windshield was punctured during the accident sequence. 

On the right side of the cockpit, the FAA ASI reported that underneath the floor board was various mechanic tools. He further reported that it appears that this foreign object debris did not contribute to the accident. 

ADDITIONAL INFORMATION

Preflight Checklist

Excerpts from the US Army Operators Manual Helicopter Observation OH-6A TM 55-1520-214-10 (1976) for the preflight checklist are available in the public docket for this accident.

Anti-Torque Control System

Excerpts from the US Army Operators Manual Helicopter Observation OH-6A TM 55-1520-214-10 (1976) for the anti-torque control system are available in the public docket for this accident.

MD Helicopters Service Letter SL369H-124R3

MD Helicopters has published Service Letter SL369H-124R3 (2004). This document describes the maintenance and operation requirements of surplus 369A (OH-6A) series helicopters and states in part:

Failure to comply with established FAA regulations, airworthiness directives, mandatory retirement, overhaul life limits, and proper inspection and maintenance procedures may lead to loss of control of the helicopter and subsequent injury, death and/or property damage.

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