Thursday, June 16, 2016

Eurocopter EC-120B, Department of Homeland Security, N372HS: Accident occurred June 13, 2016 in Ajo, Pima County, Arizona


FAA Flight Standards District Office:  FAA Scottsdale FSDO-07

NTSB Identification: GAA16CA318
14 CFR Public Use
Accident occurred Monday, June 13, 2016 in Ajo, AZ
Probable Cause Approval Date: 09/12/2016
Aircraft: EUROCOPTER EC120, registration: N372HS
Injuries: 1 Uninjured.

NTSB investigators used data provided by various entities, including, but not limited to, the Federal Aviation Administration and/or the operator and did not travel in support of this investigation to prepare this aircraft accident report.

The pilot of a skid equipped helicopter reported that after landing on a volcanic rock hill top, the pilot exited the running helicopter. The pilot further reported that he heard an audible change in the sound of the main rotor and observed the ground under the right skid of the helicopter give way and the helicopter rolled to the right.

The helicopter sustained substantial damage to the tail boom.

According to the pilot there were no preimpact mechanical failures or malfunctions with the airframe or engine that would have precluded normal operation. 

The Federal Aviation Administration (FAA) has published FAA-H-8083-21A Helicopter Flying Handbook (2012). This handbook discusses pilots at the flight controls and states in part:

"Many helicopter operators have been lured into a "quick turnaround" ground operation to avoid delays at airport terminals and to minimize stop/start cycles of the engine. As part of this quick turn-around, the pilot might leave the cockpit with the engine and rotors turning. Such an operation can be extremely hazardous if a gust of wind disturbs the rotor disk, or the collective flight control moves causing lift to be generated by the rotor system. Either occurrence may cause the helicopter to roll or pitch, resulting in a rotor blade striking the tail boom or the ground. Good operating procedures dictate that, generally, pilots remain at the flight controls whenever the engine is running and the rotors are turning".

The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
The pilot's decision to exit the helicopter with the engine and rotors turning and the selection of unsuitable terrain for a landing, which resulted in a roll over.

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