Aviation Accident Summary ANC12CA100

Talkeetna, AK, USA

Aircraft #1

N178CH

AEROSPATIALE AS350 B2

Analysis

The pilot landed a high-skid, turbine-powered helicopter at a remote construction site, which contained several bags of cement that were covered by a plastic tarp. The plastic tarp was secured by a nylon strap that was wrapped around the bags. The pilot reported that after landing near the bags of cement, he retarded the engine throttle to flight idle to begin the mandatory 2-minute engine cool down procedure. During the engine cool down, the pilot felt an abrupt airframe vibration, so he immediately closed the engine throttle and performed an emergency engine shutdown. A postflight inspection revealed that the plastic tarp had dislodged from the nylon strap, and it subsequently became entangled in the tail rotor hub and blade assembly. As a result, the helicopter sustained substantial damage to the tail rotor drive system and tailboom. The pilot said there were no preaccident mechanical anomalies with the helicopter that would have precluded normal operation.

Factual Information

The pilot landed a high skid, turbine-powered helicopter at a remote construction site, which contained several bags of cement that were covered by a plastic tarp. The plastic tarp was secured by a nylon strap that was wrapped around the bags. The pilot reported that after landing near the bags of cement, he retarded the engine throttle to flight idle to begin the mandatory 2-minute engine cool down procedure. During the engine cool down the pilot felt an abrupt airframe vibration, so he immediately closed the engine throttle, and did an emergency engine shutdown. A postflight inspection revealed that the plastic tarp had dislodged from the nylon strap, and it subsequently became entangled in the tail rotor hub and blade assembly. As a result, the helicopter sustained substantial damage to the tail rotor drive system and tail boom. The pilot said there were no preaccident mechanical problems with the helicopter.

Probable Cause and Findings

The entanglement of a plastic tarp in the helicopter’s tail rotor after becoming dislodged from its securement.

 

Source: NTSB Aviation Accident Database

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