Pilot Debrief

ROBINSON HELICOPTER COMPANY R44 II near Gunnison, UT — 2016-08-12

Final reportWPR16LA165
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Date
2016-08-12
Location
Gunnison, UT, USA
Aircraft
ROBINSON HELICOPTER COMPANY R44 II
Registration
N247DB
Category
Helicopter
Highest injury
None
Fatalities
0
Phase of flight
Initial climb

Probable cause

A total loss of engine power for reasons that could not be determined based on the available evidence.

NTSB narrative

The commercial pilot was nearing the end of his second agricultural application pass; about the time that he turned off the spray system, he heard a "pop" and felt a "thump" that shook the helicopter. After he observed chemical spray in the air and along the side of the helicopter, he pushed the "kill" button for the spray pump. As he was doing so, the engine rpm dropped, and the pilot heard the engine "sputtering." The pilot lowered the collective to re-establish main rotor rpm; the engine subsequently experienced a total loss of power. He entered an autorotation between 50 and 75 ft above the ground, and the helicopter landed hard. The spray system was recently installed, and the helicopter had flown about 16 hours since the installation. The spray system pump was mounted on the right side skid. The engine air filter compartment was located above and behind the spray pump. A postaccident examination of the spray system revealed that the plastic pipe nipple on the spray system fractured. The initial crack progressed through the wall of the nipple during flight and caused a pesticide leak. Examination of the internal and external surfaces of the engine intake air filter revealed no cake deposits. Because there was no evidence of chemical residue on the airframe between the engine and the air intake filter and the condition of the air filter was relatively clean, it is unlikely that the engine ingested enough chemical to cause the total loss of power. Additionally, the operator later had the engine successfully run in a test cell with no anomalies noted; therefore, the reason for the loss of engine power could not be determined.

Analysis

Primary failure mode
Engine power loss
First missed decision gate
Pilot could have checked the spray system before the second pass.

NTSB coding

Evidence available

  • Photos
  • 5 docket documents
View NTSB final reportView NTSB docket

Docket documents5

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