Pilot Debrief

BELL 47G-4A near Montgomery City, MO — 2011-06-18

Final reportCEN11CA403
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Date
2011-06-18
Location
Montgomery City, MO, USA
Aircraft
BELL 47G-4A
Registration
N24HM
Category
Helicopter
Highest injury
None
Fatalities
0
Phase of flight
Takeoff roll

Probable cause

A loss of control during the precautionary landing, which resulted in inadvertent contact between the main rotor and the tailboom. Contributing to the accident was the overloaded condition.

NTSB narrative

The pilot reported that he had returned from an agricultural application to reload the cleaning solution. Unbeknownst to the pilot, the helicopter was loaded with approximately 90 gallons of solution, instead of the expected 70 gallons for the flight. The pilot reported that he increased engine power and lifted off; however, immediately after lift off the engine and rotor speed began to decrease. He selected a suitable landing point and flared for touchdown about 10 feet above ground level to minimize the forward speed. The helicopter touched down on the rear portion of the landing skids and began to pitch forward. He applied aft cyclic control to prevent the helicopter from nosing over. He subsequently heard a bang and observed debris coming from the aircraft. He shut down the engine and secured the helicopter. A postaccident examination revealed that the main rotor had struck the tailboom resulting in substantial damage to the airframe. The pilot said the helicopter may have been on a slight incline when the solution was loaded, allowing the right side tank to fill more than the left side tank. He was unaware of the overload condition. The pilot added that closer monitoring of the helicopter and chemical truck incline, and the final amount of solution being loaded onto the helicopter, might have prevented the accident. The pilot did not report any failures or malfunctions that would have precluded normal operation.

Analysis

Primary failure mode
Human factors
First missed decision gate
Closer monitoring of loading conditions could have prevented the overload.

NTSB coding

Evidence available

  • 2 docket documents
View NTSB final reportView NTSB docket

Docket documents2

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