Continental Copters Inc. TOMCAT MK5A N9005T accident near Le Sueur, Minnesota

Probable cause

The pilot's inadequate preflight and in-flight fuel planning, during which he did not visually check the fuel quantity in the fuel tanks and instead relied on the fuel gauges that were showing erroneous fuel quantity indications, which resulted in fuel exhaustion and the subsequent loss of engine power during cruise flight.

NTSB analysis

The commercial pilot stated that, during the preflight inspection of the helicopter before the agricultural flight, there were about 23 gallons of fuel onboard, which he determined was sufficient to complete the 45- to 60-minute flight to his destination. The pilot stated that, before departure, the helicopter fuel gauge indicated "close" to 3/4 full. Based on the helicopter's total fuel capacity (41 gallons), a 3/4-fuel quantity indication would have equated to about 30 gallons. About 50 minutes into the flight and 7 miles from the destination airport, the engine lost power. The pilot performed an autorotation to a field, during which the helicopter impacted terrain and sustained substantial damage.

During postaccident examination of the helicopter, no usable fuel was found; however, the fuel gauge indicated a little over a 1/4 tank of fuel remaining. The examination revealed that the fuel transmitter's resistive element was corroded. The fuel transmitter was tested, and the resistive values were uncorrelated to the transmitter's float position. A new fuel transmitter from the operator's parts department was tested, and the resistive values corresponded to the float position no anomalies were noted. Although the fuel gauge was indicating that a sufficient amount of fuel was onboard for the flight, the pilot should have visually checked the fuel quantity in the tanks before takeoff to ensure that a sufficient amount of fuel was onboard for the flight, which he did not do. His improper preflight fuel planning and his dependence on erroneous fuel gauges led to the subsequent fuel exhaustion and total loss of engine power.

Text from the NTSB. Open the NTSB docket for CEN18LA300 for the full record.