Pilot Debrief

ROBINSON HELICOPTER R44 near Rowlett, TX — 2023-10-26

Final reportCEN24LA027
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Date
2023-10-26
Location
Rowlett, TX, USA
Aircraft
ROBINSON HELICOPTER R44
Registration
N141CD
Category
Helicopter
Highest injury
Minor
Fatalities
0

Probable cause

A malfunction of the helicopter’s Engine Monitoring Unit (EMU)/Governor Controller for undetermined reasons. Contributing to the accident was the flight instructor’s failure to turn off the EMU/Governor Controller per the emergency checklist when the malfunction first occurred.

Contributing factors

Contributing to the accident was the flight instructor’s failure to turn off the EMU/Governor Controller per the emergency checklist when the malfunction first occurred.

NTSB narrative

While in level flight, the flight instructor heard the engine and rotor rpm increase, followed by the high rotor rpm horn. The flight instructor reduced the throttle and subsequently observed another increase in engine and rotor rpm as if the throttle were fully open. The flight instructor again reduced the throttle, then observed rpm fluctuations and suspected they had a governor failure. He attempted overgripping the throttle but said it had limited effect in controlling the rpms. Concerned with the prospect that the engine could fail at any moment, the flight instructor initiated an autorotation as the engine fluctuations could not affect flight if they were unmarried to the rotor. The pilot selected a dirt field off the nose of the helicopter and began their descent. The field had been recently plowed, and recent rain showers made the field muddy. During the touchdown on the field, the skids dug into the dirt and the helicopter nosed forward, which resulted in the main rotor contacting the ground. The helicopter spun violently and then came to rest upright. The helicopter sustained substantial damage to the main rotor, tail rotor, tail boom, and empennage. The helicopter’s Engine Monitoring Unit (EMU)/Governor Controller was retained for further examination. The EMU/Governor Controller was a single unit that maintained the engine rpm in the governing range. Engine and rotor rpm were related as long as the rotor was not in a freewheel/autorotation condition. The EMU side of the unit just recorded data. Operational testing of the unit did not replicate the issue the flight crew experienced. No anomalies were found that would have precluded the unit’s normal operation. Per the helicopter’s Pilot Operating Handbook, the emergency procedure for a governor failure was to grip the throttle firmly to override the governor and then switch the governor off before completing the flight using the manual throttle control. The flight instructor reported that, although he thought he attempted to disable the governor, post-flight he was not sure if they had accomplished it or not. Had the pilot followed the emergency checklist and disabled the governor, they would have likely maintained some throttle control during the emergency landing.

NTSB coding

View NTSB final report

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