Pilot Debrief

Enstrom 280 near Hayden, ID — 2020-06-24

Final reportWPR20LA191
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Date
2020-06-24
Location
Hayden, ID, USA
Aircraft
Enstrom 280
Registration
N280MM
Category
Helicopter
Highest injury
Fatal
Fatalities
1
Phase of flight
Initial climb

Probable cause

The total loss of power while maneuvering at low altitude due to the detonation of two engine cylinders and damaged spark plugs.

NTSB narrative

Shortly after takeoff on an instructional flight, a helicopter was maneuvering at a low altitude when the engine rpm “skyrocketed,” and the engine lost total power; the flight instructor (who was at the controls) reported hearing “backfiring” at the time, although the engine was still running. The flight instructor then had to maneuver the helicopter to avoid nearby power lines, but the helicopter impacted terrain. The main rotor blades struck the tailboom, and the helicopter subsequently spun around about 180° before coming to rest. A postcrash fire then ensued, which consumed most of the helicopter. Additionally, the student pilot stated to a witness after the accident that the helicopter was losing power. An engine examination revealed that detonation had occurred in two of the four engine cylinders. (Detonation in a piston engine occurs when the fuel-air mixture in a cylinder detonates or explodes prematurely instead of being ignited by spark plugs and burning evenly and smoothly, as occurs with normal combustion.) Furthermore, damaged spark plugs were observed in one of the detonated cylinders as well as another cylinder. The combined effects of the detonation and damaged spark plugs likely caused the loss of engine power. Because the loss of power occurred at a low altitude, the flight instructor likely did not have enough altitude to adequately establish a steady-state autorotation to avoid the helicopter’s impact with terrain.

Analysis

Primary failure mode
Engine power loss
First missed decision gate
Proper engine maintenance before the flight could have prevented power loss.

NTSB coding

Evidence available

  • 11 docket documents
View NTSB final reportView NTSB docket

Docket documents11

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