Casualties unknown

1986-06-26: Bell 47G2 (N984B) — Lisbon, OH

Lisbon, OH, US

On June 26, 1986, a Bell 47G2 (registration N984B) was involved in an aviation accident near Lisbon, OH. Investigators recorded the probable cause as: The ground crewman's decision to jump from the chemical truck into the arc of the helicopter's main rotor while it was rotating at high idle. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 1781061362Data APIEditorial standards

A ground crewman was fatally injured after jumping from a chemical truck into the arc of a turning main rotor while an aerial application helicopter was being serviced.

What happened

An aerial application helicopter was undergoing servicing operations when a fatal incident occurred. A chemical truck was parked directly adjacent to the aircraft to facilitate the transfer of chemicals. At the time of the event, the helicopter's engine was operating at high idle, and the main rotor system was rotating at 250 RPM.

The ground crewman involved in the operation reportedly boarded the chemical truck from its rear section. While positioned on or near the vehicle, he jumped off the side of the chemical truck directly into the arc of the helicopter's main rotor blades. The impact with the rotating blades sustained fatal injuries to the crewman.

The investigation

The investigation focused on the operational context of the aerial application servicing. It was established that the helicopter engine remained at high idle throughout the incident, keeping the main rotor in motion. The proximity of the chemical truck to the aircraft created a confined workspace where the rotating blade arc overlapped with the area where the ground crewman was moving.

Findings

The primary factor contributing to this accident was the ground crewman's movement into the hazard zone of the rotating main rotor. Despite the engine being at high idle, the rotor continued to turn at 250 RPM, presenting a lethal threat to anyone within its radius. The incident highlights the critical danger posed by unshielded helicopter rotors during ground servicing operations, particularly when support vehicles are positioned adjacent to the aircraft.

fuel exhaustion is not applicable here; the causal fact was unauthorized entry into the rotor arc. The crewman's action of jumping from the truck placed him directly in the path of the blades. No other mechanical failures or weather conditions were cited as contributing factors.

Safety message

Personnel involved in aerial application operations must maintain strict awareness of the helicopter's rotor status at all times. Even when an engine is at high idle, the main rotor remains a significant hazard. Ground crew should never enter the rotor arc while the engine is running, regardless of the perceived speed or power level. Clear communication and established safety zones are essential to prevent similar incidents during servicing.

Probable cause

The ground crewman's decision to jump from the chemical truck into the arc of the helicopter's main rotor while it was rotating at high idle.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001213X33753. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.