Casualties unknown

1999-09-06: Bell UH-1H (N4085L) — Silverton, CO

Silverton, CO, US

On September 6, 1999, a Bell UH-1H (registration N4085L) was involved in an aviation accident near Silverton, CO. Investigators recorded the probable cause as: The total loss of engine power for undetermined reasons. A factor was the lack of suitable terrain for a forced landing. 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 helicopter transporting construction materials suffered engine failure during a hover at a high-altitude mine, leading to an autorotation and main rotor ground impact.

Accident Overview

A helicopter accident occurred while the pilot was transporting construction materials to a mine. The pilot, on his first trip of the morning, was hovering approximately 300 pounds of cargo suspended from the helicopter while ground personnel disconnected the cargo net. During this operation, a member of the ground team radioed the pilot reporting that 'fire and smoke was coming from your tail pipe.' The pilot then noticed that the rotor rpm warning light was illuminated, and the engine out lights and horns had been activated. He subsequently lowered the collective and initiated an autorotation to the ground. However, during the descent, the main rotor blades impacted the terrain.

Aircraft Information

The aircraft involved was the helicopter registered as N4085L. According to aircraft records, the engine was sourced from a civilian overhaul facility and had been installed in N4085L approximately 21 hours prior to the accident.

Environmental Conditions

The accident site was at a mine entrance with an elevation reported by the Colorado Department of Minerals and Mines as 11,500 feet. The density altitude at the time was calculated to be 13,000 feet.

Cargo Details

The pilot was transporting approximately 300 pounds of construction materials. The cargo was on the ground and the helicopter was in a hover when ground personnel were disconnecting the cargo net.

Engine Failure Indications

The pilot received a warning from ground personnel about fire and smoke emanating from the tail pipe. Simultaneously, cockpit warnings activated, including the rotor rpm warning light and engine out lights and horns.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001212X19738. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.