Sikorsky CH-54A N9125M

Summary

On 16 October 1999 at about 21:10 local time, a Sikorsky CH-54A registered N9125M was involved in an accident near Elko, Nevada, United States. 3 people were on board and one died. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

16 October 1999 at 21:10

Classification

Accident

Location

Elko, Nevada, United States

Nearest airport

Elko Municipal-J.c. Harri (EKO)

Coordinates

40.9496, -115.7894

Aircraft

Sikorsky CH-54A

Registration

N9125M

Category

Helicopter

Engines

2

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Positioning

Phase of flight

Not recorded

Route

Tooele → Yuba City

Aircraft damage

Not recorded

Weather

VMC

Light

Day

NTSB number

LAX00LA018

1 person died.

the flight engineer's decision to climb a step ladder that put him in close proximity to the still turning main rotor blades. The gusting wind was a factor in the accident.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

While the aircraft was shutting down, the flight engineer exited the aircraft, and gave the pilots the signal that the droop stops had engaged. He then climbed up on a stepladder next to the tail boom as the main rotor continued to coast down to a stop. A minute or so later, the two remaining crewmembers heard a 'thump.' The pilot-in-command (PIC) asked the copilot to go outside and find the source of the noise. When he walked toward the rear of the aircraft he found the flight engineer laying across the top of tail boom with a massive head injury. The main rotor of the Ch-54A is fully articulated. The rotor system employs a series of main rotor blade droop stops. As the rotor rpm slows, centripetal force is reduced and the droop stop springs pull the stops back into ground stop position. During spool down it can take 20 seconds or more for the first through sixth stop to move into the ground stop position. The visual strobe effect, caused by the turning rotor head, can make it appear that all the stops are in place when one or more stops still have not yet been fully repositioned. Winds were gusting up to 14 knots at the time of the shutdown. Gusting winds during shutdown can cause a slow turning rotor blade to suddenly flap down independently of the remaining blades.

Quoted verbatim from the NTSB record.