Hughes 269C N1093N

Summary

On 22 January 1998 at about 16:15 local time, a Hughes 269C registered N1093N, operated by Gary L. Nunley, was involved in an accident near Brackettville, Texas, United States. 2 people were on board and one had minor injuries. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

22 January 1998 at 16:15

Classification

Accident

Location

Brackettville, Texas, United States

Coordinates

29.3099, -100.4093

Aircraft

Hughes 269C

Registration

N1093N

Category

Helicopter

Engines

1

Operator

Gary L. Nunley

Operating rule

Part 91: General Aviation

Purpose of flight

Public Use

Phase of flight

Not recorded

Route

Bacon Ranch → Unknown

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

FTW98TA104

1 person had minor injuries.

failure of splines on the drive shaft coupling after separation of the forward bubber boot and loss of lubrication (grease), which resulted in a disconnect of the rotor drive system and an autorotation/forced landing. Lack of suitable terrain in the forced landing area was a related factor.

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

Read the full NTSB narrative

The pilot and a crewmember/gunner of the public use helicopter reported hearing a loud squealing noise, emanating from the rear of the helicopter, while in flight at 75 feet AGL. Rotor RPM began decaying from 3,100 to approximately 2,000 RPM, and the pilot initiated an autorotation. During the landing, the main rotor blades contacted the ground, and helicopter came to rest in a rocky dry creek bed on its right side. The tension nut for the short shaft was found upstream from the point of impact. An examination revealed that splines for the drive shaft coupling were damaged, and the plating on the adapter was discolored as result of excessive heat. Further examination revealed that the damage sustained by the shaft and adapter were consistent with loss of grease and subsequent overheating and destruction of the drive splines. The forward rubber boot, used to retain the lubricant, had separated, resulting in the loss of lubrication.

Quoted verbatim from the NTSB record.