Eurocopter COLIBRI EC120B N122TH

Summary

On 26 February 1999 at about 15:10 local time, a Eurocopter COLIBRI EC120B registered N122TH was involved in an accident near Springtown, Texas, United States. One person was 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

26 February 1999 at 15:10

Classification

Accident

Location

Springtown, Texas, United States

Coordinates

32.9602, -97.6794

Aircraft

Eurocopter COLIBRI EC120B

Registration

N122TH

Category

Helicopter

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Business

Phase of flight

Not recorded

Route

Grand Prairie → Amarillo

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

FTW99LA085

1 person had minor injuries.

The improper touchdown executed by the pilot. Factors were the tail wind condition, and the manufacturer's inadequate design of the P3 pipe supports, which resulted in a fatigue fracture of the P3 pipe.

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

Read the full NTSB narrative

While at cruise altitude, the helicopter's engine began to surge. The pilot initiated an autorotation to an open field. During the downwind forced landing, the skids dug into the ground, and the helicopter nosed over and came to rest on its left side. An examination of the engine revealed that the P3 air pipe, which supplies air to the fuel control, was broken close to the fitting on the combustion chamber casing. Examination of the P3 pipe revealed that its fracture was 'consecutive to the propagation of a fatigue fissure,' as a result of the pipe being 'subjected to an excessive vibratory excitation.' Engine vibration tests were conducted and two main excitation sources were identified. The two sources were the starter-generator and the breather gear assembly. The proposed solution to correct for this vibration consists of fitting an attachment clamp at mid-length of the P3 pipe, 'which moves the natural frequencies out of engine power ratings.'

Quoted verbatim from the NTSB record.