Aerospatiale AS350BA N31621

Summary

On 6 June 1998 at about 07:25 local time, a Aerospatiale AS350BA registered N31621 was involved in an accident near Burbank, California, United States. One person was on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

6 June 1998 at 07:25

Classification

Accident

Location

Burbank, California, United States

Coordinates

Not recorded

Aircraft

Aerospatiale AS350BA

Registration

N31621

Category

Helicopter

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Positioning

Phase of flight

Not recorded

Route

Lake Arrowhead → Van Nuys

Aircraft damage

Substantial

Weather

VMC

Light

Night/Dark

NTSB number

LAX98LA184

Nobody was injured.

The separation of the tail rotor pitch link due to a fatigue fracture, which resulted in the separation of the tailboom.

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

Read the full NTSB narrative

The pilot felt a 'violent vibration' and the helicopter began to pitch and yaw. About 5 seconds after the vibration started, the tail rotor gearbox chip light became illuminated. The pilot made a normal approach to a rooftop parking structure and landed. The last 3 feet of the tail boom had separated 360 degrees in circumference. Examination of the tail rotor system revealed one pitch change link disconnected due to a fatigue fracture, which emanated from multiple origins at the inside diameter surface of the loop that is in contact with the bearing assembly. The scrim cloth for the bearing assembly raceway was missing, and the bearing outer raceway contained wear damage approximately 180 degrees around its circumference. A maximum of 0.008 inches of play is allowed in the radial direction between the ball and the pitch change link assembly; however, no limit is specified for the axial direction. The pilot reported that he completed a required daily inspection of the aircraft the day before the accident and observed no play in either tail rotor pitch link, nor did he see any cracks. He also reported that he performed a preflight before takeoff on the accident flight and did not note any discrepancies at that time.

Quoted verbatim from the NTSB record.