Brantly B-2B N9018Y

Summary

On 24 July 2005 at about 15:25 local time, a Brantly B-2B registered N9018Y was involved in an accident near Plymouth, Massachusetts, United States. 2 people were 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

24 July 2005 at 15:25

Classification

Accident

Location

Plymouth, Massachusetts, United States

Nearest airport

Plymouth Municipal Airport (PYM)

Coordinates

41.9147, -70.7367

Aircraft

Brantly B-2B

Registration

N9018Y

Category

Helicopter

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

Plymouth → Unknown

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

IAD05LA107

Nobody was injured.

Fatigue failure of the intermediate tailrotor driveshaft, which resulted in a loss of directional control at a hover.

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

Read the full NTSB narrative

While at a hover, the helicopter made an uncommanded sharp turn to the right, which could not be arrested with a left pedal application. When the helicopter completed approximately 3/4 of a rotation, the pilot "chopped the power" to stop the spin. The helicopter descended, struck the left skid on the ground, and then rolled over onto its left side. Examination of the intermediate tailrotor gearbox revealed that the tailrotor driveshaft was fractured at the input side of the gearbox. A portion of the fractured driveshaft remained in the flanged bushing of the gearbox. The fractured pieces of the driveshaft displayed significant mechanical damage from the driven end of the driveshaft after the fracture occurred. The driveshaft section recovered from the intermediate gearbox input bevel displayed multiple fatigue fractures with multiple origins around the attach-bolt holes. The fractures propagated from the attach-bolt holes in the direction of rotation, and opposite the direction of rotation. Fractured tail rotor vertical driveshafts from two previous events in the same make and model displayed almost identical modes of failure. As a result of those examinations, the FAA issued Airworthiness Directive 2006-08-07 on May 2, 2006, to help prevent fatigue cracking and subsequent failures of the vertical shaft.

Quoted verbatim from the NTSB record.