Bell Helicopter Textron Canada 407 N407KS

Summary

On 28 December 2012 at about 18:15 local time, a Bell Helicopter Textron Canada 407 registered N407KS, operated by King County Sheriffs Office, was involved in an accident near Renton, Washington, 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

28 December 2012 at 18:15

Classification

Accident

Location

Renton, Washington, United States

Nearest airport

Renton Municipal Airport (RNT)

Coordinates

47.4892, -122.2094

Aircraft

Bell Helicopter Textron Canada 407

Registration

N407KS

Category

Helicopter

Engines

1

Operator

King County Sheriffs Office

Operating rule

Public Use

Phase of flight

Not recorded

Route

Renton → Renton

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

WPR13TA081

Nobody was injured.

The pilot's failure to maintain helicopter control during takeoff from an unstable landing platform. Contributing to the accident was the operator's inadequate chocking procedures for the wheeled landing platform, which included chocking only two of the platforms four rear wheels and led to the platform's instability.

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

Read the full NTSB narrative

The commercial pilot was conducting a public aircraft flight in the helicopter. The pilot reported that the helicopter was located on an 18-inch-high portable landing platform with eight sets of casters, including four fixed rear casters. The pilot reported that, while he was preparing for departure, he increased the throttle, and the helicopter and platform started to rotate. A witness reported that the helicopter lifted up about 1 foot, shifted forward, and then came down hard on the front of the platform, which caused the platform to rotate. Although the pilot attempted to stop the rotation, he was unsuccessful, and the helicopter began to spin. As the helicopter spun, it tipped rearward, and the tail rotor struck the ground. The helicopter's right landing skid came off the platform. The helicopter and cart stopped rotating, and the pilot shut down the engine. The operator reported that it had only been chocking two of the four fixed rear casters on the platform, which, they determined postaccident, resulted in the platform being unstable. The pilot likely prematurely lifted off, touched back down on the forward edge of the unstable platform, and subsequently lost helicopter control when the platform began to rotate.  

Quoted verbatim from the NTSB record.