Wolf ROTORWAY EXEC-162F N1955Z

Summary

On 7 October 2002 at about 22:30 local time, a Wolf ROTORWAY EXEC-162F registered N1955Z was involved in an accident near Gregory, Michigan, 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

7 October 2002 at 22:30

Classification

Accident

Location

Gregory, Michigan, United States

Coordinates

42.4500, -84.0500

Aircraft

Wolf ROTORWAY EXEC-162F

Registration

N1955Z

Category

Helicopter

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Instructional

Phase of flight

Not recorded

Route

Howell → Unknown

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

CHI03LA006

Nobody was injured.

Failure of the secondary drive shaft, which resulted in a complete loss of power to the main rotor, and a high forward airspeed on touchdown, causing the helicopter to flip forward.

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

Read the full NTSB narrative

While in cruise flight, the secondary drive shaft failed completely and power to the main rotor was lost. The pilot executed an autorotation to an open field. However, on landing, the forward speed was higher than planned and the helicopter flipped forward and rolled to the left. The pilot stated that on his return to the airport, the secondary shaft bearing temperature started to rise. Once the bearing temperature reached 150 degrees Fahrenheit, the "drive let go", causing the engine RPM to surge. A post-accident inspection revealed that the secondary shaft had failed at a point inside the upper bearing race. Due to a history of failures of this secondary shaft design, Rotorway had released a 35 mm diameter shaft configuration in April 2001. The preceeding shaft diameter was 30 mm. An advisory bulletin was issued by Rotorway in May 2002. The 30 mm configuration was installed on the accident aircraft. In addition, the accident aircraft incorporated an after-market cog belt drive system between the secondary shaft and the main rotor shaft. The basic Rotorway design utilizes a chain drive system.

Quoted verbatim from the NTSB record.