Robinson R44 N8361X

Summary

On 3 September 2009 at about 20:00 local time, a Robinson R44 registered N8361X, operated by Universal Air Academy, was involved in an accident near Torrance, 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

3 September 2009 at 20:00

Classification

Accident

Location

Torrance, California, United States

Nearest airport

Zamperini Field Airport (TOA)

Coordinates

33.8033, -118.3394

Aircraft

Robinson R44

Registration

N8361X

Category

Helicopter

Engines

1

Operator

Universal Air Academy

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

La Verne → Torrance

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

WPR09LA436

Nobody was injured.

A main rotor overspeed due to the pilot’s failure to maintain rotor RPM within allowable limits during a practice autorotation.

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

Read the full NTSB narrative

The pilot reported that he initiated a practice autorotation to a paved helipad. As the helicopter descended through about 100 feet agl, the pilot initiated a recovery by “slowly rolling on throttle.” The pilot stated that as the helicopter descended, he noticed the rotor RPM “increase quickly.” Subsequently,the helicopter landed on the helipad uneventfully. Post accident examination of the helicopter revealed that the tail boom of the helicopter was structurally damaged, and the tail rotor drive shaft was bent and separated in multiple locations. The drive shaft exhibited scoring around the circumference at regularly spaced intervals on the shaft. The damper assembly was heavily damaged, and the intermediate flex coupling assembly was damaged. According to the helicopter’s manufacturer, this damage to the tail rotor drive shaft is indicative of a rotor over speed to at least 134%. No pre-accident mechanical anomalies were noted with the engine or airframe that would have precluded normal operation.

Quoted verbatim from the NTSB record.