Schweizer 269C N75070

Summary

On 28 February 2004 at about 19:00 local time, a Schweizer 269C registered N75070 was involved in an accident near Media, Pennsylvania, 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 February 2004 at 19:00

Classification

Accident

Location

Media, Pennsylvania, United States

Coordinates

39.9167, -75.4167

Aircraft

Schweizer 269C

Registration

N75070

Category

Helicopter

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Instructional

Phase of flight

Not recorded

Route

Medford → Unknown

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

IAD04LA013

Nobody was injured.

A lack of previous lubrication to the tail rotor drive shaft forward fitting teeth, which resulted in their gradual wear, the eventual slippage of the shaft, and the subsequent loss of tailrotor thrust and forced landing.

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

Read the full NTSB narrative

The student pilot was flying the helicopter in cruise flight, at 800 feet, when a loss of tail rotor thrust occurred, with a "sharp metallic-sounding squeal." The student pilot then performed an autorotation which resulted in a hard landing. Examination of the tail rotor drive shaft, forward fitting teeth, revealed smearing and rubbing in the middle of the tooth surfaces. A wear/rubbing failure mechanism had been previously seen on other helicopters, that resulted from insufficient lubrication. Although the forward fitting had a significant amount of grease on it, it could not be confirmed whether grease had always been present. No significant manufacturing defects were found. With over 3,000 helicopters in service, only two similar events had been attributed to insufficient lubrication, and both occurred on same helicopter model within the previous year. Shaft loading, which was "relatively light," only required minimal lubrication to a design that had remained essentially unaltered since the 1960s. The shaft, which required an inspection every 300 hours, had last been inspected 180 hours before the accident.

Quoted verbatim from the NTSB record.