Robinson R44 II N4174P

Summary

On 20 September 2009 at about 21:40 local time, a Robinson R44 II registered N4174P was involved in an accident near Valley Center, California, United States. 2 people were on board and 2 were seriously injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

20 September 2009 at 21:40

Classification

Accident

Location

Valley Center, California, United States

Nearest airport

Ramona (RNM)

Coordinates

33.1339, -116.9197

Aircraft

Robinson R44 II

Registration

N4174P

Category

Helicopter

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

San Diego → San Diego

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

WPR09LA460

2 people were seriously injured.

The failure of the engine’s camshaft due to fatigue of unknown origin.

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

Read the full NTSB narrative

The pilot was performing a pinnacle landing on a large boulder. As he approached the landing zone at an altitude of between 50 and 75 feet above ground level he heard a popping sound followed by a complete loss of engine power. He performed an autorotation, during which the helicopter sustained substantial damage to the fuselage and tail boom. during the hard landing. The helicopter was manufactured about 11 months prior to the accident, had accumulated about 130 total flight hours, and was equipped with its original engine. Examination of the engine revealed that the camshaft had separated into two sections at the forward relief radius of the number six exhaust cam lobe. The fracture surfaces were damaged by the continued rotation of the engine just after the failure; however, the remaining surfaces exhibited features consistent with fatigue. The origin of the fatigue could not be determined. No other anomalies were noted with the engine or airframe. According to the engine manufacturer, the camshaft supplier had produced 4,870 camshafts of the accident type. All of these camshafts have since been installed in similar engines. A search of the Federal Aviation Administration (FAA) Service Difficulty Report (SDR) database revealed no evidence of a similar camshaft separation. Additionally, the engine manufacturer reported no prior instances of any camshaft which had failed in such a manner.

Quoted verbatim from the NTSB record.