Arrow Falcon Exporters OH-58C N912HP

Summary

On 23 June 2008 at about 14:00 local time, a Arrow Falcon Exporters OH-58C registered N912HP, operated by Double Tree Helicopters, was involved in an accident near Fresno, 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

23 June 2008 at 14:00

Classification

Accident

Location

Fresno, California, United States

Coordinates

36.7761, -119.7181

Aircraft

Arrow Falcon Exporters OH-58C

Registration

N912HP

Category

Helicopter

Engines

1

Operator

Double Tree Helicopters

Operating rule

Part 137: Agricultural

Purpose of flight

Aerial Application

Phase of flight

Not recorded

Route

Fresno → Unknown

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

LAX08LA195

Nobody was injured.

The loss of engine power due to fatigue failure of a second stage compressor blade.

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

Read the full NTSB narrative

The pilot reported that he had filled the spray tanks with water and had lifted off from a platform on the back of a truck when he heard three loud noises followed by a loss of engine power. The pilot initiated a hovering autorotation to the landing platform; however, was only able to maneuver the forward portion of the helicopter over the platform. Subsequently, the helicopter slid off the platform and impacted the ground tail boom first, resulting in structural damage to the tail boom and fuselage. Examination of the engine revealed that 15 third stage compressor vanes were fractured near the root and had separated. The majority of the separated vanes were located in the lower compressor case half. The remaining attached vanes were bent over in the direction of engine rotation. A single second stage compressor vane located in the lower case halve was fractured near the root and had liberated. Multiple third and fourth stage compressor blades had leading edge damage. One second stage vane airfoil was separated and the area of separation was found consistent with high cycle fatigue (HCF). An additional second stage vane airfoil exhibited a crack, consistent with HCF near the root, but it did not separate. A Semi-quantitative x-ray energy dispersive analysis (XEDA) revealed deposits at the suction side vane root were consistent with oxidized braze alloy, indicating the braze alloy was exposed during engine operation. It was also found that the chemistry, microstructure and hardness of the second stage vanes were consistent with component specifications.

Quoted verbatim from the NTSB record.