Hughes 369D N500EK

Summary

On 17 September 2002 at about 02:35 local time, a Hughes 369D registered N500EK was involved in an accident near O'Neill, Nebraska, United States. 2 people were on board and one had minor injuries. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

17 September 2002 at 02:35

Classification

Accident

Location

O'Neill, Nebraska, United States

Coordinates

42.4858, -98.6456

Aircraft

Hughes 369D

Registration

N500EK

Category

Helicopter

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

Fort Dodge → Ainsworth

Aircraft damage

Substantial

Weather

VMC

Light

Night/Dark

NTSB number

CHI02LA285

1 person had minor injuries.

A loss of engine power due to turbine blade separation as a result of hot corrosion damage to the turbine blades. Contributing to the accident was the pilot misjudging the flare at the completion of the autorotation resulting in a hard landing. The dark night was a factor.

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

Read the full NTSB narrative

The helicopter was substantially damaged during a forced landing following a complete loss of engine power during cruise flight at night. The pilot stated that during the flight, the engine failed, the emergency annunciator lights illuminated, and he felt a yaw due to the loss of full torque. He executed an autorotation to a bean field. The pilot stated that it was very dark and that depth perception was difficult and he flared too soon and "ran out of lift at about 10-12 feet above the ground." The helicopter subsequently impacted the ground. The main rotor blades sheared off the front right upper portion of the cabin and the tailboom. Examination of the engine at the accident site revealed that the N1 rotor system would not rotate. Subsequent examination revealed that the first stage turbine wheel had all of the blades broken off 0.2 to 0.4 inch above the rim at the leading edge and 0.1 to 0.15 inch above the rim at the trailing edge. Scanning electron microscope examination of the fractures revealed no fatigue progression. The fracture surface was oxidized and the macroscopic features were interdendritic, indicating that separation occurred in overload. A metallographic section of one of the blades was made. This section showed a loss of metal as a result of hot corrosion. Distinct spherical particles were observed ahead of the corrosion front, consistent with sulfadation. The chemistry of the spherical particles was found to be rich in sulfur. Examination of the second stage turbine wheel also showed features consistent with hot corrosion damage. Further examination of the submitted items showed that the microstructure, hardness and chemistry conformed to the engineering drawing requirements.

Quoted verbatim from the NTSB record.