MD Helicopters 369 N551CP

Summary

On 16 August 2012 at about 05:50 local time, a MD Helicopters 369 registered N551CP, operated by Columbus Police, was involved in an accident near Columbus, Ohio, United States. 2 people were 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

16 August 2012 at 05:50

Classification

Accident

Location

Columbus, Ohio, United States

Coordinates

39.9701, -83.0102

Aircraft

MD Helicopters 369

Registration

N551CP

Category

Helicopter

Engines

1

Operator

Columbus Police

Operating rule

Public Use

Phase of flight

Not recorded

Route

Columbus → Columbus

Aircraft damage

Substantial

Weather

VMC

Light

Night

NTSB number

CEN12TA550

Nobody was injured.

The failure of a 4th-stage turbine blade due to high-cycle fatigue, which resulted in the loss of engine power.

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

Read the full NTSB narrative

The pilot reported that, shortly after leveling off the helicopter at 1,500 ft mean sea level, he heard a "loud exploding noise" coming from the rear of the helicopter followed by a "long sustained whining noise" coming from the engine and a constant warning tone in the background. The pilot then saw the gas producer (N1) and power turbine (N2) gauge needles falling rapidly. He identified the situation as an engine failure, so he performed an autorotation. The helicopter subsequently touched down on a street, slid, rotated counterclockwise about 1 1/2 turns, then came to a stop. The main rotor blades contacted a utility pole adjacent to the street, and the tail fin, stabilizer, and tail rotor broke off. A postaccident examination of the engine revealed that a 4-inch segment of the 4th-stage turbine shroud was fractured in the plane of the 4th-stage turbine wheel. The 4th-stage turbine was missing one blade, and the blade had fractured off near the inner platform. A three-blade span of the related segment of the rim was also missing. An examination of the missing blades' fracture surfaces showed evidence consistent with high-cycle fatigue likely caused by an engine speed/airframe interaction of unknown origin, which resulted in the blade failure and subsequent loss of engine power.

Quoted verbatim from the NTSB record.