Fatigue failure of a compressor blade

Abstract

A helicopter in a commercial flight was substantially damaged during a hard landing following a loss of engine power at Northwest region of Brazil. The pilot and passengers reported no injuries. Initial investigations pointed out absence of any damages by foreign objects. The accident was due to the failure of a blade from compressor section. Failure analysis of 4th stage disk showed that the blade failed due to fatigue which started from corrosion pits.

Introduction

Gas turbine engines are largely used as power plants at fixed-wings and rotary-wings aircraft. They have a small device with a great power-to-weight ratio. Basically a gas turbine engines ingest air from the atmosphere, compress the incoming air to high pressure, add fuel at combustion chamber and burn to produce hot inlet gases at high-velocity that drive the turbine section which extracts the energy [1].

Failure in gas turbine engines components is current [2], [3], [4], [5] and components most commonly rejected are the blades from both the compressor and the turbine vanes [6]. Turbine compressor blades play important role at turbine and are designed and fabricated to operate at high temperatures and aggressive environments.

The blades are under constant cyclic loading this way metallurgical and mechanical property degradation of the material occurs during service, which can limit the useful life service. Corrosion can affect aircraft structural integrity since fatigue cracks can nucleate from corrosion pits and grow at an accelerated rate [7].

In this work, it was investigated the engine failure of a helicopter in the Northeast region of Brazil. The helicopter was substantially damaged during a hard landing following a loss of engine power.