AIRCRAFT ACCIDENT INVESTIGATION

Aircraft Accident Investigation and Turbine engines



Aircraft Accident Investigation and Turbine engines

Introduction

Investigating the engine aspects of aviation accidents is a complex, difficult challenge. This is especially true when the new high technology gas turbine engines now in use in commercial aviation are involved. The investigator, even if familiar with the traditional tools and techniques of power plant investigation must update this knowledge to include the design aspects and failure modes of these new engines.

Aircraft Accident Investigation

Jet engines in use on today's commercial airliners are quite reliable. It is not uncommon for engines to operate for tens of thousands of hours without difficulty before being removed from service for scheduled inspection. However, engine malfunctions or failures occasionally occur that require an engine to be shut down in flight(Krause 1996). Since multiengine airplanes are designed to fly with one engine inoperative and flight crews are trained to fly with one engine inoperative, the in-flight shutdown of an engine typically does not constitute a safety of flight issue. Following an engine shutdown, a precautionary landing is performed with airport fire and rescue equipment positioned near the runway. Once the airplane lands, fire department personnel assist with inspecting the airplane to ensure it is safe before it taxis to the gate.

When an accident occurs it is investigated by the government with jurisdiction over the area where a plane goes down. The sole objective of the investigation of an accident or incident is the prevention of accidents and incidents. It is not the purpose to apportion blame or liability. The results of investigations are used to ascertain measures that would best tend to prevent similar accidents or incidents in the future. The investigation includes the field investigation (on-scene at the accident, testing, teardown, etc.), report preparation, and, where ordered, a public hearing. The investigation results in Board conclusions issued in the form of a report or “brief” of the incident or accident(McCormick 2007). Accident/incident investigations are fact-finding proceedings with no formal issues and no adverse parties. They are not subject to the provisions of the Administrative Procedure Act, and are not conducted for the purpose of determining the rights or liabilities of any person.

Turbine engine investigation

The two turbine engines commonly in use today are the turbojet and turbo shaft. The turbine has surpassed the piston engine in design efficiency. The advantages of the gas turbine are a high power-to-weight ratio, less maintenance, and low oil consumption. Because of the small frontal area, turbines have less aerodynamic drag(Khan 2008). The disadvantages are foreign object damage to the compressor vanes, high operating temperatures, and high fuel consumption. The turbine also has a slower acceleration rate. Because of the high operating rpm, all rotating parts must be in perfect balance. The cost to manufacture a turbine is much higher than that of a reciprocating engine. Aircraft designers have always been limited by the power-plants available for use on aircraft of new design. Their constant plea has been for higher power, less weight, and a more ...