ENGINES
TROUBLESHOOTING
COMMON HELICOPTER GAS TURBINE ENGINE PROBLEMS R. Fred Polak | Editor
I have spoken with numerous operators and discussed what they consider to be some of the more common
gas turbine engine problems they have encountered, and the solutions to those problems. Since I am in no way, shape or form an engine specialist, I gladly accept these operators’ input and share it with you. If you consider yourself to be a gas engine turbine specialist, please feel free to skip this part of the article. However, if you are not an engine person, I encourage you to read on. You just might learn something.
Jet Engines Jet or gas turbine engines, as they are commonly called, are usually thought of as producing thrust for aircraft and not used as the driving force for gear boxes and rotor blades as they are in helicopter applications. Turboshaft or turboprop engines are gas turbine engines that do not produce thrust. They take power from the production of thrust and turn it into mechanical power to drive rotors or propellers. The way the turbine blades are shaped determines whether they change thrust into great amounts of power to drive a shaft, or if they allow most of
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HelicopterMaintenanceMagazine.com April | May 2014
the thrust to be used as propulsion and take a small amount of drive power away to drive the compressor section of the engine.
In just about all helicopters where a gas turbine engine is
used, the engine is a turboshaft engine. These engines are light weight, powerful and more reliable than reciprocating engines as there are fewer moving parts. How does a gas turbine turboshaft engine work? Four
words are all it takes to describe its operation: suck, squeeze, burn and blow. The front of the engine is the compressor section which
“sucks” in air and “squeezes” it to make it denser and better for combustion. Air is brought into the compressor by the turning compressor blades that are shaped like small airfoils. It works like a very powerful fan to move air into the engine. Between the moving rows of compressor blades are stationary blades called stators. The stators help shape the direction of the airfl ow and help in the compression process. As the air moves through the compressor section the
volume the air can occupy gets smaller. This helps to heat the air on its way to the diff user and then on to the combustion chamber. Here the air is mixed with fuel and ignited and we
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