What is a wet start on a jet engine?
A faulty start of a gas turbine engine in which ignition fails to take place or a self-sustaining RPM is not achieved. The unburned or burning fuel is ejected from the tailpipe.
What is hot start and hung start?
The “hung” start happens when an engine is accelerating towards idle RPM, with normal combustion, and an extraction of bleed air occurs. As the airflow through the engine is too low you can easily overshoot the max. EGT (hot start)by introducing more fuel which it depending on the time of the EGT.
What causes a wet start?
A wet start occurs when the engine fails to light up in a certain period of time when fuel is introduced into the combustion chamber. The indication of a wet start to the pilot is a positive rise and stabilisation of high pressure compressor with no rise in engine exhaust temperature.
What is a hot start turbine?
In an aircraft with a reciprocating fuel injected engine a hot start is a condition where an engine start is attempted after it has been run, achieved operating temperature, and then recently shut down. Unlike a turbine engine, a hot start is unlikely to damage a reciprocating fuel injected engine.
How do aircraft reciprocating engines work?
Reciprocating engines operate on the basic principle of converting chemical energy (fuel) into mechanical energy. This conversion occurs within the cylinders of the engine through the process of combustion. (Fuel-air mixture is the ratio of the “weight” of fuel to the “weight” of air in the mixture to be burned.)
What is Dry motoring?
A- dry motoring is setting power lever to rpm higher than idle without using fuel, while wet motoring using fuel . B- dry motoring is setting power lever to rpm less than idle without using fuel or air, while wet motoring using fuel .
What does creep of the turbine blades mean?
Creep is the natural tendency of a material to gradually move or permanently deform as a result of mechanical stress or strain. For turbines, creep can cause the blades to elongate, which can ultimately lead to the blade beginning to damage or pierce the turbine casing.
How do I stop a hot start?
Always follow the Starting Engine checklist and pay close attention to engine instruments during a start. Do not attempt a start when rushed or distracted. During a start, airflow through the engine controls the temperature of the combusting fuel. Spinning the compressor with the starter provides the required airflow.
What is an engine hung start?
A hung start occurs when the engine starts but doesn’t accelerate to idle speed. This indicates a problem wherein the HMU/ECU falls off the acceleration schedule or fails to bring the secondary fuel nozzles online. Cut the fuel off and motor the engine.
What is an engine wet start?
Re: what is the “engine wet start”？. A wet start is one where for some reason you did not get ignition to light up the fuel. At this point you will have to do the wet start process before actually starting the engine – most often (but not always) involves a spooling of the engine to “blow” out the excess fuel.
What is a wet start in an airplane?
, Airline pilot. A wet start does no harm to the engine. A wet start occurs when the engine fails to light up in a certain period of time when fuel is introduced into the combustion chamber. The indication of a wet start to the pilot is a positive rise and stabilisation of high pressure compressor with no rise in engine exhaust temperature.
How does a dry motor start a jet engine?
If you do a manual start on a jet engine, putting the start switch to start opens the start valve which lets apressurised air turn the starter motor. At a preset N2 (or N3 on RR), you open the HP cock. This turns on the ignitors and opens the Lp and HP fuel cocks. A dry motor is starter motor only, you do not open the HP cock.
How do you check for a wet motor?
Useful for checking for hyd leaks as the hyd pump is going at max pressure, and checking the start system. A wet motor, you trip the ignition CBs, and operate the start switch, and open the HP cock. This introduces fuel (wet) but it does not ignite.