Abnormal Starts π― Flashcards
What is a hung start
When the rpm is not increasing at the rate expected
Causes of a hung start
Starter cutting out too early due to a fault
May be caused by insufficient fuel flow due to a fault
May be VIGVs or bleed valves or the compressor not responding to the start command
Indications of a hung start
Engine rpm will stop increasing
EGT will be too high for that rpm and may continue increasing
Remedy for a hung start
Cut of fuel and dry motor to remove any fuel inside and to reduce the temperature
What is a hot start
Engine temperatures exceed limits.
Concerned with the TIT, ITT, EGT
Causes of a hot start
The fuel-air ratio is too rich meaning:
Not enough airflow through the compressor
Too much fuel for the airflow
Indications of a hot start
EGT rises beyond limits
A slowly rising rpm
Actions to remedy a hot start
Cut off the fuel and dry motor the engine to starve fuel and reduce temperatures
What is a wet start
When there is a failure of ignition once fuel has been introduced
Causes of a wet start
Igniters not functioning properly
Indications of a wet start
No EGT rise
Fuel vapour coming from tailpipe
Rpm will we the same as the starter motor as this is all thatβs turning the engine
Actions to take in a wet start
Cut off the fuel supply and motor the engine via the starter without fuel to purge the fuel from the combustion chamber
Danger of a wet start
Generally nothing but if a second attempt to start is attempted then the extra fuel ignited in the combustion can result in torching
What will happen if the bleed valves in the compressor do not open during start
An overpressure will occur resulting in a compressor stall or surge
What will happen if the bleed valves are stuck open during start
The compressor will not be able to maintain its normal pressure
