GT Flashcards
What is stall?
The breakdown of laminar airflow over the compressor blades, from incorrect relative velocity within a compressor stage
What causes stall?
Incompatible air inlet velocity or rational speed
What are the symptoms of stall?
Slow acceleration, especially on start up
Unusual noise from engine or intake
Rapid rise in turbine inlet temperature
Fluctuations in spool speed
How do we prevent stall and surge?
Compressor air bleed valves
Multi spool engines
What is blade creep?
The phenomena where a piece of material will lengthen over time
What is caused by blade creep?
Crucial clearances concerning blade length can become minimised and even lead to high speed contact, resulting in catastrophic failure
What are the oil tests?
Appearance
Water content
Total alkalinity number
Viscosity
Viscosity index
Elemental oil analysis
Purpose of a wet motor?
Rotation of engine with fuel but no flame
Prove on engine fuel system
Occasion for a wet motor?
Checking for fuel leaks
Setting to work fuel system auxiliaries
Priming on engine fuel system
Setting to work new or replacement engines
Responsibilities of GTAA?
To ensure close control of the international gas turbine change units pool necessary for an adequate exchange service
The management of certain GTCU spares
To provide close liaison with operational, maintenance, store, freight authorities and foreign navies
The purpose of hourly based routines?
To assess the condition of the engine and components throughout its working life and allow exchange of components before catastrophic failure takes place
What is a basin trial?
Full machinery and systems check alongside with strict limitations of delivered power
What is a large repair trial?
Elements of propulsion performance trial
What is a post upkeep trial?
Full package of bring alive trials, safety and readiness check
What is a propulsion performance assessment?
Authorised full power for a timed period in order to obtain a full set of S346 readings for comparison with other readings
Full set of S346 readings to be returned to machinery trials team
