GAS TURBINES EXAM 4 - CG
QUESTIONS AND ANSWERS WITH
COMPLETE SOLUTIONS (GRADED A+)
Lubricating oil contamination in a gas turbine bearing oil sump will most
likely come from which of the following?
(a) Failure of the lube oil pump.
(b) Fuel oil contamination.
(c) Failure of the scavenging pump.
(d) Failure of seal pressurization air.
✓ (d) Failure of seal pressurization air.
Your first step in response to a gas turbine engine high lube oil sump
temperature alarm would be which of the following?
(a) Check the oil filter differential pressure.
(b) De-couple the engine from the main reduction gear.
(c) Check the oil pressure to the sump.
(d) Reduce engine speed.
✓ (d) Reduce engine speed.
In order to get a ready indication for a normal start with a GE LM2500
marine gas turbine, what permissive(s) must be met?
(a) Fuel supply pressure must be greater than 8 psig.
(b) Bleed air valve must be closed.
(c) Gas generator speed must be less than 1200 RPM and all engine trips reset.
(d) All of the above.
✓ (d) All of the above.
In which of the following ways can compressor surge cause excessive temperatures
in the turbine section?
(a) By providing inadequate secondary air
, (b) By overloading the compressor
(c) By providing excessive combustion air
(d) All of the above -ANSWER✔✔a
The six borescope ports located in the compressor rear frame casing of the marine
propulsion gas turbine shown, can be used to inspect all EXCEPT which of the
following components? Illustration GT-0006
(a) 14th stage compressor blades.
(b) Fuel nozzles.
(c) Combustor.
(d) 1st stage turbine nozzle -ANSWER✔✔a
When conducting a borescope inspection, you must be aware of all of the
following factors EXCEPT which?
(a) The inspection areas and ports.
(b) The engineer's experience.
(c) The internal reference points.
(d) The limitations of your equipment. -ANSWER✔✔b
You are preparing for a borescope inspection of a GE LM2500 gas turbine engine.
You are reviewing the correct geometric orientation nomenclature which includes
which of the following?
(a) All references left, right, and radial are orientated as viewed from aft looking
forward on the engine.
(b) All references left, right, and radial are orientated as viewed from forward
looking aft on the engine.
(c) All references are made from the combustor section, forward to the hp turbine
and aft to the power turbine.
QUESTIONS AND ANSWERS WITH
COMPLETE SOLUTIONS (GRADED A+)
Lubricating oil contamination in a gas turbine bearing oil sump will most
likely come from which of the following?
(a) Failure of the lube oil pump.
(b) Fuel oil contamination.
(c) Failure of the scavenging pump.
(d) Failure of seal pressurization air.
✓ (d) Failure of seal pressurization air.
Your first step in response to a gas turbine engine high lube oil sump
temperature alarm would be which of the following?
(a) Check the oil filter differential pressure.
(b) De-couple the engine from the main reduction gear.
(c) Check the oil pressure to the sump.
(d) Reduce engine speed.
✓ (d) Reduce engine speed.
In order to get a ready indication for a normal start with a GE LM2500
marine gas turbine, what permissive(s) must be met?
(a) Fuel supply pressure must be greater than 8 psig.
(b) Bleed air valve must be closed.
(c) Gas generator speed must be less than 1200 RPM and all engine trips reset.
(d) All of the above.
✓ (d) All of the above.
In which of the following ways can compressor surge cause excessive temperatures
in the turbine section?
(a) By providing inadequate secondary air
, (b) By overloading the compressor
(c) By providing excessive combustion air
(d) All of the above -ANSWER✔✔a
The six borescope ports located in the compressor rear frame casing of the marine
propulsion gas turbine shown, can be used to inspect all EXCEPT which of the
following components? Illustration GT-0006
(a) 14th stage compressor blades.
(b) Fuel nozzles.
(c) Combustor.
(d) 1st stage turbine nozzle -ANSWER✔✔a
When conducting a borescope inspection, you must be aware of all of the
following factors EXCEPT which?
(a) The inspection areas and ports.
(b) The engineer's experience.
(c) The internal reference points.
(d) The limitations of your equipment. -ANSWER✔✔b
You are preparing for a borescope inspection of a GE LM2500 gas turbine engine.
You are reviewing the correct geometric orientation nomenclature which includes
which of the following?
(a) All references left, right, and radial are orientated as viewed from aft looking
forward on the engine.
(b) All references left, right, and radial are orientated as viewed from forward
looking aft on the engine.
(c) All references are made from the combustor section, forward to the hp turbine
and aft to the power turbine.
