NAVY AVIATION MACHINIST STUDY GUIDE 2026/2027
QUESTIONS AND SOLUTIONS RATED A+
✔✔APU Fuel System - ✔✔(1) Fully automatic system
(2) Supplies required fuel under all operating conditions
(3) Receives its fuel from the the aircraft fuel system
✔✔APU Lubricating System - ✔✔(1) Provides both pressurized and splash lubrication
for all gears, shafts, and bearings within the engine
✔✔APU Ignition System - ✔✔(1) Capacitor discharge type that consists of an ignition
exciter, ignitor lead, and ignitor plug
✔✔Electronic Sequence Unit - ✔✔(1) Provides the APU with programmed events such
as starting, operational checks, and overspeed protection
✔✔APU Safety Control System - ✔✔(1) Provides automatic starting of the APU.
Includes safety features to shut down the unit automatically or manually
✔✔APU Safety Control System shuts down automatically when - ✔✔Oil Pressure falls
below minimum specified limits, Turbine exceeds maximum RPM, and Maximum
temperature is exceeded
✔✔APU Safety Control System can be shut down manually by actuating the APU
control switch in the flight station / cockpit to the OFF position so that - ✔✔In case of
fire, the APU fire warning light in the flight station / cockpit illuminates
Pulling the T-handle of the APU control switch arms the fire extinguisher and removes
28 volts DC from the control switch
✔✔Operation / Maintenance (APU) - ✔✔(1) Power is developed through compression
ambient air by a centrifugal compressor
(2) Compressed air is mixed with fuel that is ignited to drive the turbine
(3) Rotating shaft power of the turbine wheel drives the compressor, accessories, and
main output drive pad
✔✔Maintenance O Level - ✔✔(1) Periodic inspection
(2) Removal and replacement of components
(3) Complete removal and replacement of the APU
, ✔✔Engine Lubrication System's Purpose - ✔✔To provide an adequate supply of clean
oil to the bearings and gears at the right temperature and pressure
✔✔Types of Engine Lubrication Systems - ✔✔Wet Sump and Dry Sump
✔✔Wet Sump - ✔✔(1) Stores oil within the gearbox and does not have an external tank
(2) Used primarily on the centrifugal-flow engines
✔✔Dry Sump - ✔✔(1) Stores oil in a separate oil tank external of the engine
(2) Allows for larger supply of oil
(3) Used primarily on the axial-flow engines
✔✔Lubrication System Components - ✔✔Reservoir / Oil Tank, Lubrication System
Valves, Lubrication System Pumps, Lubrication System Filters Lubrication System Heat
Exchangers, Lubrication Jets (Nozzles), and Oil Pressure Transmitter
✔✔Reservoir / Oil Tank's Purpose - ✔✔Stores the system's oil supply
✔✔Reservoir / Oil Tank Components - ✔✔Vent, Deaerator, Oil Level Transmitter,
Coarse Mesh Screens, Various oil and air inlets and outlets
✔✔Vent - ✔✔Controls air pressure in the tank to ensure a constant supply of oil to the
main oil pump
✔✔Deaerator - ✔✔Seperates air from oil returning to the oil tank
✔✔Oil Level Transmitter - ✔✔Can be a Dip Stick or Sight Gauge or even an actual
transmitter that send electrical signal to an oil level indicator in the cockpit
✔✔Coarse Mesh Screens - ✔✔Collects contaminants
✔✔Various oil and air inlets and outlets - ✔✔Holes
✔✔Lubrication System Valves - ✔✔Pressure Relief Valve, Check Valve, and Bypass
Valve
✔✔Pressure Relief Valve - ✔✔Limits maximum pressure where the valve opens, and
returns the excess oil to the inlet side of the pump
✔✔Check Valve - ✔✔Allows flow in one direction only
QUESTIONS AND SOLUTIONS RATED A+
✔✔APU Fuel System - ✔✔(1) Fully automatic system
(2) Supplies required fuel under all operating conditions
(3) Receives its fuel from the the aircraft fuel system
✔✔APU Lubricating System - ✔✔(1) Provides both pressurized and splash lubrication
for all gears, shafts, and bearings within the engine
✔✔APU Ignition System - ✔✔(1) Capacitor discharge type that consists of an ignition
exciter, ignitor lead, and ignitor plug
✔✔Electronic Sequence Unit - ✔✔(1) Provides the APU with programmed events such
as starting, operational checks, and overspeed protection
✔✔APU Safety Control System - ✔✔(1) Provides automatic starting of the APU.
Includes safety features to shut down the unit automatically or manually
✔✔APU Safety Control System shuts down automatically when - ✔✔Oil Pressure falls
below minimum specified limits, Turbine exceeds maximum RPM, and Maximum
temperature is exceeded
✔✔APU Safety Control System can be shut down manually by actuating the APU
control switch in the flight station / cockpit to the OFF position so that - ✔✔In case of
fire, the APU fire warning light in the flight station / cockpit illuminates
Pulling the T-handle of the APU control switch arms the fire extinguisher and removes
28 volts DC from the control switch
✔✔Operation / Maintenance (APU) - ✔✔(1) Power is developed through compression
ambient air by a centrifugal compressor
(2) Compressed air is mixed with fuel that is ignited to drive the turbine
(3) Rotating shaft power of the turbine wheel drives the compressor, accessories, and
main output drive pad
✔✔Maintenance O Level - ✔✔(1) Periodic inspection
(2) Removal and replacement of components
(3) Complete removal and replacement of the APU
, ✔✔Engine Lubrication System's Purpose - ✔✔To provide an adequate supply of clean
oil to the bearings and gears at the right temperature and pressure
✔✔Types of Engine Lubrication Systems - ✔✔Wet Sump and Dry Sump
✔✔Wet Sump - ✔✔(1) Stores oil within the gearbox and does not have an external tank
(2) Used primarily on the centrifugal-flow engines
✔✔Dry Sump - ✔✔(1) Stores oil in a separate oil tank external of the engine
(2) Allows for larger supply of oil
(3) Used primarily on the axial-flow engines
✔✔Lubrication System Components - ✔✔Reservoir / Oil Tank, Lubrication System
Valves, Lubrication System Pumps, Lubrication System Filters Lubrication System Heat
Exchangers, Lubrication Jets (Nozzles), and Oil Pressure Transmitter
✔✔Reservoir / Oil Tank's Purpose - ✔✔Stores the system's oil supply
✔✔Reservoir / Oil Tank Components - ✔✔Vent, Deaerator, Oil Level Transmitter,
Coarse Mesh Screens, Various oil and air inlets and outlets
✔✔Vent - ✔✔Controls air pressure in the tank to ensure a constant supply of oil to the
main oil pump
✔✔Deaerator - ✔✔Seperates air from oil returning to the oil tank
✔✔Oil Level Transmitter - ✔✔Can be a Dip Stick or Sight Gauge or even an actual
transmitter that send electrical signal to an oil level indicator in the cockpit
✔✔Coarse Mesh Screens - ✔✔Collects contaminants
✔✔Various oil and air inlets and outlets - ✔✔Holes
✔✔Lubrication System Valves - ✔✔Pressure Relief Valve, Check Valve, and Bypass
Valve
✔✔Pressure Relief Valve - ✔✔Limits maximum pressure where the valve opens, and
returns the excess oil to the inlet side of the pump
✔✔Check Valve - ✔✔Allows flow in one direction only
