RECIPROCATING AND TURBINE
POWERPLANT THEORY &
MAINTENANCE EXAM QUESTIONS AND
ANSWERS 2026 VERIFIED.
How are conventional reciprocating engines classified? - ANS They are classified according to
cylinder arrangement with respect to the crankshaft or method of cooling.
What are the different types of piston rings? - ANS Compression rings, oil control rings, and
scraper rings.
What is the purpose of the oil control rings? - ANS They are used to control the thickness of
the oil film on the cylinder walls.
What may be the result of installing piston rings incorrectly? - ANS Excessive oil consumption.
What type of piston rods are commonly found in radial engines? - ANS A master and
articulating rod assembly.
What type of bearings are in general use in reciprocating engines? - ANS Plain bearings,
Roller bearings, Ball bearings.
What is the indication of valve blow-by? - ANS A hissing or whistle when pulling the propeller
through prior to starting the engine.
@2026/2027 ALLRIGHTS RESERVED.
,What is the purpose of using more than one spring for valve closing? - ANS To eliminate valve
vibration or surge at certain speeds.
What is the purpose of valve overlap? - ANS To permit better volumetric efficiency and lower
cylinder operating temperatures.
What should be inspected on valve springs during engine overhaul? - ANS They should be
cleaned and visually inspected for overheating, cracks, and compression strength.
What is the purpose of using valves with sodium filled stems? - ANS To conduct heat from the
valve head to the stem and dissipate it.
What causes engine sudden stoppage? - ANS Striking an object or engine seizure due to
internal damage.
What should be inspected after a propeller strike? - ANS Inspect the engine mounts,
crankcase, and oil for metal particles.
What is the purpose of crankshaft dynamic dampers in aircraft engines? - ANS To overcome
forces causing deflection and torsional vibration.
How would you make a 'runout' check on a crankshaft? - ANS Attach a dial indicator gauge to
the crankcase and note changes in the gauge reading.
What is detonation? - ANS The instantaneous explosive burning of the last portion of the
fuel-air charge.
What can be learned from a compression check? - ANS It determines if the valves, piston
rings, and pistons are sealing the combustion chamber.
@2026/2027 ALLRIGHTS RESERVED.
, How can a cold cylinder be located on an engine? - ANS Using a cold cylinder indicator to find
cylinders with lower temperatures.
What instrument can check a cylinder bore for out of roundness? - ANS Dial indicator,
telescopic gauge, or inside micrometer.
What are the major components of a typical gas turbine engine? - ANS Air inlet, compression
section, combustion section, turbine section, exhaust section, and accessory section.
What are the two principal types of compressors used in turbojet aircraft? - ANS Centrifugal
flow and axial flow types.
What are the three types of combustion chamber systems? - ANS Can type, can-annular type,
and annular type.
What is the purpose of the interconnector tubes between can type combustion chambers? -
ANS To spread the flame to combustion chambers without igniter plugs during starting.
What prevents burning of the liner walls in can type combustion chambers? - ANS Louvers
direct a cooling layer of air along the inside wall of the liner.
What types of damage may be found when inspecting compressor blades? - ANS Dents,
scratches, gouges, burns, pitting, and cracks.
What is the location and function of the diffuser section in a turbine engine? - ANS It is
located between the compressor section and the burner cans, changing high velocity air to
static pressure.
Where are stress rupture cracks most likely to occur on turbine blades? - ANS They usually
appear as small hairline cracks on or across the leading or trailing edge.
@2026/2027 ALLRIGHTS RESERVED.
POWERPLANT THEORY &
MAINTENANCE EXAM QUESTIONS AND
ANSWERS 2026 VERIFIED.
How are conventional reciprocating engines classified? - ANS They are classified according to
cylinder arrangement with respect to the crankshaft or method of cooling.
What are the different types of piston rings? - ANS Compression rings, oil control rings, and
scraper rings.
What is the purpose of the oil control rings? - ANS They are used to control the thickness of
the oil film on the cylinder walls.
What may be the result of installing piston rings incorrectly? - ANS Excessive oil consumption.
What type of piston rods are commonly found in radial engines? - ANS A master and
articulating rod assembly.
What type of bearings are in general use in reciprocating engines? - ANS Plain bearings,
Roller bearings, Ball bearings.
What is the indication of valve blow-by? - ANS A hissing or whistle when pulling the propeller
through prior to starting the engine.
@2026/2027 ALLRIGHTS RESERVED.
,What is the purpose of using more than one spring for valve closing? - ANS To eliminate valve
vibration or surge at certain speeds.
What is the purpose of valve overlap? - ANS To permit better volumetric efficiency and lower
cylinder operating temperatures.
What should be inspected on valve springs during engine overhaul? - ANS They should be
cleaned and visually inspected for overheating, cracks, and compression strength.
What is the purpose of using valves with sodium filled stems? - ANS To conduct heat from the
valve head to the stem and dissipate it.
What causes engine sudden stoppage? - ANS Striking an object or engine seizure due to
internal damage.
What should be inspected after a propeller strike? - ANS Inspect the engine mounts,
crankcase, and oil for metal particles.
What is the purpose of crankshaft dynamic dampers in aircraft engines? - ANS To overcome
forces causing deflection and torsional vibration.
How would you make a 'runout' check on a crankshaft? - ANS Attach a dial indicator gauge to
the crankcase and note changes in the gauge reading.
What is detonation? - ANS The instantaneous explosive burning of the last portion of the
fuel-air charge.
What can be learned from a compression check? - ANS It determines if the valves, piston
rings, and pistons are sealing the combustion chamber.
@2026/2027 ALLRIGHTS RESERVED.
, How can a cold cylinder be located on an engine? - ANS Using a cold cylinder indicator to find
cylinders with lower temperatures.
What instrument can check a cylinder bore for out of roundness? - ANS Dial indicator,
telescopic gauge, or inside micrometer.
What are the major components of a typical gas turbine engine? - ANS Air inlet, compression
section, combustion section, turbine section, exhaust section, and accessory section.
What are the two principal types of compressors used in turbojet aircraft? - ANS Centrifugal
flow and axial flow types.
What are the three types of combustion chamber systems? - ANS Can type, can-annular type,
and annular type.
What is the purpose of the interconnector tubes between can type combustion chambers? -
ANS To spread the flame to combustion chambers without igniter plugs during starting.
What prevents burning of the liner walls in can type combustion chambers? - ANS Louvers
direct a cooling layer of air along the inside wall of the liner.
What types of damage may be found when inspecting compressor blades? - ANS Dents,
scratches, gouges, burns, pitting, and cracks.
What is the location and function of the diffuser section in a turbine engine? - ANS It is
located between the compressor section and the burner cans, changing high velocity air to
static pressure.
Where are stress rupture cracks most likely to occur on turbine blades? - ANS They usually
appear as small hairline cracks on or across the leading or trailing edge.
@2026/2027 ALLRIGHTS RESERVED.
