BAKERS ORAL POWERPLANT ACTUAL
TEST PAPER QUESTIONS AND SOLUTIONS
VERIFIED COMPLETE ANSWERS
●● what are the different types of piston rings
Answer: compression rings, oil control rings and scraper rings
●● what are the main causes of a cylinder having low compression
Answer: broken piston rings, rings that are not seated properly, burnt
valves and poorly seating valves
●● what is the purpose of the oil control rings?
Answer: 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
Answer: excessive oil consumption
●● what type of piston rods are commonly found in radial engines
Answer: a master and articulating rod assembly
●● what type of bearings are in general use in reciprocating engines
,Answer: plain, roller and ball bearings
●● what is the indication of valve blowby
Answer: a hissing or whistle when pulling the propeller through by hand
●● what is the purpose of using more than one spring for valve closing
Answer: valve springs will resonate (or surge) at certain engine speeds.
●● what is the purpose of valve overlap
Answer: better volumetric efficiency and lowers the cylinder operating
temperatures
●● describe the inspection you would give the valve springs during
engine overhaul
Answer: they should be cleaned thoroughly, then visually inspected for
evidence of overheating, cracks, broken ends, and compression strengh
●● what is the purpose of using valves with sodium filled stems
Answer: because it is an excellent heat conductor
●● what causes engine sudden stoppage
Answer: Striking an object or engine seizure due to internal damage.
,●● What type inspection must be made after sudden stoppage of an
engine?
Answer: a complete engine tear down and inspection
●● what is the purpose of the crankshaft dynamic dampers used in
aircraft engines
Answer: to overcome forces which cause deflection of the crankshaft
and torsional vibration
●● How would you make a "runout" check on a crankshaft that is still
installed in the engine?
Answer: remove the propeller from the crankshaft and attach a dial
indicator gauge to the front of the crankcase. adjust the position of the
gauge needle so that it is touching the shaft. rotate the crankshaft and
check for misalignment
●● what is detonation?
Answer: The instantaneous explosive burning of the last portion of the
charge
●● what cylinder is engine to magneto timing based on?
Answer: the number one cylinder
●● what is engine sudden speed reduction
, Answer: This occurs when the propeller strikes an object but continues
to run.
●● What can be learned about the condition of an engine by studying the
results of a compression check?
Answer: if the valves, piston rings, and pistons are adequately sealing
the combustion chamber
●● How can a cold cylinder be located on a double row radial engine?
Answer: with a cold cylinder indicator, sometimes called a "magic
wand"
●● what instrument can be used to check bore for out of roundness
Answer: a dial indicator, telescopic gauge and outside micrometer or
inside mircrometer
●● what would a cold cylinder indicate
Answer: no combustion inside the cylinder
●● where is a crack most likely to occur on a piston
Answer: where the piston pin/wrist pin connects
●● what should be done to a nose wheel airplane before removing the
engine
TEST PAPER QUESTIONS AND SOLUTIONS
VERIFIED COMPLETE ANSWERS
●● what are the different types of piston rings
Answer: compression rings, oil control rings and scraper rings
●● what are the main causes of a cylinder having low compression
Answer: broken piston rings, rings that are not seated properly, burnt
valves and poorly seating valves
●● what is the purpose of the oil control rings?
Answer: 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
Answer: excessive oil consumption
●● what type of piston rods are commonly found in radial engines
Answer: a master and articulating rod assembly
●● what type of bearings are in general use in reciprocating engines
,Answer: plain, roller and ball bearings
●● what is the indication of valve blowby
Answer: a hissing or whistle when pulling the propeller through by hand
●● what is the purpose of using more than one spring for valve closing
Answer: valve springs will resonate (or surge) at certain engine speeds.
●● what is the purpose of valve overlap
Answer: better volumetric efficiency and lowers the cylinder operating
temperatures
●● describe the inspection you would give the valve springs during
engine overhaul
Answer: they should be cleaned thoroughly, then visually inspected for
evidence of overheating, cracks, broken ends, and compression strengh
●● what is the purpose of using valves with sodium filled stems
Answer: because it is an excellent heat conductor
●● what causes engine sudden stoppage
Answer: Striking an object or engine seizure due to internal damage.
,●● What type inspection must be made after sudden stoppage of an
engine?
Answer: a complete engine tear down and inspection
●● what is the purpose of the crankshaft dynamic dampers used in
aircraft engines
Answer: to overcome forces which cause deflection of the crankshaft
and torsional vibration
●● How would you make a "runout" check on a crankshaft that is still
installed in the engine?
Answer: remove the propeller from the crankshaft and attach a dial
indicator gauge to the front of the crankcase. adjust the position of the
gauge needle so that it is touching the shaft. rotate the crankshaft and
check for misalignment
●● what is detonation?
Answer: The instantaneous explosive burning of the last portion of the
charge
●● what cylinder is engine to magneto timing based on?
Answer: the number one cylinder
●● what is engine sudden speed reduction
, Answer: This occurs when the propeller strikes an object but continues
to run.
●● What can be learned about the condition of an engine by studying the
results of a compression check?
Answer: if the valves, piston rings, and pistons are adequately sealing
the combustion chamber
●● How can a cold cylinder be located on a double row radial engine?
Answer: with a cold cylinder indicator, sometimes called a "magic
wand"
●● what instrument can be used to check bore for out of roundness
Answer: a dial indicator, telescopic gauge and outside micrometer or
inside mircrometer
●● what would a cold cylinder indicate
Answer: no combustion inside the cylinder
●● where is a crack most likely to occur on a piston
Answer: where the piston pin/wrist pin connects
●● what should be done to a nose wheel airplane before removing the
engine
