(A&P - Powerplant Oral (Jeppesen): 2026 Questions and Answers)
What is the purpose of dynamic dampers on crankshafts?
They reduce engine vibration.
What types of bearings are generally found in reciprocating engines?
Plain, ball and roller bearings.
Are the connecting rods used in each cylinder of a radial engine the same? Explain.
No. Radial engines use master and articulating rod assemblies.
Name the different types of piston rings.
Oil control, compression, and oil scraper.
3/30/2026, 5:31:26 PM 3/30/2026, 5:31:25 PM 3/30/2026, 5:31:22 PM
, (A&P - Powerplant Oral (Jeppesen): 2026 Questions and Answers)
Where should piston ring gaps be installed relative to each other, and why?
Compression ring gaps should be staggered so that they do not align. This prevents excessive
blow-by.
What could result from incorrectly installed piston rings?
Excessive oil consumption.
What purpose do oil control rings serve?
They regulate the thickness of the oil film on the cylinder walls.
What is used to help prevent valve surge or floating in an aircraft engine?
Two or more springs are used on each valve.
3/30/2026, 5:31:26 PM 3/30/2026, 5:31:25 PM 3/30/2026, 5:31:22 PM
, (A&P - Powerplant Oral (Jeppesen): 2026 Questions and Answers)
On engines equipped with hydraulic valve lifters, what should the running valve clearance be?
Zero.
What is the purpose of valve overlap?
It allows better volumetric efficiency and lowers cylinder operating temperatures
What indications are given in the event of a leaking or open primer while the engine is running?
The engine will not idle properly.
A cold cylinder is found when troubleshooting a running engine. What does this indicate?
No combustion in that cylinder.
3/30/2026, 5:31:26 PM 3/30/2026, 5:31:25 PM 3/30/2026, 5:31:22 PM
, (A&P - Powerplant Oral (Jeppesen): 2026 Questions and Answers)
When pulling a propeller through, a hissing sound is heard, indicating valve blow-by. What
procedure should be performed next?
A compression check should be performed to identify the faulty cylinder.
What is the purpose of performing a compression test?
To determine if the valves, pistons, and rings are sealing properly
When an engine is overhauled, how is the total time affected? When an engine is rebuilt, how is its
operating history affected?
The total time on the engine must be continued and the time since major overhaul is entered into
the engine log. It the manufacturer rebuilds the engine, it is granted a zero-time status and is
considered to have no previous operating history.
3/30/2026, 5:31:26 PM 3/30/2026, 5:31:25 PM 3/30/2026, 5:31:22 PM
What is the purpose of dynamic dampers on crankshafts?
They reduce engine vibration.
What types of bearings are generally found in reciprocating engines?
Plain, ball and roller bearings.
Are the connecting rods used in each cylinder of a radial engine the same? Explain.
No. Radial engines use master and articulating rod assemblies.
Name the different types of piston rings.
Oil control, compression, and oil scraper.
3/30/2026, 5:31:26 PM 3/30/2026, 5:31:25 PM 3/30/2026, 5:31:22 PM
, (A&P - Powerplant Oral (Jeppesen): 2026 Questions and Answers)
Where should piston ring gaps be installed relative to each other, and why?
Compression ring gaps should be staggered so that they do not align. This prevents excessive
blow-by.
What could result from incorrectly installed piston rings?
Excessive oil consumption.
What purpose do oil control rings serve?
They regulate the thickness of the oil film on the cylinder walls.
What is used to help prevent valve surge or floating in an aircraft engine?
Two or more springs are used on each valve.
3/30/2026, 5:31:26 PM 3/30/2026, 5:31:25 PM 3/30/2026, 5:31:22 PM
, (A&P - Powerplant Oral (Jeppesen): 2026 Questions and Answers)
On engines equipped with hydraulic valve lifters, what should the running valve clearance be?
Zero.
What is the purpose of valve overlap?
It allows better volumetric efficiency and lowers cylinder operating temperatures
What indications are given in the event of a leaking or open primer while the engine is running?
The engine will not idle properly.
A cold cylinder is found when troubleshooting a running engine. What does this indicate?
No combustion in that cylinder.
3/30/2026, 5:31:26 PM 3/30/2026, 5:31:25 PM 3/30/2026, 5:31:22 PM
, (A&P - Powerplant Oral (Jeppesen): 2026 Questions and Answers)
When pulling a propeller through, a hissing sound is heard, indicating valve blow-by. What
procedure should be performed next?
A compression check should be performed to identify the faulty cylinder.
What is the purpose of performing a compression test?
To determine if the valves, pistons, and rings are sealing properly
When an engine is overhauled, how is the total time affected? When an engine is rebuilt, how is its
operating history affected?
The total time on the engine must be continued and the time since major overhaul is entered into
the engine log. It the manufacturer rebuilds the engine, it is granted a zero-time status and is
considered to have no previous operating history.
3/30/2026, 5:31:26 PM 3/30/2026, 5:31:25 PM 3/30/2026, 5:31:22 PM
