A&P - Powerplant Oral (Jeppesen) Exam Questions and Answers
What is the purpose of dynamic dampers on crankshafts? - Answer- They reduce engine vibration.
What types of bearings are generally found in reciprocating engines? - Answer- Plain, ball and roller bearings.
Are the connecting rods used in each cylinder of a radial engine the same? Explain. - Answer- No. Radial engines use master and articulating rod assemblies.
Name the different types of piston rings. - Answer- Oil control, compression, and oil scraper.
Where should piston ring gaps be installed relative to each other, and why? - Answer- 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? - Answer- Excessive oil consumption.
What purpose do oil control rings serve? - Answer- 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? - Answer- Two or more springs are used on each valve.
On engines equipped with hydraulic valve lifters, what should the running valve clearance be? - Answer- Zero.
What is the purpose of valve overlap? - Answer- 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? - Answer- The engine will not idle properly.
A cold cylinder is found when troubleshooting a running engine. What does this indicate? - Answer- No combustion in that cylinder. When pulling a propeller through, a hissing sound is heard, indicating valve blow-by. What procedure should be performed next? - Answer- A compression check should be performed to identify the faulty cylinder.
What is the purpose of performing a compression test? - Answer- 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? - Answer- 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.
What inspections should be performed after a propeller strike without sudden stoppage?
- Answer- 1.Inspect engine mounts, the crankcase, and the nose section for damage. 2.Inspect the oil and oil filters/screens for metal particles. 3.Inspect the crankshaft or driveshaft for cracks and misalignment.
Name some of the precautions that should be performed prior to engine removal. - Answer- Disconnect the battery, turn off the fuel valves, chock the wheels, and if necessary, install a tail stand.
When inspecting a piston, where are cracks most likely to be found? - Answer- In those areas that are highly stressed; usually the base of the piston bosses, inside at the junction of the bore and the walls, and the ring lands.
What does it mean if an engine part is within "serviceable limits"? - Answer- It means that the part is within the manufacturer's limits and can be used in an engine (does not require replacement).
What tools or instruments are used to inspect a cylinder barrel for out-of-roundness? - Answer- A dial indicator or an inside micrometer is usually used to measure the top of the cylinder and at the skirt. A telescopic gauge and micrometer can also be used. Two readings should be taken 90# to each other.
How can a loose stud in an engine crankcase be repaired? - Answer- Remove the loose
stud and inspect the hole for size and thread condition. It may be necessary to use an oversize stud or Heli-Coil.
What publication is used to check an engine for normal operation? - Answer- Manufacturer's maintenance manual.
A weak cylinder is found during a compression check. What must be inspected? - Answer- The inside of the cylinder. What purpose does an oil analysis serve? - Answer- Metal particles in the oil show normal and abnormal wear of the engine. This helps in evaluating the engine's internal condition.
What inspections should be performed on an engine that has been in storage? - Answer- Perform an inspection to determine if there is any corrosion damage.
Where would a carburetor air temperature bulb be located? - Answer- In the ram air intake duct.
What is the fuel pressure range on float-type carburetors? - Answer- 3 to 5 psi.
Where is the fuel flow indicating system generally connected within a carbureted reciprocating engine? - Answer- Between the engine fuel pump and the indicator.
Name the basic components of a fuel flow system. - Answer- The transmitter and the indicator.
What unit of measure is generally used to indicate fuel flow? - Answer- Pounds or gallons per hour.
Why is fuel flow monitored? - Answer- To determine fuel consumption and engine performance.
What does the manifold gauge indicate and how is it calibrated? - Answer- It measures the absolute pressure in the engine manifold and is calibrated in inches of mercury.
What directly controls manifold pressure? - Answer- Throttle opening and engine rpm.
During engine operation, where should the propeller control be set when checking the manifold pressure? - Answer- Low pitch, high r.p.m.
Is the aircraft electrical system required to power a cylinder head temperature gauge? - Answer- No. A thermocouple is used as the electrical source.
What are the possible indications of an oil pressure transmitter or indicator malfunction?
- Answer- A severe or sudden drop in oil pressure while the oil temperature remains normal and the oil supply remains full.
What does a tachometer indicate on a reciprocating engine? - Answer- Engine r.p.m.
Where should the thermocouple be installed on a reciprocating engine using a single probe cylinder head temperature system? - Answer- On the hottest cylinder
What is the purpose of dynamic dampers on crankshafts? - Answer- They reduce engine vibration.
What types of bearings are generally found in reciprocating engines? - Answer- Plain, ball and roller bearings.
Are the connecting rods used in each cylinder of a radial engine the same? Explain. - Answer- No. Radial engines use master and articulating rod assemblies.
Name the different types of piston rings. - Answer- Oil control, compression, and oil scraper.
Where should piston ring gaps be installed relative to each other, and why? - Answer- 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? - Answer- Excessive oil consumption.
What purpose do oil control rings serve? - Answer- 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? - Answer- Two or more springs are used on each valve.
On engines equipped with hydraulic valve lifters, what should the running valve clearance be? - Answer- Zero.
What is the purpose of valve overlap? - Answer- 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? - Answer- The engine will not idle properly.
A cold cylinder is found when troubleshooting a running engine. What does this indicate? - Answer- No combustion in that cylinder. When pulling a propeller through, a hissing sound is heard, indicating valve blow-by. What procedure should be performed next? - Answer- A compression check should be performed to identify the faulty cylinder.
What is the purpose of performing a compression test? - Answer- 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? - Answer- 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.
What inspections should be performed after a propeller strike without sudden stoppage?
- Answer- 1.Inspect engine mounts, the crankcase, and the nose section for damage. 2.Inspect the oil and oil filters/screens for metal particles. 3.Inspect the crankshaft or driveshaft for cracks and misalignment.
Name some of the precautions that should be performed prior to engine removal. - Answer- Disconnect the battery, turn off the fuel valves, chock the wheels, and if necessary, install a tail stand.
When inspecting a piston, where are cracks most likely to be found? - Answer- In those areas that are highly stressed; usually the base of the piston bosses, inside at the junction of the bore and the walls, and the ring lands.
What does it mean if an engine part is within "serviceable limits"? - Answer- It means that the part is within the manufacturer's limits and can be used in an engine (does not require replacement).
What tools or instruments are used to inspect a cylinder barrel for out-of-roundness? - Answer- A dial indicator or an inside micrometer is usually used to measure the top of the cylinder and at the skirt. A telescopic gauge and micrometer can also be used. Two readings should be taken 90# to each other.
How can a loose stud in an engine crankcase be repaired? - Answer- Remove the loose
stud and inspect the hole for size and thread condition. It may be necessary to use an oversize stud or Heli-Coil.
What publication is used to check an engine for normal operation? - Answer- Manufacturer's maintenance manual.
A weak cylinder is found during a compression check. What must be inspected? - Answer- The inside of the cylinder. What purpose does an oil analysis serve? - Answer- Metal particles in the oil show normal and abnormal wear of the engine. This helps in evaluating the engine's internal condition.
What inspections should be performed on an engine that has been in storage? - Answer- Perform an inspection to determine if there is any corrosion damage.
Where would a carburetor air temperature bulb be located? - Answer- In the ram air intake duct.
What is the fuel pressure range on float-type carburetors? - Answer- 3 to 5 psi.
Where is the fuel flow indicating system generally connected within a carbureted reciprocating engine? - Answer- Between the engine fuel pump and the indicator.
Name the basic components of a fuel flow system. - Answer- The transmitter and the indicator.
What unit of measure is generally used to indicate fuel flow? - Answer- Pounds or gallons per hour.
Why is fuel flow monitored? - Answer- To determine fuel consumption and engine performance.
What does the manifold gauge indicate and how is it calibrated? - Answer- It measures the absolute pressure in the engine manifold and is calibrated in inches of mercury.
What directly controls manifold pressure? - Answer- Throttle opening and engine rpm.
During engine operation, where should the propeller control be set when checking the manifold pressure? - Answer- Low pitch, high r.p.m.
Is the aircraft electrical system required to power a cylinder head temperature gauge? - Answer- No. A thermocouple is used as the electrical source.
What are the possible indications of an oil pressure transmitter or indicator malfunction?
- Answer- A severe or sudden drop in oil pressure while the oil temperature remains normal and the oil supply remains full.
What does a tachometer indicate on a reciprocating engine? - Answer- Engine r.p.m.
Where should the thermocouple be installed on a reciprocating engine using a single probe cylinder head temperature system? - Answer- On the hottest cylinder
