Reciprocating Engines Flashcards
In what position should the crankshaft be when a magneto is being timed to the engine?
Piston in cylinder 1 is about 30 degrees before top dead center on the compression stroke
What is checked on engine runup to determine the operational condition of the engine?
- Idling RPM and manifold pressure
- Engine acceleration
- Maximum static RPM
- Magneto drop
- Ignition switch safety check
- Propeller pitch change
- Propeller feathering
- Oil pressure
- Fuel flow
What is hydraulic lock in an aircraft engine?
Oil has been drained past the piston rings and filled the combustion chamber of cylinders that are below the center line of the engine. If the crankshaft is turned over with this oil in the cylinder it will lock, and there is a probability that the piston, cylinder, or connecting rod will be damaged
How is hydraulic lock removed from an aircraft engine?
Remove a spark plug from the locked cylinder and drain all the oil out. Clean the spark plug and replace it
What are the four strokes of a 4-stroke reciprocating engine?
- Intake
- Compression
- Power
- Exhaust
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
- 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
- Oil scraper
Where should piston ring gaps be installed relative to each other and why?
Compression(???) ring gaps should be staggered so that they don’t align to 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
On engines equipped with hydraulic valve lifters, what should the running valve clearance be?
Zero
What is the purpose of valve overlap?
- Better volumetric efficiency
- 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 the cylinder
When pulling a propeller through, a hissing sound is heard, indicating a 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 its total time affected?
The total time on the engine must be continued and the time since major overhaul is entered into the engine log
What inspections should be performed after a propeller strike without sudden stoppage?
- Inspect engine mounts, the crankcase, and the nose section for damage
- Inspect the oil and oil filters/screen for metal particles
- Inspect the crankshaft or driveshaft for cracks and misalignment
Name some of the precautions that should be performed prior to engine removal
- Disconnect the battery
- Turn off the fuel valves
- Chock the wheels
- Install a tail stand
When inspecting a piston, where are cracks most likely to be found?
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”?
It means that the part is within the manufacturer’s limits and doesn’t need to be replaced
What tools or instruments are used to inspect a cylinder barrel for out-of-roundness?
A dial indicator or an inside micrometer
How can a loose stud in an engine crankcase be repaired?
Remove the loose stud and inspect the hole for size and thread condition
What publication is used to check an engine for normal operation?
Manufacturer’s maintenance manual
A weak cylinder is found during a compression check. What must be inspected?
The inside of a cylinder
What purpose does an oil analysis serve?
This helps in evaluating the engine’s internal condition. Metal particles in the oil show normal and abnormal wear of the engine
What inspection should be performed on an engine that has been in storage?
Perform an inspection to determine if there is any corrosion damage
Where would a carburetor air temperature bulb be located?
In the ram air intake duct
What is the fuel pressure range on float-type carburetors?
3 - 5 psi
Where is the fuel flow indicating system generally connected within a carbureted reciprocating engine?
Between the engine fuel pump and the carburetor
Name the basic components of a fuel flow system
- Transmitter
- Indicator
What unit of measure is generally used to indicate fuel flow?
Pounds or gallons per hour
Why is fuel flow monitored?
To determine fuel consumption and engine performance
What does the manifold gauge indicate and how is it calibrated?
It measures the absolute pressure in the engine manifold and is calibrated in inches of mercury
What directly controls manifold pressure?
Throttle opening and engine RPM
During engine operation, where should the propeller control be set when checking the manifold pressure?
Low pitch, high RPM
Is the aircraft electrical system required to power a cylinder head temperature gauge?
No. A thermocouple is used as the electrical source
What are the possible indications of an oil pressure transmitter or indicator malfunction?
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?
Engine RPM
Where should the thermocouple be installed on a reciprocating engine using a single probe cylinder head temperature system?
On the hottest cylinder
