Reciprocating engines Flashcards
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
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 of 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?
It allows better volumetric efficiency and lowers cylinder operating temperatures
When troubleshooting a running engine malfunction, what does a cold cylinder indicate?
No combustion in that cylinder
Name at least one part of an inspection that should be made after a propeller strike
1) Inspect the engine mounts, crankcase and nose section for damage
2) Inspect the oil screens/filters for metal particles
3) Inspect the propeller drive or crankshaft for misalignment
What is the fuel pressure range on float type carburetors?
3-5 psi
What publication is used to check an engine for normal operation?
The manufacturer’s maintenance manual
What should be done to repair a loose stud in an engine crankcase?
Remove the loose stud, inspect the hole for size and condition of the threads. It may be necessary to use a suitable oversized stud or heli-coil insert.
What is an indication that a primer is leaking or is open during engine operation?
The engine will not idle properly
What procedure should be followed when valve blow-by is indicated by a hissing sound on a reciprocating engine when pulling the propeller through?
Perform a cylinder compression test to identify the faulty cylinder
What factors about the condition of an engine can be learned by studying the results of a compression test?
The results of a compression test determine if the valves, piston rings and pistons are adequately sealing
What is meant when it is said that an engine part is within serviceable limits?
A part that is within the manufacturer’s serviceable limits and can be used in an engine, will not likely wear to the point of causing engine failure within the next time between overhaul TBO interval
When an engine is overhauled, how is its total time affected? When it is rebuilt, how is its operating history affected?
Overhauled- the total time on the engine must be continued and the time since major overhaul is entered into the logbook.
Rebuilt- if the manufacturer rebuilds the engine it is granted a zero time status and is considered to have no previous operating history.
Name some of the precautions that should be performed prior to engine replacement
Disconnect the battery, turn off the fuel valves, chock the wheels and install a tail stand if necessary
When inspecting a piston, where are cracks most likely to be found?
Highly stressed areas, base of piston bosses, inside at the junction of the bore and the walls and ring lands
What is the purpose of performing a compression test?
To determine if the valves, pistons and rings are sealing properly
What tools or instruments are used to inspect a cylinder barrel for out-of-roundness?
A dial indicator or an inside micrometer is usually used to measure the top of the cylinder at the skirt ( a telescopic gauge and micrometer can also be used). Two readings should be taken 90* to each other
