Chapter 1 - Reciprocating Engines - Oral Questions Flashcards
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.
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/screens 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, and if necessary, 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 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?
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?
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 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.
