A&P - Aircraft and Powerplant Reciprocating Engine Overhaul Questions and Answers — Questions and Answers
Question 1: Which of the following defines a "major overhaul" of a reciprocating engine according to FAA guidance?
- The repair of components outside the crankcase, which may include cylinder removal and piston ring replacement.
- The complete disassembly, inspection, repair as necessary, reassembly, and testing of an engine to the manufacturer's specified fits and limits. (Correct answer)
- Any repair that, if improperly done, might appreciably affect weight, balance, structural strength, performance, or other qualities affecting airworthiness.
- An engine that has been disassembled, cleaned, inspected, and approved for return to service using only new parts.
Correct answer: The complete disassembly, inspection, repair as necessary, reassembly, and testing of an engine to the manufacturer's specified fits and limits.
A major overhaul consists of the complete disassembly of an engine, followed by inspection, repair as necessary, reassembly, testing, and approval for return to service within the manufacturer's specified fits and limits, which can be new or serviceable limits.
Question 2: During a reciprocating engine overhaul, a crankshaft's runout is measured using a dial indicator. The total indicated runout exceeds the manufacturer's specified limits. What is the correct course of action?
- The crankshaft can be straightened using an approved cold-working process.
- The crankshaft must be replaced. (Correct answer)
- The crankshaft can be re-used if the runout is within serviceable limits, even if it exceeds new limits.
- The engine can be reassembled and tested; runout may decrease during the break-in period.
Correct answer: The crankshaft must be replaced.
If a crankshaft's runout check reveals it is beyond the manufacturer's specified limits, it must be replaced. This is a critical check performed early in the overhaul process to resolve any questions about the crankshaft's serviceability.
Question 3: A technician is installing new piston rings on a piston during an engine overhaul. Which of the following is a critical step to ensure proper sealing and oil control?
- Aligning the end gaps of all compression and oil control rings to facilitate lubrication.
- Installing compression rings with the marked side facing down towards the piston skirt.
- Staggering the end gaps of the piston rings around the piston. (Correct answer)
- Using chrome-plated rings on a chrome-plated cylinder wall to maximize durability.
Correct answer: Staggering the end gaps of the piston rings around the piston.
It is critical to stagger the end gaps of the piston rings to prevent a direct path for combustion gases to blow by the piston or for oil to enter the combustion chamber. Aligning the gaps would compromise both compression and oil control.
Question 4: After performing a major overhaul on a reciprocating engine, what is the status of the engine's total time in service (TTIS)?
- The total time in service is reset to zero.
- The total time in service is cut in half.
- The total time in service continues from where it was before the overhaul. (Correct answer)
- A new logbook is started, and the previous time is archived.
Correct answer: The total time in service continues from where it was before the overhaul.
When a major overhaul is performed to either new or serviceable limits, the total time on the engine continues in the engine records. The time since major overhaul (TSMO) is reset to zero, but the total time accumulates. Only an engine 'rebuilt' by the manufacturer or an approved agency can be granted a zero-time status.
Question 5: An aircraft reciprocating engine has undergone a 'top overhaul.' Which of the following tasks would typically be included in this procedure?
- Splitting the crankcase to inspect the crankshaft and connecting rods.
- Removing and reconditioning the cylinders, pistons, and valve-operating mechanisms. (Correct answer)
- Overhauling the engine-driven accessories such as magnetos and the carburetor.
- Performing a dimensional inspection of the camshaft lobes for wear.
Correct answer: Removing and reconditioning the cylinders, pistons, and valve-operating mechanisms.
A top overhaul involves work on the parts on top of the crankcase without completely disassembling the engine. This typically includes removing cylinders for reconditioning, replacing or reconditioning pistons and rings, and servicing the valve-operating mechanism.
Question 6: During the dimensional inspection phase of an engine overhaul, a part is found to be worn but still within the 'serviceable limits' specified in the manufacturer's overhaul manual. What does this indicate?
- The part must be replaced with a new one.
- The part can be legally reinstalled and is expected to last until the next TBO. (Correct answer)
- The part requires a major repair before it can be used.
- The part can only be used if the engine is being reassembled for non-certified, experimental use.
Correct answer: The part can be legally reinstalled and is expected to last until the next TBO.
If a part conforms to the 'serviceable' fits and limits specifications listed in the manufacturer's overhaul manual, it is considered airworthy and can be reinstalled in the engine. These limits are established by the manufacturer to ensure the part will function reliably for its intended service life.
A&P - Aircraft and Powerplant Reciprocating Engine Overhaul Questions and Answers
Which of the following defines a "major overhaul" of a reciprocating engine according to FAA guidance?