ACS Powerplant Systems & Engine Overhaul 2

Question 1

During engine overhaul, what is the primary purpose of magnaflux inspection?

Accepted Answer

Detect surface and subsurface cracks in ferrous metal parts

Answer

Magnaflux (magnetic particle inspection) detects surface and subsurface cracks in ferrous metal parts by revealing disruptions in magnetic flux lines.

Question 2

What does the term 'dry tappet clearance' refer to in reciprocating engine maintenance?

Accepted Answer

Valve clearance measured with the engine cold and hydraulic lifters collapsed

Answer

Dry tappet clearance is the valve clearance measured with the engine cold and hydraulic lifters fully collapsed, used to verify proper valve train geometry.

Question 3

Which type of engine oil system is most commonly used in modern horizontally opposed aircraft engines?

Accepted Answer

Wet sump

Answer

Most horizontally opposed aircraft engines use a wet sump system where oil is stored in a sump at the bottom of the crankcase.

Question 4

What is the purpose of a compensating port in an aircraft engine fuel injection system?

Accepted Answer

To meter air reference pressure so fuel flow remains consistent with changes in throttle position

Answer

The compensating port references throttle body air pressure so the fuel injector's differential pressure accurately reflects engine airflow regardless of throttle position.

Question 5

During a top overhaul, a technician finds chrome cylinder walls. What special consideration applies?

Accepted Answer

Chrome cylinders must use cast iron piston rings, not chrome rings

Answer

Chrome-plated cylinders must be fitted with cast iron piston rings because two chrome surfaces together will not seat properly and will cause excessive wear.

(ACS) Airman Certification Standard Certified Mechanic Practice Test

(ACS) Airman Certification Standard Certified Mechanic Practice Test

ACS Powerplant Systems & Engine Overhaul 2