PP 07

What is the purpose of the resistor in a spark plug?. Raise peak voltage. Improve cylinder airflow. Reduce spark duration and increase plug life. Produce dual ignition.

What causes carbon fouling of a spark plug?. Lean mixture. Rich mixture. High RPM operation. Magneto over-timing.

What causes oil fouling of a spark plug?. Worn piston rings or valve guides. Poor fuel quality. Weak capacitor. Plug temperature too low.

If one spark plug misfires, what happens to CHT?. Rises. Falls. Stays constant. Oscillates.

What are two types of compression tests for aircraft engines?. Cold and hot test. High and low pressure. Direct reading and differential pressure. Static and dynamic.

How much pressure is used for a differential compression test?. 10 PSI. 60 PSI. 80 PSI. 100 PSI.

How much leakage is generally acceptable before considered excessive?. 5%. 15%. 25%. 40%.

When mixture control moved to idle cutoff, what should happen to RPM and manifold pressure if properly set?. RPM drops 100 immediately and MAP rises. RPM increases 25–50, then drops; MAP decreases slightly then rises. RPM remains constant until shutdown. RPM drops slowly, MAP unchanged.

What is backfiring usually caused by?. Too rich mixture. Water in fuel. Too lean mixture. Excessive timing advance.

What is after-firing usually caused by?. Too lean mixture. Too rich mixture. Spark plug arcing. Worn piston rings.

If red or orange flame seen from exhaust stacks at night, is mixture rich or lean?. Lean. Rich. Neutral. Depends on throttle.

If aircraft backfires and runs rough in flight but normal on ground, what likely problem?. Carburetor ice. Spark plug fouling. Worn piston rings. Vapor lock.

What probable cause of low compression during differential test if hissing heard at crankcase breather?. Worn valves. Worn piston rings. Loose spark plugs. Improper timing.

Which engine is more prone to detonation: high or low compression?. Low compression. Both equal. High compression. Depends on spark plug reach.

What should be done to a radial engine before starting to ensure hydraulic lock will not occur?. Add oil to cylinders. Drain fuel lines. Pull the prop through in normal direction by hand (mags off). Heat the oil sump.

What type of repair is used for a crankcase stud hole whose threads have been stripped out?. Replace the crankcase. Drill and tap to larger size. Install a Heli-coil. Fill with epoxy.

Excessive carbon deposits on the stem of a valve could cause what kind of problem?. Valve overheating. Valve sticking. Increased compression. Fuel starvation.

What two dimensional tests are used to determine the condition of a connecting rod?. Hardness and corrosion tests. Weight and angle checks. Straightness and alignment. Cylindrical bore and taper.

Why should the hydraulic plunger assembly in a hydraulic valve lifter never be magnetized?. It reduces lubrication effectiveness. It will interfere with crankcase pressure. Metal particles in oil may stick to the check valve. It increases valve lash.

At which stroke should the piston of a cylinder be placed before adjusting valve clearances?. End of intake stroke. Top of exhaust stroke. End of compression stroke. Mid-power stroke.

During a run-up, an unusual amount of smoke is coming from the engine breather tube. What does this indicate?. Lean mixture. Intake valve leaking. Worn piston rings causing blow-by. Improper magneto timing.

What kind of oil is used for the first 50 hours after an engine has been overhauled?. Synthetic oil. Mineral oil. Straight mineral oil. Multi-grade ashless dispersant oil.

What color will desiccant dryer plugs be if fully saturated with moisture?. Blue. Yellow. Brown. White.

What can be done to small cracks found in the cylinder fin area?. Replace the cylinder. Weld and heat treat. Stop drill them. Grind them smooth.

What is the total fin area that can normally be removed from a cylinder?. 5%. 10%. 15%. 25%.

What does QECA stand for?. Quick Engine Component Assembly. Qualified Engine Core Assembly. Quick Engine Change Assembly. Quick Exhaust Change Adapter.

What method of non-destructive testing is used for non-ferrous metal parts?. Magnetic particle. X-ray. Liquid penetrant or eddy current. Ultrasonic only.

At what air pressure should an engine be stored when placed in a sealed container?. 1 PSI. 3 PSI. 5 PSI. 7 PSI.

What is the minimum pressure a sealed engine storage container may drop to before re-preservation is required?. 0 PSI. 0.5 PSI. 1 PSI. 2 PSI.

What must be done every 30 days to an engine stored in a wooden container?. Rotate the crankshaft. Check the desiccant dryers. Add new preservative oil. Bleed the fuel system.

What position should the piston be when the cylinder is sprayed with rust-preventing compound?. Top Dead Center. Mid-stroke. Bottom center. Full intake position.

What color is the propeller control knob in the cockpit?. Red. Black. Blue. Green.

What must be checked when an engine is kept in storage for more than 30 days?. Cylinder compression. Desiccant dryers. Spark plug condition. Oil filter debris.

Why should you not rotate the crankshaft of an engine that has been preserved?. Prevent static discharge. To avoid damaging piston rings. To prevent breaking the seal of the rust-preventing compound. To avoid hydraulic lock.

Why should a paper filter element be cut apart during a 100-hour inspection?. To compare filter brands. To neutralize static charge. So it can be inspected for oil contamination. To measure filter wear.

What type of welding is used to repair a cracked crankcase?. TIG welding. MIG welding. Oxy-acetylene welding. Spot welding.