PP 04

What is meant by density altitude?. The altitude corrected for wind and temperature. The altitude relative to the standard atmosphere conditions. The indicated altitude corrected for temperature. The altitude read directly from the altimeter.

Does exhaust back pressure increase or decrease as an aircraft increases in altitude?. It increases significantly. It remains constant. It decreases. It fluctuates randomly.

Why is tetraethyl lead added to aviation gasoline?. To improve engine lubrication. To increase the fuel’s octane rating. To lower freezing point. To reduce vapor pressure.

What color is 100/130-grade aviation gasoline?. Blue. Purple. Green. Red.

What color is 100LL-grade aviation gasoline?. Green. Blue. Purple. Yellow.

What color is 115/145-grade aviation gasoline?. Purple. Green. Blue. Red.

What device in a float carburetor provides the low pressure at the main discharge nozzle?. The venturi. The throttle plate. The fuel pump. The air bleed.

If a float carburetor has no air bleed, will the mixture become richer or leaner as the airflow volume through the engine increases?. Leaner. Richer. Unchanged. Depends on throttle setting.

If a float carburetor has an unrestricted air bleed, will the mixture ratio become richer or leaner as airflow increases?. Richer. Leaner. Constant. Slightly richer at idle only.

What are the two functions of the air bleed in a float carburetor?. To cool the venturi and balance pressure. To aid in fuel atomization and to provide better fuel distribution. To regulate idle and accelerate mixture. To stabilize float level and raise vaporization.

Would an obstruction to the inlet airflow to an aircraft float carburetor cause the mixture to become rich or lean?. Lean. Rich. Neutral. Erratic.

What is the correct air/fuel mixture ratio for an aircraft engine?. 8:1. 12:1. 16:1. 10:1.

How does the idle RPM of an engine equipped with a float carburetor controlled?. By adjusting the float level. By adjusting the idle stop which affects the position of the throttle valve. By changing the venturi size. By changing the air bleed jet.

When does the acceleration system of a float carburetor function?. During cruising. When the throttle is advanced. During shutdown. When the throttle is retarded.

What is another name for the power enrichment system in a float carburetor?. Boost pump. Economizer. Scavenger. Choke valve.

When carburetor controls are rigged, should the stop on the carburetor or in the cockpit be contacted first?. In the cockpit. At the carburetor. Either one. Mid-travel point.

What are two ways of controlling the mixture in a float carburetor?. dle jets and economizer. Venturi lever and float level. Back suction and variable orifice. Pressure diaphragm and fuel valve.

What will be the result if the float level in a carburetor is too low?. Too rich a mixture. Too lean a mixture. No effect on mixture. Engine will not idle.

Why is an accelerator pump installed on many float carburetors?. To prevent carb icing. To improve cold starts. For rapid acceleration to prevent fuel lag. To reduce fuel vaporization.

How is the float level adjusted in most aircraft carburetors?. Adjusting mixture screw. Changing venturi throat. Adding or removing washers under the needle and seat assembly. Bending float arms.

What would it mean if the butterfly valve on a float type carburetor had the number 18° stamped on it?. Maximum throttle angle is 18°. The valve is at an angle of 18 degrees when completely closed. The idle mixture setting is 18% rich. It opens 18° before fuel metering begins.

When the mixture screw on a float carburetor is adjusted, is mixture changed at cruise or only at idle?. Cruise only. Idle only. All throttle settings. High power only.

Is the fuel/air mixture measured by volume or by weight?. By volume. By weight. By temperature gradient. By density.

When does the main metering jet function in a carburetor?. Only during idle. At speeds above idle. During priming. Only during acceleration.

At what engine speed does the economizer provide the richest fuel/air mixture?. Idle. Cruise. Full power takeoff. Descent.

What pressure does chamber “A” sense in a pressure carburetor?. Venturi pressure. Impact pressure. Fuel pressure. Ambient pressure.

What pressure does chamber “B” sense in a pressure carburetor?. Venturi pressure. Fuel pressure. Impact pressure. Manifold pressure.

What pressure does chamber “D” sense in a pressure carburetor?. Metered fuel pressure. Unmetered fuel pressure. Impact pressure. Venturi pressure.

Why must a pressure carburetor be soaked before it is ready for flight?. To prevent ice. To saturate diaphragms so they become flexible. To prime fuel lines. To remove contaminants.

Does the idle speed adjustment valve on a pressure carburetor determine how much the throttle valve is held off its seat?. No. Yes. Only above 2000 RPM. Only at high altitude.

What type of fuel pressure is found in chamber “C” of a pressure carburetor?. Impact air pressure. Metered fuel pressure. Unmetered fuel pressure. Venturi air pressure.

What two forces in the Bendix RSA system make up the air metering force?. Fuel pressure and throttle position. Intake vacuum and mixture ratio. Impact pressure and venturi pressure. Exhaust velocity and throttle plate angle.

What two forces in the Bendix RSA system make up the fuel metering force?. Metered and unmetered fuel pressure. Venturi pressure and boost pump pressure. Injector nozzle pressure and fuel return. Throttle position and mixture cable.

Where is the flow divider normally located?. On the firewall. Beneath the oil sump. On top of the engine central to all cylinders. Behind the fuel pump.

What type of gage can the fuel/flow gage be classified as?. Temperature gage. Pressure gage. Level gage. Flow restriction gage.