Chapter 5 -- Engine

The usual method of shutting an engine down is to: a. switch the magnetos off b. move the mixture to idle cut-off c. switch the master switch off

B

Why would you normally avoid using carburetor heat during ground operations?

Because the hot air source is unfiltered

What is the remedy for suspected carburetor ice?

Carburetor heat

What is the uncontrolled firing of the fuel/air charge in advance of normal spark ignition known as?

Preignition

If the oil quantity gauge suddenly drops to zero in flight, which gauge should you check immediately?

The oil temperature gauge

How are impurities in the oil removed?

With the oil filter

If a magneto ground wire comes loose in flight, will the engine stop?

no

Does the principle of leaning the mixture by reducing the fuel flow to match the lower density air as altitude is gained apply to fuel-injected engines?

yes

Hotter air entering the engine after carburetor heat is applied will be less dense, which means that less air by weight for the same weight of fuel enters the cylinders. Will applying carburetor heat therefore result in a richer mixture?

yes

If the engine is cold prior to start-up, it should be shut down if the oil pressure does not rise within how many seconds after start-up?

30 seconds

A de-tuning of engine crankshaft counterweights is a source of overstress that may be caused by: a. rapid opening and closing of the throddle b. carburetor ice forming on the throttle valve c. operating with an excessively rich fuel/air mixture

A

For takeoff at a sea level airport on a cool day, the mixture control should normally be: a. full rich b. lean c. in idle cut-off

A

With regard to carburetor ice, float-type carburetor systems in comparison to fuel injection systems are generally considered to be: a. more susceptible to icing b. Equally susceptible to icing c. susceptible to icing only when visible moisture is present

A

What is one of the first indications of carburetor ice forming in an airplane equipped with fixed-pitched propeller?

A loss of power (indicated by a decrease in RPM)

What carburetor device ensures that sufficient fuel is fed to the cylinders when idling at low RPM?

An idling jet

Excessively high engine temperatures will: a. cause damage to heat-conducting hoses and warping of the cylinder cooling fins b. cause loss of power, excessive oil consumption, and possible permanent internal engine damage c. not appreciably affect an aircraft engine

B

If a pilot suspects that the engine (with a fixed-pitch propeller) is detonating during climb-out after takeoff, the initial corrective action to take would be to: a. lean the mixture b. lower the nose slightly to increase air-speed c. apply carburetor heat

B

If the oil temperature gauge and the cylinder head temperature gauge are both reading higher than their normal operating range, a possible cause is: a. an over-rich mixture and too much power b. a too-lean mixture and too much power c. fuel with a higher-than-specified fuel rating

B

In an airplane with a constant-speed propeller, which of the following procedures should be used? a. when power is decreased, reduce RPM before manifold pressure b. when power is increased, increase RPM before manifold pressure c. when power is increased or decreased adjust manifold pressure before RPM

B

The spark plugs in a piston engine are provided with a high energy (or high tension) electrical supply from: a. the battery at all times b. the magnetos c. the battery at start-up, then the magnetos

B

When operating a constant-speed propeller: a. avoid high RPM setting with high manifold pressures b. avoid low RPM settings with high manifold pressures c. always use a rich mixture with high RPM settings

B

How is the fuel/ air mixture ignited in the cylinder?

By a high-voltage spark just prior to top-dead-center and the commencement of the power stroke

Because of the very low revs as you start the engine, the spark needs to be delayed. How is this done automatically in some magnetos?

By impulse coupling

How is detonation caused?

By using a lower than specified grade of fuel and/or excessively high engine temperatures. Detonation may also be caused by the mixture being too lean

As air density decreases, the weight of fuel introduced into the cylinder needs to be reduced to match the decreased weight of air. How is this done?

By using the mixture control, which is usually a red colored knob

For internal cooling, reciprocating aircraft engines are especially dependent on: a. a properly functioning thermostat b. air flowing over the exhaust manifold c. the circulation of lubricating oil

C

If no leaning is made with the mixture control as the flight altitude increases: a. the volume of air entering the carburetor decreases and the amount of fuel decreases b. the density of air entering the carburetor decreases and the amount of fuel increases c. the density of air entering the carburetor decreases and the amount of fuel remains constant.

C

If the ground wire between the magneto and the ignition switch becomes disconnected, the engine: a. will not operate on one magneto b. cannot be started with the switch in the BOTH position c. could accidentally start if the propeller is moved with fuel in the cylinder

C

The correct procedure to achieve the best fuel/air mixture when cruising at altitude is to move the mixture control toward LEAN until the engine RPM: a. drops to a minimum value b. reaches a peak value c. passes through a peak value at which point the mixture control is returned to a slightly richer position

C

The presence of carburetor ice in an aircraft equipped with a fixed-pitch propeller can be verified by applying carburetor heat and: a. noting an increase in RPM, then gradual decrease in RPM b. noting a decrease in RPM, then a constant RPM indication c. Noting a decrease in RPM, then a gradual increase in RPM

C

Which condition is most favorable to the development of carburetor icing? a. any temperature below freezing and relative humidity of less than 50 percent b. between 32 degrees F and 50 degrees F and low humidity c. between 20 degrees F and 70 degrees F and high humidity

C

How should you decrease power with a constant-speed propeller?

Decrease manifold pressure first, followed by RPM

What is detonation?

Detonation is an explosive combustion of the fuel/air mixture in the cylinders

What remains following combustion of a rich mixture?

Excess fuel

True or false? Oil grades may be mixed

False - oil grades may not be mixed

What can an over-rich mixture cause?

Fouling of the spark plugs

Explain your answer to question 71 and state why the other alternatives are incorrect.

In a carburetor engine, moving the mixture to idle cut-off clears the induction manifold and engine cylinders of fuel. With a fuel-injected engine, this clears fuel lines and cylinders of fuel. Not answer a - stopping the engine by removing the spark ignition would leave fuel in the fuel lines and engine. Not answer C -- this would only turn off aircraft electrical services such as lighting, or radios, but would have no effect at all on the engine or engine ignition.

How should you increase power with a constant-speed propeller?

Increase RPM first, then manifold pressure

Name the four strokes of a piston engine commencing with the stroke intake.

Intake (or induction), compression, power (or expansion), and exhaust

What does "leaning the mixture" mean?

It means reducing the amount of fuel to match the reduced weight of air

What is the effect of leaving the carburetor heat on while taking off?

It will increase the ground roll

Is the exhaust valve open during most of the compression stroke?

No

Is the intake valve open during most of the compression stroke?

No

Is the intake valve open during most of the exhaust stroke?

No

What is the function of oil?

Oil lowers friction between moving parts and so prevents high temperatures, and what heat is formed can to some extent be carried away by circulating oil

What should the pilot monitor when an engine is started up?

Oil pressure

When is the engine fuel primer used?

Only prior to startup

What are hot-spots in a combustion chamber likely to cause?

Preignition

What action can a pilot take to aid in cooling an engine that is overheating during a climb?

Reduce rate of climb and increase airspeed

How is carburetor ice formed?

The expansion of air as it accelerates through the carburetor venturi causes it to drop in temperature, and if it contains moisture carburetor ice can form

While cruising at 9,500 feet MSL, the fuel/air mixture is properly adjusted. What will occur if a descent to 4,500 feet MSL is made without readjusting the mixture?

The fuel/air mixture may become excessively lean

What is meant by the term best-power mixture?

The fuel/air ratio which provides the most power for any given throttle setting

Describe the principle of a simple carburetor

The principle of a simple carburetor is to decrease the pressure as air flows through a venturi throat and draw fuel into the passing airstream

What is the fuel/air ratio?

The ratio between the weight of the fuel and the weight of the air entering the carburetor

What is the most probable reason an engine continues to run after the ignition switch has been turned off?

There is a broken magneto ground wire

What is the function of cooling fins?

To increase the exposed surface area in order to allow better cooling

True or false? A constant-speed propeller, with cruise RPM selected, automatically adjusts its blade angle to absorb the power available

True

True or false? IF you are cruising at 8,000 feet MSL, you will achieve better fuel efficiency by leaning the mixture

True

True or false? Switching the ignition OFF connects the magneto systems to ground

True

True or false? The extra fuel in a rich mixture causes extra heating in the cylinders by its evaporation

True

True or false? The pressure drop (and consequent temperature drop) near the throttle butterfly is greatest at small throttle openings, causing a greater likelihood of carburetor ice forming

True

True or false? a fixed-pitch propeller achieves its best efficiency at only one airspeed and RPM

True

True or false? dirty and contaminated oil is better than no oil at all.

True

What is the period when both intake and exhaust valves are open simultaneously known as?

Valve overlap

How does the pilot control the fuel/air ratio?

With the mixture control

If one of the magneto switches is turned to OFF, should there be an engine RPM drop?

Yes

Is the exhaust valve open during most of the exhaust stroke?

Yes

Prior to takeoff, should you check each of the two ignition systems with a magneto check?

Yes

What might you observe with too little oil?

You may observe a high oil temperature and/or a low oil pressure

How is power indicated: a. for a fixed-pitch propeller? b. for an engine equipped with a constant speed propeller?

a. RPM b. Manifold pressure and RPM

As altitude is gained when climbing in an airplane equipped with a constant-speed propeller: a. what will happen to the RPM b. what will happen to the manifold pressure unless you adjust the throttle?

a. RPM will stay the same b. MP will decrease by about 1 in. Hg per 1,000 feet

For an engine equipped with a constant-speed propeller: a. what is fuel flow and consequently power output controlled by? b. what is the power output registered on?

a. the throttle b. the manifold pressure gauge

The oil temperature gauge shows a rapid increase in temperature. a. what should you suspect? b. what actions should you consider?

a. you should suspect a serious loss of oil b. you should consider an immediate landing

What remains following combustion of a lean mixture?

excess air

If the oil filter becomes blocked, what happens to the unfiltered oil?

it is forced through an oil filter bypass valve