Operation Of Systems - B: System & Equipment Malfunctions

Question 1

What causes carburetor icing, and what are the first indications of its presence?

Answer 1

The vaporization of fuel, combined with the expansion of air as it passes through the carburetor, causes a sudden cooling of the mixture. The temperature of the air passing through the carburetor may drop as much as 60°F within a fraction of a second. Water vapor is squeezed out by this cooling, and if the temperature in the carburetor reaches 32°F or below, the moisture will be deposited as frost or ice inside the carburetor. For airplanes with a fixed-pitch propeller, the first indication of carburetor icing is loss of RPM. For airplanes with controllable-pitch (constant- speed) propellers, the first indication is usually a drop in manifold pressure.

Question 2

What method is used to determine that carburetor ice has been eliminated?

Answer 2

When heat is first applied, there will be a drop in RPM in airplanes equipped with a fixed-pitch propeller; there will be a drop in manifold pressure in airplanes equipped with a controllable-pitch propeller. If ice is present there will be a rise in RPM or manifold pressure after the initial drop (often accompanied by intermittent engine roughness); and then, when the carburetor heat is turned “off,” the RPM or manifold pressure will rise to a setting greater than that before application of heat. The engine should run more smoothly after the ice has been removed.

Question 3

What conditions are favorable for carburetor icing?

Answer 3

Carburetor ice is most likely to occur when temperatures are below 70°F (21°C) and the relative humidity is above 80 percent. However, due to the sudden cooling that takes place in the carburetor, icing can occur even with temperatures as high as 100°F (38°C) and humidity as low as 50 percent. This temperature drop can be as much as 60° to 70°F.

Question 4

Define the terms anti-icing equipment and deicing equipment and state several examples of each.

Answer 4

Anti-icing equipment—prevents ice from forming on certain protected surfaces. Examples are heated pitot tubes and static ports, carburetor heat, heated fuel vents, propeller blades with electro-thermal boots, and heated windshields. It is normally actuated prior to flight into suspected icing conditions. Reference your AFM/POH.

Deicing equipment—removes ice that has already formed on protected surfaces. It is generally limited to pneumatic boots on the wing and tail leading edges.

Question 5

Describe how an aircraft deicing system works.

Answer 5

Upon pilot actuation, boots attached to the wing leading edges inflate with air from a pneumatic pump(s) to break off accumulated ice. After a few seconds of inflation, they are deflated back to their normal position with vacuum assistance. The pilot monitors the buildup of ice and cycles the boots as directed in the AFM/POH.

Question 6

If an airplane has anti-icing and/or deicing equipment installed, can it be flown into icing conditions?

Answer 6

Even though it may appear elaborate and complete, the presence of anti- icing and deicing equipment does not necessarily mean that an airplane is approved for flight in icing conditions. The AFM/POH, placards, and even the manufacturer should be consulted for specific determination of approvals and limitations.

Question 7

What is detonation?

Answer 7

Detonation is an uncontrolled, explosive ignition of the fuel/air mixture within the cylinder’s combustion chamber.

Question 8

What are some of the most common operational causes of detonation?

Answer 8

a. Using a lower fuel grade than that specified by the aircraft manufacturer.
b. Operating with extremely high manifold pressures in conjunction with low RPM.
c. Operating the engine at high power settings with an excessively lean mixture.
d. Extended ground operations or steep climbs where cylinder cooling is reduced.

Question 9

What action should be taken if detonation is suspected?

Answer 9

a. Ensure that the proper grade of fuel is used.
b. Keep the cowl flaps (if available) in the full-open position while on the ground to provide the maximum airflow through the cowling.
c. Use an enriched fuel mixture, as well as a shallow climb angle, to increase cylinder cooling during takeoff and initial climb.
d. Avoid extended, high power, steep climbs.
e. Develop the habit of monitoring the engine instruments to verify proper operation according to procedures established by the manufacturer.

Question 10

What is preignition?

Answer 10

Preignition occurs when the fuel/air mixture ignites prior to the engine’s normal ignition event resulting in reduced engine power and high operating temperatures.

Question 11

What action should be taken if preignition is suspected?

Answer 11

a. Reduce power.
b. Reduce the climb rate for better cooling.
c. Enrich the fuel/air mixture.
d. Open cowl flaps if available.

Question 12

During the before-takeoff runup, you switch the magnetos from the “BOTH” position to the “RIGHT” position and notice there is no RPM drop. What condition does this indicate?

Answer 12

The left P-lead is not grounding, or the engine has been running only on the right magneto because the left magneto has totally failed.

Question 13

Interpret the following Load Meter indications.

a. Load Meter indicates a high Amp Load (to the right)

b. Load Meter indicates a low amp load (Left)

Answer 13

High Load:
- Possible short or faulty equipment
- Battery low, failed
- Possible voltage regulator problem

Low load:
- no/few equipment turned on
- Alt Circuit breaker popped
- Alternator Failure

Question 14

How do you know if you have an electrical system problem

Answer 14

Load meter will show unusually high load (to the right). If this condition is more than 20 amps over the known load for the conditions, the following may be true:
- Possible short or faulty equipment
- Battery low, failed
- Possible voltage regulator problem

Question 15

What action should be taken if the load meter indicates a high load while in flight (more than 15-20 amps above expected)?

Answer 15

If the battery is charging this may be normal for a short period of time. if condition does not improve after about 5 minutes, do the following:
- turn Battery Switch off
- Reduce load by turning off non essential equipment

If no change
- Cycle Alt Switch (Reset Voltage regulator)

If no Change:
- Alt Switch OFF
- Batt Switch ON/As Required

If you have altitude and time:
- turn off all electrical devices
- selectively turn on systems watching load to see if you can isolate the offending system
- if condition does not change or improve, terminate flight and land as soon as possible for further investigation

Question 16

During a cross-country flight you notice that the oil pressure is low, but the oil temperature is normal. What is the problem and what action should be taken?

Answer 16

A low oil pressure in flight could be the result of any one of several problems, the most common being that of insufficient oil. If the oil temperature continues to remain normal, a clogged oil pressure relief
valve or an oil pressure gauge malfunction could be the culprit. In any case, a landing at the nearest airport is advisable to check for the cause of trouble.

Question 17

What procedures should be followed concerning a partial loss of power in flight?

Answer 17

If a partial loss of power occurs, the first priority is to establish and maintain a suitable airspeed (best glide airspeed if necessary). Then, select an emergency landing area and remain within gliding distance.

• Check fuel pressure - turn electric fuel pump on
• Check the mixture control.
• Turn on carb heat
• Check the amount of fuel in each tank and switch fuel tanks if necessary.
• Check that the primer control is all the way in and locked.
• Check the operation of the magnetos in all three positions; both, left or right.

Question 18

What procedures should be followed if an engine fire

develops in flight?

Answer 18

1. Fuel pump Off
2. Set the mixture control to “Idle cutoff.”
3. Set the fuel selector valve to “Off.”
4. Turn the master switch to “Off.”
5. Set the cabin heat and air vents to “Off”; leave the overhead vents “On.”
6. Establish an airspeed of 100 KIAS and increase the descent, if necessary, to find an airspeed that will provide for an incombustible mixture.
7. Execute a forced landing procedures checklist.

Question 19

What procedures should be followed if an engine fire develops on the ground during starting?

Answer 19

Continue to attempt an engine start as a start will cause flames and excess fuel to be sucked back through the carburetor.

a. If the engine starts:
• Increase the power to a higher RPM for a few moments; and
• Shut down the engine and inspect it.

b. If the engine does not start:
• Set the throttle to the “Full” position.
• Set the mixture control to “Idle cutoff.”
• Continue to try an engine start in an attempt to put out the fire by vacuum.

c. If the fire continues:
• Turn the ignition switch to “Off.”• Turn the master switch to “Off.”
• Set the fuel selector to “Off.”

In all cases, evacuate the aircraft and obtain a fire extinguisher and/or assistance.

Question 20

what does a Zero reading on the load meter indicate?

Answer 20

• Alt switch is off
• Alt Circuit breaker is out
• Failed alternator

Question 21

What is the ‘Normal’ operating range for the load meter?

Answer 21

Depends on equipment, but typically around 20-30 amps