Jeppesen Oral- Chapter 11 (Aircraft Instrument Systems )

Question 1

What instruments in an aircraft are connected to the static system?

Answer 1

instruments in an aircraft are connected to the static system?
The airspeed indicator, the vertical speed indicator, and the altimeter

Question 2

What types of repairs or alterations can a certificated A&P mechanic make to aircraft instruments

Answer 2

None. All repairs and alterations must be made by the instrument manufacturer or by an FAA-approved repair station certificated for the particular instrumen

Question 3

WHat is the significance of a red radial line on the dial of an aircraft instrument?

Answer 3

A red radial line marks a never-exceed conditon.

Question 4

What is the significance of a yellow arc on the dial of an aircraft instrument?

Answer 4

A yellow arc marks a caution range of operation.

Question 5

What is the significance of a green arc on the dial of an airspeed indicator?

Answer 5

A green arc indicates the normal range of operation.

Question 6

What is the significance of a white arc on the dial of an airspeed indicator?

Answer 6

A white arc on an airspeed indicator indicates the airspeed at which the flaps may be lowered.

Question 7

What is used to warn a mechanic that the glass on an aircraft instrument that contains the range marks has slipped?

Answer 7

A white slippage mark that extends across the lower part of the instrument conver glass and the instrument case bezel shows whether or not the glass has slipped. A slipped glass would put the range marks over the incorrect numbers.

Question 8

Where can a mechanic find the range markings that are required on the instruments in a particular aircraft?

Answer 8

In the Type Certificate Data Sheets for the aircraft

Question 9

What check must be made if a mechanic replaces any instrument that is connected to the instrument static system?

Answer 9

The static system must be checked for leaks.

Question 10

Why are many of the electrical systems mounted in steel cases?

Answer 10

A steel case concentrates the flux produced by magnets in the instrument and keeps it from affecting other nearby instruments.

Question 11

Why must an aircraft instrument panel be electrically bonded to the primary aircraft structure?

Answer 11

The bonding straps carry the return current from the instruments into the aircraft structure.

Question 12

What error is corrected when an aircraft compass is swung?

Answer 12

deviation error

Question 13

What fluid is used in an aircraft magnetic compass?

Answer 13

A special water-clear fluid that is similar to kerosene.

Question 14

What is the maximum amount of deviation error that is allowed when a magnetic compass is installed in an aircraft?

Answer 14

10 degrees

Question 15

What is the maximum amount of leakage that is allowed when checking the static system of an aircraft that is operated under Instrument Flight Rules?

Answer 15

For an unpressurized aircraft, the system is checked with a 1,000-foot indication on the altimeter. It must not leak more than 100 feet in one minute. For a pressurized aircraft, the system is checked at the maximum certificated pressure differential of the cabin. It must not leak, in one minute, more than 2% of the equivalent altitude of the maximum differential pressure or 100 feet,whichever is greater.

Question 16

Why must the length of the thermocouple leads not be altered when installing a cylinder head temperature indicator?

Answer 16

An instrument operated by a thermocouple is a current-measuring device. The resistance of the thermocouple and its leads must be kept at the value specified for the indicator.

Question 17

What should a manifold pressure gauge read when the engine is not operating?

Answer 17

It should read the existing barometric pressure.

Question 18

What is the difference between a two-minute and a four-minute turn and slip indicator?

Answer 18

A two-minute turn indicator gives a one-needle-width deflection for a standard rate of turn (three degrees per second). A four-minute turn indicator gives a one-needle-width deflection for a half-standard rate of turn (1-1/2 degrees per second). A four-minute turn indicator has doghouse shaped marks located two needle widths away from the center mark. When the needle is lined up with a doghouse, the aircraft is making a standard rate turn.

Question 19

What is the difference between a turn and slip indicator and a turn coordinator?

Answer 19

A turn and slip indicator is sensitive about only the yaw (vertical) axis of the aircraft. A turn coordinator uses a canted gyro which makes it sensitive about both the roll and yaw axes.

Question 20

What is used as the sensor in the fuel tank for an electric-type fuel quantity indicating system?

Answer 20

Tubular capacitors which extend across the fuel tank from top to bottom.

Question 21

Why is a dual tachometer used on a single-engine helicopter?

Answer 21

One needle indicates the speed of the engine, and the other indicates the speed of the main rotor. When the needles are married, the clutch is not slipping and the rotor is solidly engaged to the engine.

Question 22

In what units is the tachometer used on a turbine engine calibrated.

Answer 22

In percentage of the takeoff RPM

Question 23

What kind of system is used to measure the exhaust gas temperature of a turbine engine?

Answer 23

An averaging system made up of a series of thermocouples arranged around the inside duct of the engine.

Question 24

What would likely cause the needle of an electrical oil temperature gauge to peg on the high side of the instrument dial?

Answer 24

There is probably an open in the bulb circuit that is causing the instrument to see an infinite resistance. The higher the resistance of the bulb circuit, the further the needle moves across the dial.

Question 25

What is used as a flowmeter for most of the small horizontally opposed fuel-injected aircraft engines.

Answer 25

A pressure gauge that measures the pressure drop across the injector nozzles.

Question 26

What two sources of power are used to operate the gyro instruments in an aircraft?

Answer 26

They may be air operated, either by suction or pressure, or they may be electrically operated.

Question 27

A static check may be performed on a manifold pressure gauge by using what piece of information?

Answer 27

Current atmospheric pressure

Question 28

What aircraft instrument can be used to check a manifold pressure gauge for proper indication?

Answer 28

The sensitive altimeter

Question 29

Name several of the indication errors that may be found in altimeters.

Answer 29

Scale errors, hysteresis, friction, installation.

Question 30

What is the signal source in an electrical resistance-type temperature indicating system?

Answer 30

A temperature bulb or sensing element

Question 31

What type of temperature sensing system is normally used to measure a turbine engine exhaust gas temperature?

Answer 31

A thermocouple-type system

Question 32

What operating parameter is indicated by a tachometer?

Answer 32

Engine RPM (i.e. crankshaft or turbine rotor speed).

Question 33

What is the name of the effect that causes a gyro to respond to an applied force at a point 90 degrees further in the direction of rotation?

Answer 33

Gyroscopic precession

Question 34

What are the three sources of power used to drive a gyroscopic turn indicator?

Answer 34

Air from a vacuum or pressure source, or an electric motor.

Question 35

What are two items that should be considered during inspection of a magnetic compass?

Answer 35

1. The fluid must be clear.
2. The housing must be full with no bubbles.
3. The card must be legible and the lubber line intact.
4. The compass should be properly calibrated.

Question 36

In what way do magnetic fields generated by electrical equpiment and steel parts in an airplane affect a magnetic compass?

Answer 36

Stray magnetic fields deflect the compass from correct alignment with the earth’s magnetic field.

Question 37

Describe the basic operating concept of a synchro-type remote indicating system.

Answer 37

remote transmitter electrically signals a receiver inside the instrument.

Question 38

What aircraft instruments are connected to the pitot-static system?

Answer 38

The altimeter, vertical speed indicator, airspeed indicator, airspeed and mach meter in high-performance jets.

Question 39

Why should you avoid cleaning obstructions from the sensing holes in a pitot-static system with a tool?

Answer 39

The holes are aerodynamically critical.

Question 40

After components in a pitot-static system have been replaced, what tests or inspections are required?

Answer 40

THe static system leak test specified by FAR 91.411.

Question 41

What quantity is accurately measured by a capacitance-type fuel quantity indicating system?

Answer 41

mass of the fuel

Question 42

Who is authorized to apply the range markings to an instrument dial face?

Answer 42

The manufacturer or a certificated instrument repair station.

Question 43

What is the purpose of a slippage mark on an instrument glass?

Answer 43

To indicate if the glass has moved, which could cause incorrect range markings on an instrument that has the range markings painted on the glass.

Question 44

What references should be consulted to determine the proper range markings for aircraft instruments?

Answer 44

The aircraft maintenance manual, aircraft flight manual, Type Certificate Data Sheets, or Aircraft Specifications.

Question 45

What is the meaning of a yellow arc on an aircraft instrument?

Answer 45

A caution or limited flight operations range.

Question 46

What is the reason for “swinging” a compass and how is it accomplished?

Answer 46

To compensate for deviations, caused by magnetic fields in the aircraft, by adjusting the compensating magnets.