Aircraft Instrument Systems

Question 1

What are the three fundamental pressure-sensing mechanisms used in aircraft instrument systems?

Answer 1

1. The Bourdon tube
2. The diaphragm or bellows
3. The solid-state sensing device

Question 2

What basic mechanism is used to measure oil, fuel, and oxygen pressures?

Answer 2

The Bourdon tube

Question 3

What mechanical means is used to measure pressure in an airspeed indicator?

Answer 3

A diaphragm

Question 4

A failure of an airspeed indicator needle to move is likely caused by what problem?

Answer 4

A blockage in the pitot head will prevent the creation of a differential pressure

Question 5

Who is authorized to perform the altimeter tests to determine the accuracy of the altimeter?

Answer 5

The manufacturer of the aircraft on which the tests are conducted, or a certified repair station properly equipped to perform the test

Question 6

Where are the requirements for the altimeter system tests found?

Answer 6

14 CFR part 43, Appendix E

Question 7

How often should an altimeter be checked if it’s installed in an aircraft used in IFR flight?

Answer 7

Every 24 calendar months

Question 8

How much difference is allowed between the altitude indication on the automatic pressure altitude reporting equipment and that on the altimeter?

Answer 8

125 feet

Question 9

To what altitude must altimeters be tested?

Answer 9

To the highest altitude the aircraft will be flown on the IFR flight

Question 10

What record must be made of a test of an altimeter?

Answer 10

The aircraft permanent maintenance record must show:
1. The date
2. Maximum altitude the altimeter was tested
3. The name of the person approving the aircraft for return to service

Question 11

To what avionic equipment is the output from an encoding altimeter connected?

Answer 11

The ATC transponder

Question 12

What is the allowable difference between the surveyed elevation of the airport and the indication on the altimeter when it is set to the local altimeter setting?

Answer 12

75 feet

Question 13

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

Answer 13

1. Airspeed indicator
2. Vertical speed indicator
3. Altimeter

Question 14

What are the differences between absolute, gauge, and differential pressure instrument systems?

Answer 14

• Absolute pressure instrument: measures actual pressure.
• Gauge pressure instruments: measure the difference between exiting barometric pressure and pressure inside a sealed container
• Differential pressure instruments: display the difference between two pressures

Question 15

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

Answer 15

Current atmospheric pressure

Question 16

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

Answer 16

The sensitive altimeter

Question 17

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

Answer 17

1. Scale errors
2. Hysteresis
3. Friction
4. Installation

Question 18

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

Answer 18

1. Altimeter
2. Vertical speed indicator
3. Airspeed and Mach meter in high-performance jets

Question 19

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

Answer 19

The holes are aerodynamically critical

Question 20

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

Answer 20

The static system leak test specified by FAR 91.411