11.5 Pitot Static

Question 1

Mixture of gases =

Answer 1

78% nitrogen, 21% oxygen, 1% other gases

Question 2

Weight of atmosphere on earths surface is?

Answer 2

14.7 PSI

Question 3

All of the worlds weather is contained in the?

Answer 3

Troposphere

Question 4

Where does the tropopause begin?

Answer 4

Where temperature stablises at -56C

Question 5

ISA specifies SEA LEVEL

Answer 5

Question 6

The amount of pressure change pitot static instruments are calibrated to measure is?

Answer 6

10 PSI making them very sensitive instruments., That 10 psi is the difference between sea level and 40,000 feet

Question 7

At 10,000 feet atmospheric pressure is?

Answer 7

2/3 that of the pressure at sea level.

Question 8

At 18000 feet atmospheric pressure is?

Answer 8

1/2 that of the pressure at sea level

Question 9

The altimeter measures?

Answer 9

Atmospheric pressure, which surrounds the aircraft and displays this in pressure in units of feet above sea level.

Question 10

One capsule will expand or contract around?

Answer 10

.001mm for each millibar of pressure change.

Question 11

What is used for temperature compensation on altimeters?

Answer 11

Bi metallic strips
Brass = high coefficient
Invar = Low coefficient

Question 12

What happens to the bi mettalic strips when they are heated or cooled?

Answer 12

Heated = Brass expands more than invar
Cooled = Brass contracts more than invar

Question 13

The pressure sensing element of an altimeter is compensated for changes in ambient temperature by?

Answer 13

Bi-metal U shaped bracket.
Decrease in temp = limbs bend inwards, pushing pins onto capsule limiting expansion

Question 14

Elements of an altimeter

Answer 14

Question 15

Static vents interconnect via?

Answer 15

A common manifold to average and minimise dynamic pressure effects due to yawing or sideslip of the aircraft

Question 16

What altimeter is this?

Answer 16

Non sensitive, 1 capsule, 1 pointer. Used in small aircraft that don’t go above 10K feet, VFR

Question 17

What type of altimeter is this?

Answer 17

Sensitive altimeter, stack of capsules, 3 or 2 needs with a drum readout. IFR, 35K to 50K feet

Question 18

What is the purpose of the striped disc/ cross hatch flag?

Answer 18

Passive low altitude warning device. 10,000 to 16,000 feet

Question 19

Regulatory checks of altimeters are every?

Answer 19

24 Months.

Question 20

When do Static systems need to be tested?

Answer 20

As prescribed in regulatory & maintenance documentation.

Question 21

Describe Airspeed

Answer 21

Indication of an aircrafts speed through the surrounding air indicated airs[peed is measure, displayed in knotes.

Question 22

What is airspeed measuring?

Answer 22

Dynamic pressure (pitot) and Static Pressure with regard to airflow. Movement of the aircraft through the air causes the dynamic pressure to become greater than that in the static pressure.

Question 23

Elements of an airspeed indicator.

Answer 23

Question 24

How are pitot probes drained of moisture?

Answer 24

A small calibrated drain hole allows this moisture to escape without affecting the sensed pressure.

Question 25

What does the Red radial line indicate?

Answer 25

Maximum speed limited by structural consideratrions of the airframe.

Question 26

Where is the stall speed located?

Answer 26

Low speed end of the green or white ranges.

Question 27

What replaces the fixed red line on an Maximum allowable airspeed indicator?

Answer 27

Red and white striped barbers pole, used on aircraft that can achieve high cruise altitudes.

Question 28

What is the Critical Mach Number? Mcrit?

Answer 28

Mach number at which supersonic airflow first occurs at any point on the airframe.

Question 29

Describe as Machmeter

Answer 29

Instrument that accepts two variables, airspeed and altitude, using them to compute the required ratio.

Question 30

What is this?

Answer 30

Instantaneous vertical speed indicator

Question 31

During testing you are required to tape over pitot static connections, what must be done?

Answer 31

Highly contrasting tape colour, adequate length to form an easily visible tail

Question 32

To guard against cross connection the pitot static lines are usually?

Answer 32

Penis = Smaller diameter than static. Red = Pitot Green/Blue = Static

Question 33

Pitot tube blockages prevent accurate indications of airspeed but have?

Answer 33

No effect on the altimeter or vertical speed indicator.

Question 34

What are the limits for UN pressurised pitot static systems

Answer 34

Must not leak at a rate greater than 100 feet in one minute.

Question 35

Apply a pressure to the pitot system to cause the airspeed indicator to read 150 knots, what is the allowable leak rates?

Answer 35

Maximum permitted loss is 10 knots in one minute.

Question 36

Pressurised aircraft leak rates?

Answer 36

2% of original altitude or 100 feet in one minute.

Question 37

As a regulatory minimum an IFR! aircraft must have the pitot static system leak tested every?

Answer 37

1. 2 years 2. Opening or closing of pitot static lines 3. ATC transponder maintenance 4. When instrument accuracy is questioned.