Pressure Instruments

Question 1

What are the three major categories of flight instruments?

Answer 1

Pressure
Gyroscopic
Magnetic

Question 2

What are the three (major) pressure instruments in an aircraft?

Answer 2

ASI
Altimeter
VSI

Question 3

What measures static pressure on an aircraft?

Answer 3

Static vent

Question 4

Static pressure is exerted…

Answer 4

Equally in all directions

Question 5

What pressure is exerted equally in all directions?

Answer 5

Static pressure

Question 6

What two factors influence the strength of dynamic pressure?

Answer 6

Speed of body relative to air
Density of air

Question 7

Dynamic pressure equation

Answer 7

1/2 Rho V-squared

Question 8

1/2 Rho V-squared = ?

Answer 8

Dynamic pressure

Question 9

Dynamic pressure varies directly with what?

Answer 9

V-squared

Question 10

What is ram pressure?

Answer 10

Total pressure

Question 11

How does an ASI scale indicate speed (simply)?

Answer 11

Instead of indicating pressure, it is calibrated to read in knots

Question 12

An ASI is essentially a recalibrated…?

Answer 12

Altimeter

Question 13

What two instruments rely only on static pressure?

Answer 13

Altimeter and VSI

Question 14

What instruments relies on both static and dynamic pressure?

Answer 14

ASI

Question 15

If using an alternate static source, what can be said of the pressure readings?

Answer 15

Cabin pressure is slightly less than atmospheric pressure

Question 16

What component sits within an ASI’s system?

Answer 16

Diaphragm

Question 17

The caution range on an ASI is given what colour?

Answer 17

Yellow

Question 18

What kind of speed is most related to dynamic pressure?

Answer 18

IAS

Question 19

What speed do aerodynamic qualities of an aircraft depend on?

Answer 19

IAS

Question 20

What speed do navigational purposes depend on?

Answer 20

TAS

Question 21

In a lift/drag equation, what kind of speed is ‘V’ in V-squared?

Answer 21

TAS

Question 22

If TAS is V in the lift/drag equation, how is IAS involved in the equation also?

Answer 22

In rho as a function of dynamic pressure

Question 23

Why must TAS increase in a climb at constant IAS?

Answer 23

Constant IAS means 1/2 rho v-squared must remain constant
Rho decreases in a climb so V (TAS) must increase

Question 24

At 5000ft, TAS exceeds IAS by approximately what percentage?

Answer 24

8%

Question 25

If a pitot/static vent becomes blocked, what can be said of the pressure at the time?

Answer 25

It will remain constant

Question 26

A block static vent has what effect on an ASI in a climb?

Answer 26

ASI will under-read

Question 27

A block static vent has what effect on an ASI in a descent?

Answer 27

ASI will over-read

Question 28

Pneumonic for remembering block static vent/pitot in a descent?

Answer 28

PUDSOD

Question 29

Describe the pressure relationships in an ASI when a static vent is blocked in a climb?

Answer 29

Trapped pressure is greater than outside pressure Total - Static Pressure = lower dynamic pressure than actual

Question 30

Describe the pressure relationships in an ASI when a static vent is blocked in a descent?

Answer 30

Trapped pressure is lesser than outside pressure Total - Static Pressure = greater dynamic pressure than actual

Question 31

In an ASI, a higher dynamic pressure equates to what?

Answer 31

Higher IAS

Question 32

A blocked pitot on take-off will have what effect on the ASI?

Answer 32

Only static pressure will be fed to ASI ASI will read 0