Understanding Mercury Barometers

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What happens to the mercury column in a mercury barometer when atmospheric pressure increases?

It is forced higher up the tube (correct)

It remains at the same level

It drops lower in the tube

It is pushed out of the tube

What is the primary function of a pitot probe in an aircraft?

To measure airspeed (correct)

To measure static pressure

To detect moisture in the airstream

To negate the effect of air temperature

Why would a mercury barometer not be practical to mount in an aircraft?

Because it is too heavy

Because it is not suitable for changes in pressure at high altitudes (correct)

Because it is too large

Because it is not sensitive enough

Why is a small calibrated drain hole added to the pitot probe?

To allow moisture to escape Signup and view all the answers

What would be the result of using water instead of mercury in a barometer?

The tube would need to be much longer Signup and view all the answers

What is the maximum operating range of an aneroid capsule?

0 psia to 17 psia Signup and view all the answers

What is the purpose of the electrical heater element in the pitot probe?

To prevent moisture from freezing Signup and view all the answers

What type of elements are used in an aircraft to measure atmospheric pressure?

Elastic pressure-sensing elements Signup and view all the answers

What is the term used to describe the element that measures static pressure in an aircraft?

Static port Signup and view all the answers

In some light aircraft, what is the simple form of a static port?

A hole drilled in the fuselage skin Signup and view all the answers

What is the purpose of an aneroid capsule?

To measure very small changes in pressure Signup and view all the answers

What is the purpose of the static port in an aircraft?

To measure static pressure Signup and view all the answers

What is the purpose of the third pointer or trace pointer in an altimeter?

To eliminate ambiguity created by the second pointer Signup and view all the answers

What happens to the striped disc or cross hatch flag between 10 000 feet and 16 000 feet?

It gradually retracts from view Signup and view all the answers

What causes the aneroid capsules to expand and move the pointers in an altimeter?

A decrease in air pressure outside the aircraft Signup and view all the answers

What is the function of the vibrator in some aircraft altimeters?

To prevent the sticking of the mechanism Signup and view all the answers

How are the aneroid capsules sealed?

At the factory Signup and view all the answers

What connects the case of the altimeter to the aircraft?

Hose and tubing Signup and view all the answers

What occurs when the spin axis of the rotor becomes aligned with the axis of the outer gimbal?

Gimbal Lock Signup and view all the answers

What is a major issue with traditional Vertical Speed Indicators in helicopters?

They display out-of-date information during rapid descent rates Signup and view all the answers

Why are mechanical stops used in a gimbal system?

To prevent gimbal lock Signup and view all the answers

What happens when the inner gimbal reaches the mechanical stops?

The outer gimbal rotates 180 degrees Signup and view all the answers

What is the primary function of the accelerometer unit in an Instantaneous Vertical Speed Indicator?

To provide a more rapid differential pressure effect Signup and view all the answers

What is the cause of unavoidable precession during aircraft maneuvering?

Friction of gimbal bearings Signup and view all the answers

How does the piston in the accelerometer respond to a change in vertical speed?

It moves under the influence of the vertical acceleration force Signup and view all the answers

What is the consequence of deflective forces being too strong or applied rapidly to a gyro rotor?

Toppling over Signup and view all the answers

What is the purpose of the spring in the accelerometer's design?

To hold the piston in balance Signup and view all the answers

What happens to the pressure inside the capsule during the initiation of a descent?

It increases immediately Signup and view all the answers

What is the potential consequence of a gyro rotor toppling over?

It may jump from the bench and destroy itself Signup and view all the answers

How long does the accelerometer response typically last?

A few seconds Signup and view all the answers