Elec reviewer 1st reviewer

Pressure Measuring Instruments

A number of instruments inform the pilot of the aircraft's condition and flight situations through the measurement of pressure.

Pressure-sensing instruments

can be found in the flight group and the engine group. They can be either direct reading or remote sensing. These are some of the most critical instruments on the aircraft and must accurately inform the pilot to maintain safe operations.

Pressure measurement

involves some sort of mechanism that can sense changes in pressure. A technique for calibration and displaying the information is then added to inform the pilot.

Bourdon tube, the diaphragm or bellows, and the solid-state sensing device.

The type of pressure needed to be measured often makes one sensing mechanism more suited for use in a particular instance. The three fundamental pressure-sensing mechanisms used in aircraft instrument systems are the

the safety of the airplane, the crew, and the passengers depends on the proper installation and correctoperation of the instruments.

the first particularly important reason why the principles of operation and the art of interpreting interpret the the readings re of instruments used in modern aircraft that should be thoroughly understood by the maintenance technician.

they provide many indications of impending powerplant or system failure.

Second reason why the technician must understand the operating principles of instruments is that

Pressure-type instruments

Mechanical instruments

Gyro Instruments

Electrical and electronic instruments

Classification of instruments according to the means by which they give their indication

Bourdon tube

It works when pressure enters it, it tends to straighten out, and as it does so, it moves the linkage connected to the sector gear. The movement of the sector gear causes the spur gear to rotate, and this in turn moves the indicating needle along the scale to give reading of the pressure

Aircraft Instruments

These are devices/appliances installed in an aircraft, typically in the cockpit, that provides the pilot/s with essential aeronautical information in order for the pilot/s to safely and efficiently operate the aircraft.

Bourdon Tube

Instrument which measures pressures in
relatively high pressure fluid systems.

Power Plant Instruments

Flight and navigational Instruments

System Instruments

Instruments on the plane my be classified according to function in three principal categories

Bourdon Tube

Indications requiring this type of instruments are hydraulic pressure, engine oil pressure, oxygen pressure, and any other indication of comparatively high pressures.

Bourdon Tube

is constructed of metal and is oval or flattened in cross-sectional shape, with the tube itself formed into a crescent or part circle.

Bourdon Tube

Constructed of a metal such as spring-tempered brass, bronze, or beryllium copper.

Bourdon Tube

When pressure enters it, it tends to straighten out, and as it does so, it moves the linkage connected to the sector gear. The movement of the sector gear causes the spur gear to rotate, and this in turn moves the indicating needle along the scale to give a reading of the pressure

Atmospheric Pressure

Is due to the weight of the air in the atmosphere enveloping the earth and is taken as the pressure due to a column of air extending from sea level to the upper limits of the earth’s atmosphere

Absolute Pressure

This is a method of pressure measurement which has a perfect vacuum of zero

Gauge Pressure

Uses a datum, such as existing atmospheric pressure at zero. Below which, pressure is considered negative and above which is considered positive.

Diaphragms

Pressure gages designed to provide readings of comparatively low pressure are usually of the ______.

Diaphragms

Is a corrugated circular metal discs, or circular rubberd discs

The purpose of the corrugation is to permit larger deflections furthermore, their number and depth control response and sensitivity characteristics;

Diaphragms

consists of two discs of metal Corrugated concentrically and sealed together to form cavity or capsule.

Is designed with an opening through one of the disc to admit the pressure to be measured. The opposite side is provided with a bridge that bear against a rocking shaft lever through which the movement is transmitted to the indicating needle.

Bellows

It is used for low to intermediate pressures

Bellows

They are used in vacuum, absolute and differential pressure application.

It expands or contracts based on the pressure difference across the inside and outside

Elasticity

Corrosion Resistance

Temperature Stability

MATERIAL PROPERTIES that affect aircraft components

Elasticity

The material must return to its original shape after deformation.

Stiffer materials may affect the semsitivity.

It is under material properties

Corrosion Resistance

Exposure to different environments can lead to material degradation

It is under material properties

Temperature Stability

Variations in temperature can affect material properties and performance. It is under material properties

Pressure Sensitivity

The accuracy of measurements depends on the material's response to pressure.

It is under pressure range

Overpressure

Exceeding the designed pressure range can cause permanent deformation or failure.

It is under pressure range

Precision

Manufacturing defects or inconsistencies can affect performance and accuracy.

it is under manufacturing quality.

Surface Finish

Smooth surfaces are crucial for consistent and reliable operation.

It is under manufacturing quality.

Fatigue

Repeated pressure cycling can lead to fatigue and eventual failure. It is under mechanical stress

Installation

Improper installation or alignment can affect accuracy and longevity. It is under mechanical stress.

Vibration

Continuous vibration can cause wear and affect the accuracy of the instrument.

It is under environmental conditions.

Humidity

High humidity can lead to corrosion or changes in material properties.

It is under environmental conditions

Accuracy

Regular calibration is necessary to ensure that the instrument remains accurate overtime. It is under calibration.