What Are the Pressure Measuring Mechanisms and Instruments Used in Aircraft?

As aircraft rely on hydraulic systems, fuel components, and other such fluid apparatuses for their standard operations, it is important that there are methods and mechanisms in place for measuring pressure. This is due to the fact that aircraft constantly undergo changes in altitude, weather, and temperature as they conduct flight operations, all of which cause changes in pressure. Furthermore, pressure can also be utilized by many instruments in order to provide the pilot with flight-pertinent information for the means of conducting safe operations. In this blog, we will provide an overview of some of the main types of pressure measuring instruments and mechanisms in aircraft, allowing you to better understand their uses and importance.

As some of the most important flight instruments for conducting operations, pressure measuring instruments are implemented throughout the aircraft in both the flight group and engine group. Depending on their functionality and what they are measuring, such instruments may be direct reading or remote sensing. Despite these differences, all function on the basic principle of detecting changes in pressure and utilizing such data to relay information to a pilot. On a typical aircraft, the most common types of pressure measuring mechanisms that allow for instruments to function are diaphragms, Bourdon tubes, and solid-state sensing devices.

With a diaphragm pressure gauge, gas and liquid pressure can be measured through the force it enacts upon the component. As pressure is exerted on the disk of the diaphragm, the disk will begin to expand in response. By measuring the amount of expansion, the instrument can make a reading. Diaphragms can also be connected together in order to achieve more complex readings, and such assemblies are known as bellows. With bellows, differential pressure readings can be achieved through the measurement of two separate gases.

The Bourdon tube is another pressure mechanism that is popularly used for aircraft pressure measurement instruments due to their high reliability and simplicity. As a fixed coiled tube with a free end, fluids can enter into the tube and exert pressure against the enclosed free end. The higher the pressure of the fluid in question, the more it will cause the Bourdon tube to straighten out. As such, the straightening of the tube can be measured by an instrument, allowing for a reading to be obtained. Such mechanisms are often used in instruments such as fuel pressure gauges, those of which will be covered later.

Lastly, solid-state sensing devices are components which allow for pressure changes to be measured for the use of flight computers and other instruments. To measure pressure, the solid-state sensing device features an electrical output or resistance that will adjust as more or less pressure is exerted upon it. With crystal embedded wires or a pressure-sensitive chip, electricity can be created through fluid pressure, thus causing an electrical signal that can be used for relaying data.

With the various pressure measuring mechanisms, various flight-critical instruments may be provided with data that is paramount to safety. By using the engine oil pressure gauge, the well-being of the engine can be monitored by the pilot to ensure that values always remain in an acceptable operating range. Oil is crucial to the operation of any aircraft, as it allows for rapidly moving shafts, gears, and other components to be lubricated and cooled. If pressure were to drop due to various issues, high amounts of resulting friction could damage a system beyond repair or lead to an engine failure. As such, aircraft will utilize digital or mechanical oil pressure gauges for measurement and safety.

Similar to oil pressure, fuel pressure gauges monitor the pressure of liquids in order to ensure that safe values are maintained for optimal functionality. As fuel tanks require pressure for the transportation of fuel from the tank to a turbine engine or other powerplant, fuel pressure gauges are highly important for safety. Due to the danger of having fuel travelling near the aircraft cockpit, sensing mechanisms are used alongside transmitter devices in order to relay oil pressure readings to pilots.

With the pitot-static system, pressure measurements can be used to receive flight-pertinent information that highly benefits pilots during operations. With the altimeter, airspeed indicator, and vertical speed indicator, pressure from pitot and static lines can be measured with diaphragms and other mechanisms in order to determine the aircraft’s height, airspeed, and vertical rate of climbing and descent. As compared to some of the liquid pressure gauges, the pitot-static system is connected directly to cockpit instruments in order to provide readings.

Beyond oil pressure gauges, fuel pressure gauges, and the pitot-static system, many other pressure measuring mechanisms and instruments may be present on an aircraft for increasing safety and efficiency. At NSN Supplies, we can help you secure the pressure switches, cockpit display parts, chip sensors, speed indicators, and other aircraft parts and systems that you need to carry out your operations with ease. As a leader among parts distributors, we provide our customers with rapid lead-times and competitive pricing on our offered parts to save them time and money. Additionally, we enact rigorous quality assurance testing, inspection, and cross-referencing for all of our parts to guarantee their reliability. Let us be your strategic sourcing partner today with a personalized quote when you fill out and submit an Instant RFQ form as provided through our website.


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