Druck Pressure Sensor Applications

Aerospace Applications

Ground Test - Ironbird

Druck Type: PDCR 4000 Series, PMP 4000 Series, PTX 500/600 Series, PTX/PMP 1400

As the name suggests, this is a full scale replica of the airframe that is used for static ground testing.

Its purpose is to allow for sub-system integration and operational check-out. for example, the hydraulic system, primary flight controls, landing gear, etc., are assembled together and checked to see if they work as part of the final airframe set-up.

Pressure transducers are fitted across the Ironbird to monitor pressures like hydraulic system pressure. 

Engine Test

Druck Type: PDCR 4000, PMP 4000 Series, PDCR 2200 Series, PDCR/PMP 4100 Series

The major engine manufacturers use multi-channel pressure systems for pressure measurement within the engine test cell. The two main manufacturers are PSI and Scanivalve.

In addition, more traditional Ø1” x 3” transducers are used for specialised discrete measurements.

Flight Test

Druck Type: PMP 317 (new), PDCR 330 Series, PTX/PMP 3000 Series (new)

Airframe flight testing involves many hours of flight, performing many different tests. Pressure transducers are fitted to the airframe to provide additional performance data to the flight test engineers. Often they incur weight penalties so size and weight of the transducers is important, along with good performance over wide temperature ranges. Flight certification is generally not required.

Production Program Fit

“Production Program Fit” refers to transducers that are fitted to the production standard airplane. Transducer requirements vary for each application and therefore, the transducer is often custom-designed to meet the specification requirements.

The PTX/PMP 3000 Series is a new range of voltage output aerospace transducers certified for flight use. It is intended that this series will address many applications found on an airplane as described below.  
 
Engine Mounted Transducers

Druck Type: PDCR 330 Series, PTX/PMP 3000 Series (new)

Engine mounted transducers are fitted either direct or within the architecture of the accessory controls. Engine controls, commonly known as Digital Engine Control Units (DECU’s) or Full Authority Digital Engine Control (FADEC’s) receive measurements of pressure from various stages of the gas turbine. For example, P0 is the pressure measured at the inlet to the compressor and P3 is outlet pressure. Measurement is made with either the transducer mounted direct to the engine or within the accessory control box.

Oil pressure is measured by direct mounting to the engine and includes a differential measurement for either filter or bearing condition monitoring.

Airframe Transducers

Airframe applications are numerous and break down into the following sub-sections:-

Bleed Air Systems

Bleed air is taken from the aircraft engine and is used for numerous applications such as anti-icing and environmental control. Pressure transducers are required to ensure and monitor bleed air supply for these auxiliary systems. Bleed air can be very hot and therefore good performance over wide temperature is important. The location of installation is often exposed and susceptible to high levels of EMC and lightning strike.

Anti-Icing

Anti-icing systems are fitted to an airframe to prevent ice build up on critical flight surfaces such as leading edges and powerplant fan blades. One method of anti-icing is to use engine bleed air which is naturally hot and therefore prevents ice formation.

Auxiliary Power Units

Auxiliary Power Units or APU’s are found on most civil and military airframes. They are required to provide power to essential aircraft systems in the event of engine failure. In addition, it is sometimes used to start the main engine. The APU offers pressure transducer applications for oil pressure, compressor inlet and often a ratio between outlet and inlet.

Anti-Skid

Anti-skid systems are the aerospace equivalent of automotive anti-lock brake systems. Pressure transducers measure system hydraulic pressure and close the control loop to ensure no-skid condition for the brake system. Dual channel systems (or transducers) are often used for redundancy purpose for this critical pressure measurement application.

Braking Systems

Brake systems rely on the supply of main system hydraulic pressure in order to actuate the brakes to each wheel.

Cabin Pressurisation Systems

Cabin pressure systems control the environment inside the airframe. The main purpose is to ensure the safety and comfort of passengers and crew by ensuring that there is a pressurised cabin when referenced to the external atmosphere. Although the transducer is mounted in a relatively benign environment, high measurement performance is required.

De-Icing Systems

De-icing systems are different to anti-icing systems in that the ice has already formed. It is the responsibility of the de-icing system to remove it. There are a number of ways of achieving this, including electrical heaters, inflatable rubber structures, etc. The inflatable rubber is inflated using bleed air and on inflation, breaks away the build up of ice. Pressure transducers are used to monitor the inflation air pressure.

Environmental Control Systems

Environmental Control Systems, or ECS, control the environment within the airframe. The ECS has many functions, example, air conditioning, cabin pressurisation, etc. In some military applications the ECS may be responsible for pilot air delivery to his mask and prevention of external air entering the cockpit. This is achieved by maintaining a positive differential pressure between inside and outside the cockpit.

Fuel Systems

Whenever there is a fluid on an airplane, there is a need to measure pressure. Fuel system management and delivery is no exception. Fuel management not only involves measurement of available fuel in the tank, but also fuel is moved around the airframe in flight to assist with trim. Fuel feed to the engine is also an important measurement requiring pressure measurement.

Hydraulic Systems

The hydraulic system pressure on an airframe is crucial for the operation of the primary flight controls. The hydraulic pressure is used by the landing gear, brakes, flaps, rudder, etc., and therefore, there is two or even three systems per airframe for redundancy. Pressure monitoring points can appear throughout the airframe.

Landing Gear

Raising and lowering of landing gear relies on the supply of hydraulic system pressure. Pressure transducers are required to monitor hydraulic system pressure.

Nacelles

Nacelles is the term used for the engine cover which also holds the core onto the airframe via the pylon. Nacelles bring fuel to the engine and bleed air off it for the auxiliary systems such as anti-ice. Numerous pressure measurement points can be included within the nacelle.

Oxygen Systems

Oxygen is carried onboard an airplane for use in emergency due to loss of cabin pressure. There is usually two systems, one for crew and one for passengers. Many systems still use oxygen bottles which can have a pressure transducer fitted to monitor bottle pressure. Although the environment is relatively benign, reliable performance and cleanliness for oxygen service is required.
For all the above applications the Druck product will be based on the new PTX/PMP 3000 Series.

Air Data Measurements

Druck Type: RPT 200, RPT 200S

Air data instruments require high accuracy and stable measurement of pitot and static pressure. Druck Resonant Silicon Pressure Transducers (RPT) are ideally suited to these applications in either frequency/temperature or digital output. Applications include the measurement of airspeed, altitude, Rate of Climb (ROC) and interfacing direct to the Air Data Computer (ADC).

Refer to Druck in Aerospace for further application/market information.