Test & measurement Security for aviation and

space travel M

any people get an uneasy feeling when they board an aeroplane, as opposed to when using a car, even though the

latter presents a significantly higher likelihood of being involved in an accident. According to the Federal Association of German Aviation (BDL) and the Aviation Safety Network (ASN), a total of four billion passengers were transported by air in 2017, 79 of whom died in ten civil aviation accidents. In 2017, the risk of losing your life on a commercial flight had fallen to its lowest level since records began. According to the BDL, in 2017, 13 times more passengers were being transported by airlines than in 1970. Despite this growing number, the statistical probability of being killed in a plane crash averaged one in 264,000 in the 1970s and stood at around one in 92,750, 000 in 2017. This means that flights were 350 times safer in 2017 than they were in the 1970s. These records do not take account of accidents involving military aircraft or smaller aeroplanes with less than 14 passenger seats on board. This success is due to the improvement in aviation technology, airport infrastructure and air traffic control. Nowadays, aeroplanes are generally less susceptible to interference. This success can also be due down to the careful selection and strict screening of suppliers and their products.

KELLER PRESSURE TRANSMITTERS IN AVIATION KELLER has been supplying pressure sensors to all manner of aircraft fleet sectors since 1997. The main application areas are: cabin pressure control; hydraulic distributors and filters; valve control; fuel pumps; refueling systems; air conditioning systems; ventilation; and emergency oxygen supply for pilots. Ten different pressure transmitters are used

throughout the entire aircraft. Depending on the type of aircraft, either all application areas are handled by KELLER, or only certain parts of them.


The specific application description is subject to an obligation of secrecy. Three types of aircraft are, however, described below that show how different these can be and thus how broad the spectrum of demands on pressure measurement technology is.

AIRBUS A380 The four-engined wide- bodied A380 aircraft has two fulllength passenger decks and a capacity of up to 853 passengers, making it the largest civil series aircraft. It has an

operating range of 15,200 km and a cruising speed of approximately 900 km/h. Two compact air conditioning systems ensure the right temperature is maintained. These packs have an output of around 450 kW. When the systems are running at full capacity, the cabin air is completely replaced every three minutes. Unlike common commercial aircraft, the A380 has just two hydraulic circuits. The third hydraulic circuit has been replaced by local electro-hydraulic actuators. This saves weight as there are fewer cables and valves. The fuel tanks are part of the supporting structure and are located in the wings and the elevator unit. By means of controlled emptying of the tanks, the centre of gravity of the airplane can be automatically adjusted during the entire flight, thus optimising the load on the aircraft structure. The system automatically controls re- and defueling.

AIRBUS A400M The Airbus A400M is to replace or supplement the largely obsolete fleet of transport aircraft

in the air forces of seven European NATO states. The four-engined machine has turboprop engines and an accessible tail ramp, and can take off from short, unpaved runways. Although the A400M is already widely used, its technical development has not yet been concluded.

BOEING 787 The so-called “Dreamliner” is a twin-engined long-haul aircraft with space for up to 300 passengers. It is the first “twin-aisle” wide- bodied aircraft whose body is made primarily of carbon-fibre reinforced plastic (CFRP). In view of the reduced weight, the newly developed engines and improved aerodynamics should save 20 per cent of fuel and be significantly quieter. Yet, despite the lightweight design, the “Dreamliner” still meets the specified cabin noise limits. The special feature of the engines is that they do not release any bleed air into the air conditioning system. This means that engine oil cannot contaminate the cabin air. Each engine has two starter generators, each

October 2020 Instrumentation Monthly

The aeroplane is one of the safest modes of transport in the world. This can be attributed to the excellent training of the pilots and the sophisticated technology both on board and on the ground. This applies even more so to space travel. This is where KELLER AG für Druckmesstechnik joins the ranks of suppliers of high-security technology with its transmitters

Absolute and differential pressure transmitters regulate regenerative

processes in the oxygen supply on the International Space Station (ISS)

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