Sensors
conditioning system. This means that
engine oil cannot contaminate the cabin
air. Each engine has two starter generators,
each 250kVA, that are used to start up the
engines and generate electricity. The air
conditioning system works electrically too.
The 787 has a so-called inerting system as
standard. This extracts nitrogen from the
air using a special filter system and directs
it into the tanks. This reduces the oxygen
percentage to such an extent that a fire
cannot be triggered, even in the event of
flying sparks.
Jürg Dobler, member of the executive
management for Keller AG für
Druckmesstechnik says, “There are
currently around 40,000 pressure sensors
from us in the air – 30,000 or so of which
are just for regulating cabin pressure. The
precise regulation of the cabin pressure is a
clear added bonus for passengers comfort,
particularly during take-off and landing.
“At present, practically the entire Airbus
fleet, the Brazilian Embraer, the
“Dreamliner” from Boeing and various
business jets are flying with Keller
pressure measurement technology.”
“Keller’s pressure measurement
technology has proven its reliability over
hundreds of thousands flying hours. For
example, error-free operating times of
between 200,000 and 400,000 hours are
required for cabin pressure sensors. In
most cases, field data is hard to come by,”
says Dr Günther Kaden, aircraft sensors
consultant at Keller AG für
Druckmesstechnik. “However, some time
ago, one of KELLER’s major clients
systems to ensure the right cabin
temperature is maintained. These packs
have an output of around 450kW. When
the systems are running at full capacity,
the cabin air is completely replaced every
three minutes. Unlike most 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been replaced by local electro-hydraulic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
optimizing the load on the aircraft
structure. The system automatically
controls re- and defueling.
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.
The so-called “Dreamliner” is a twinengined
long-haul aircraft with space for
up to 300 passengers. Despite its
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
AEROSPACETESTINGINTERNATIONAL.COM // SHOWCASE 117
2 // There are many
different applications for
pressure transmitters in
aviation (Photo: Keller AG)
/AEROSPACETESTINGINTERNATIONAL.COM