Testing time for business jet.
Development and qualification testing of three flap
system actuators for the eagerly awaited new Falcon
7X business jet is being performed on a test rig
designed and built by Comar Engineering in
Wolverhampton and incorporating an innovative
non-contact torque transducer.
The whole Falcon 7X project is packed with innovation, from the
virtual design techniques used in the early stages that compressed
the development time to a level totally unexpected in the aviation
industry, through to the choice of electric actuators rather than
hydraulic for driving the flight control surfaces. It will be the world's
first fly-by-wire business jet, offering the pilots benefits previously
only enjoyed in fighter jets such as precise flight path control and
automatic trim adjustments during configuration changes. Carrying
up to 19 passengers it is a long range aircraft that can operate
from modest airfield; as such it could help to change the face of
business travel in the coming decades.
Comar built a test rig incorporating 22Nm and 200 Nm TorqSense
transducers from Sensor Technology in Bicester for the development
and qualification testing of three flap system actuators, including
Production Acceptance Tests, Performance, Endurance, Mechanical
Fatigue and Mechanical Strength tests.
One of the key reasons for selecting TorqSense transducers for the
test rig was that they do not need to be physically connected to the
test piece via a complicated set of slip rings which would be time
consuming to assemble and dismantle between each test sequence.
In effect a TorqSense transducer is a frequency dependent strain
gauge operating at ultrasound frequencies and consists of a
piezoelectric comb mounted on the test shaft to monitors variations
in its resonance frequency as the torsional load varies. An RF
(radio frequency) link is used for wireless transmission of signals
to an adjacent pick up so that rotation is unhindered.
Each flap system consists of a power drive unit (PDU) and four
actuators all of which are linked together via transmission shafts
and gearboxes, these units are operated via the slat/flap airbrake
control unit. The flap actuators are ballscrews and are configured
so that the screw translates through a jackhead into a linear motion.
When the flap system is commanded the PDU applies a torque
to the actuator input via the transmission shafting, the rotational
input is converted into a lateral movement of the screw and thus
the flap surface. The actuator can be commanded to extend and
retract to 4 different positions: zero, 7 degrees, 20 degrees and
40 degrees. As the actuator extends a compressive load is
applied as a result of the aerodynamic load on the flap surface
increasing, this translates into varying torque levels.
Comar's test rig is designed to apply simulated conditions of
load profiles via the computer operated system. Each actuator
is tested with a servo hydraulic motor input drive in closed loop
control of position against torque which is monitored using the
smaller 22Nm TorqSense; the load to the ballscrew lateral
motion is applied via a servo cylinder again in closed loop
control of position against load.
Proof loading is applied manually to the input drive using a
gearbox and the larger 200Nm torque transducer in open loop.
Typical tests performed include: no load input torque, compressive
loads, tensile loads, running in, backlash, efficiency, performance
and endurance (one endurance life being 20,000 operating cycles).
Like all aircraft components, the Falcon 7X flap systems were
subjected to rigorous and repeating test regimes during their
development, and similar tests will be rerun throughout their
operating life. The use of a non-contact transducer therefore
saves considerable time over the lifecycle of the Falcon 7X.
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For more information, please contact :-
Sensor Technology Ltd.
Tel: +44(0)1295 730746 Fax: +44(0)1295 738966
Email: info@sensors.co.uk
Website: www.sensors.co.uk
August 2005
