WHEN Airbus purchased specialised cable-extension transducers to perform wing-fatigue tests on its new A380 aircraft, it chose Celesco, from IDM Instruments .
In the fatigue tests, hydraulic cylinders are used to flex the wings upwards and downwards in a vertical motion that simulates the movement of the wings during take-off and landing. For the tests, Celesco modified its PT1A unit for 2-inch, 20-inch and 40-inch strokes.
Celesco also had to meet Airbus’s stringent “interlinearity” specification. This refers to the difference between maximum and minimum sensitivity from a manufacturing lot of sensors, all with the same stroke range. Airbus required that the sensors’ sensitivity differences be kept to a minimum.
Normally, the measured sensitivities between cable extension transducers can vary by up to 3.4 percent, in rare cases. This is mainly due to variations in the electrical angle of the potentiometers, and tolerances of machined mechanical parts.
For most applications, this variance is acceptable - but not in the aerospace industry, where accuracy and exactitude are paramount to all systems and operations. Celesco was able to bring down the sensitivity variance (interlinearity) to Airbus’s requirement of 0.4 percent of full stroke.
In addition, Celesco added a spring loaded cable guide for the 20- and 40-inch units, to give Airbus an added safety margin when attaching and reattaching their Celesco test units. This guide allows for limited, “free release” of the cable without risk of damage caused by high-velocity cable releases.
A special electrical connection was included in the design to accommodate Airbus’s test equipment. Airbus was focused on utilising the Souriau connectors that they had used in other applications, and had a familiarity with.