Surveillance Australia operates a fleet of 10 Bombardier Dash 8 aircraft across Australia and needed a fuel level sensor for the range-extending cabin mounted fuel tanks, to replace failing float type.
To provide the maximum range and flying time, the aircraft are fitted with cabin-mounted, cased-bladder type fuel tanks. The replacement sensor had to fit and install in the existing aperture, which required a lightweight, robust sensor designed for an inverted installation and fully sealed to prevent any fuel leaking through the sensor.
The sensors also had to be available on short delivery lead times to fit in with the availability of the aircraft in their flight programmes for maintenance work.
Using solid-state capacitive level sensor technology, a solution developed to meet the mechanical installation and product reliability characteristics was confirmed.
A custom design was produced with a 5-hole mounting flange with integral 'O'-ring seal. A fully sealed and potted internal construction ensured no fuel leak paths were possible in its inverted installation orientation. A military specification 6-pin connector guaranteed reliable and secure connection.
With a probe length of just under 1 metre, additional mechanical features were included to enhance the mechanical integrity and reliability of the sensor. Due to the tight timescales involved, the customer took responsibility for the flight approvals process under their '21 Step' procedure.
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