Air Transport World

Those 'squawking' black boxes. (position sensing devices)

Bothered by high return rates of "black boxes" in which no faults could be found, an airline supplier has sparked what promises to be a revolutionary new method of correcting the "nuisance squawks" that cost carriers millions of dollars in wasted maintenance time and excessive spares inventories. Among the products manufactured by Eldec Corp. are proximity switch electronics units (PSEUS) for virtually all transport aircraft. These devices typically communicate to cockpit gauges and fault displays the responses of 100 or more inductive sensors that detect the positions of moving components such as doors, landing gear and control surfaces.

When pilots report erroneous in-flight indications of conditions such as flap asymmetry and the problems cannot be duplicated on the ground, mechanics often try to fix them by replacing the PSEU, says Eldec. But when the device is returned to the manufacturer, it works perfectly. in fact, airlines say no faults are found in wen over half the avionics items removed from aircraft. …

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