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Position Pick-off Unit (PPU)

The PPU is used in Slat-Flap operating systems for detection of asymmetric operations of flight control surface systems, monitoring speed of operation and providing a position feedback. The input shaft of the PPU drives a Harmonic Drive® Gear, reducing the multiple input revolutions to an angular movement of the sensor, always less than 360°, and free of backlash. TE’s redundant sensor arrangement then converts the position information into electrical signals, sending this data to the Slat and Flap control computer.

Partner of aviation industry

TE Connectivity Ltd. (TE) is a global manufacturer of electrical interconnect solutions. TE’s Aerospace, Defence & Marine Business Unit (AD&M) designs & manufactures ruggedized electromechanical components, connectors, relays, power management, wire & cable and sensors for operation in harsh environment applications. TE develops customized angular position sensors for primary and secondary flight control systems for commercial aircraft. For these sensors, called Position Pick-off Units (PPU), TE AD&M incorporates technology from Harmonic Drive AG.


The standard series

The HFUC-2A Series Component Sets are available in fifteen sizes with gear ratios of 30, 50, 80, 100, 120 and 160:1 offering repeatable peak torques from 1.8 to 9180 Nm and a power density of up to 420 Nm/kg.

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Maintenance-free – for the aircraft life

These sophisticated measurement applications are performed under extreme environmental conditions, such as those found on exterior wing positions. In this environment, the PPU will experience temperature variations from -55 to +90° C, along with extreme vibration and shock loads. Nevertheless, the PPU's are required to provide maintenance free operation throughout the lifetime of the aircraft.

More than 40.000 Gears in action

Gears from Harmonic Drive AG with various reduction ratios, are used in almost all TE PPUs. Since the maiden flight, more than 40.000 Harmonic Drive® Gears have been applied in PPUs and these have been service now for more than 25 years. The next TE PPU, which uses the latest Harmonic Drive® Gear technology, is currently in development. This device will be smaller & lighter than its predecessors, enabling efficiencies in the next generation of commercial aircraft.