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auxiliary power unit

British  

noun

  1. an additional engine fitted to an aircraft to operate when the main engines are not in use

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Example Sentences

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On the island, Laczko waited as mechanics tried to fix the plane’s auxiliary power unit that sits in the tail of the plane.

From The Wall Street Journal • Dec. 22, 2025

During maintenance work technicians Umit Atas and Luciano "Lucky" Ferriera spotted two pairs of eyes from inside the exhaust of an auxiliary power unit.

From BBC • Jul. 27, 2021

Federal Aviation Administration spokesman Allen Kenitzer says the blaze was in the airliner’s auxiliary power unit and was extinguished with the plane’s fire suppression system.

From Seattle Times • Feb. 12, 2018

A Southwest Airlines plane was evacuated at John Wayne Airport on Monday night after a fire in the aircraft's auxiliary power unit, officials said.

From Los Angeles Times • Feb. 12, 2018

Despite the strength-sapping strain of working under four gravities of acceleration, they managed to get the auxiliary power unit into operation.

From Islands of Space by Campbell, John Wood