aircraft engine

From Wikipedia: Rolls-Royce plc:

Rolls-Royce plc is a British aircraft engine maker, and the largest in the world[citation needed]. The company has related businesses in the defence aerospace, marine and energy markets.

Rolls-Royce was nationalised in 1971, by which time aircraft engines had long been the most significant part of the business. The automobile company was separated in 1973 and the present Rolls-Royce plc was re-privatised in 1987. Rolls-Royce is, through its defence aerospace division, the world's 16th largest defence contractor.

From Wikipedia: Allison Engine Company:

The Allison Engine Company was a U.S. aircraft engine manufacturer which was acquired by Rolls-Royce plc in 1995 to become a subsidiary, Rolls-Royce Corporation. With the acquisition of Allison, Rolls-Royce expanded its product line to the point where it can now offer engines in virtually all market segments, from helicopters (e.g. AE 1107C-Liberty), to the largest wide-body aircraft (e.g. Rolls-Royce Trent).