Why did the A109 go from one engine to two?

Short answer

Because of the market: the design team came to recognise that a twin-engined helicopter was found more attractive, so the project was revised in 1969. Compared with the Bell 206, then the market leader, the A109 offered higher top speed, engine redundancy and more seats.

Published: November 1, 2026 · Updated: November 1, 2026 · Edited by Above Ten Thousand · Editorial policy

Why did the A109 go from one engine to two?

Hiller Model 1031 A-1 Flying Platform

A project revised in 1969

The decision came from the market: the design team came to recognise that a twin-engined helicopter was found more attractive, so the project was revised in 1969. On 4 August 1971, the first of three prototypes made the type's maiden flight.

The advantages of the twin engine

Compared with the then market leader, the Bell 206, the type offered several advantages: higher maximum speed, the redundancy of two engines and greater seating capacity. At first, the A109 was marketed under the name "Hirundo," the Latin term for swallow, a designation dropped after a few years.

The manufacturer

The Società Costruzioni Aeronautiche Giovanni Agusta was founded in 1907 and built aircraft until 1943. After the Second World War and the death of Count Agusta, Countess Agusta and her sons Domenico, Vincenzo, Mario and Corrado founded Meccanica Verghera Agusta in 1945, in Verghera, Gallarate, Italy. In 1952 the firm acquired a licence to build Bell Model 47 helicopters. From that beginning, Agusta went on to become a major helicopter design and manufacturing company.