BAe Jetstream 3M (C-10A)

Handley Page designed the Jetstream with the American regional and executive market in mind, but powered it with a French engine, the Turbomeca Astazou. To improve its sales prospects in the United States, the fifth prototype was fitted with the US-built Garrett AiResearch TPE-331 turboprop in place of the Astazou. The change was more than commercial: with an American powerplant, the United States Air Force (USAF) could consider the aircraft for light cargo work.

The outcome was a USAF order, placed in 1968, for eleven aircraft with a cargo door and accommodation for twelve passengers or six stretcher cases. In the manufacturer's nomenclature they were the Jetstream 3M; in the US military inventory, the C-10A. The French site aviationsmilitaires.net gives the same figure of eleven HP.137s ordered in 1968, and all-aero describes the contract as a USAF competition for the C-10A transport that the Jetstream won. According to the LOGBOOK production list, all C-10As were to be powered by the Garrett AiResearch TPE-331-3A-301W turboprop.

The same LOGBOOK list makes it possible to follow the airframes of this version one by one. Line number 05, registered G-AWBR and listed as an HP.137 Mk 3M, first flew on 21 November 1968; it was withdrawn from use in October 1969, stored at Radlett, Hertfordshire, and scrapped in May 1970. In addition, G-ATXI, a Handley Page Mk 1 that had first flown on 8 March 1968, was converted to Mk 3M standard in May 1969 and broken up at Radlett in December 1970.

LOGBOOK allocates consecutive USAF serial numbers, from 68-10378 to 68-10392, to fifteen production airframes marked as Mk 3M (constructor's numbers 219, 226, 228, 232, 236, 239, 242, 244, 247, 250, 260, 270, 272, 273 and 277). None was completed or flown. Most were sold for scrap in January 1972; several were scrapped at Radlett itself in 1970, and the airframe allocated serial 68-10382 was not sold for scrap until May 1976. The fifteen serials do not match the eleven aircraft of the order given by the other sources; the discrepancy is left unexplained by the available material.

The USAF cancelled the contract in October 1969, citing late delivery. Handley Page was by then struggling with the Astazou and with a development programme whose cost had risen from a projected £3 million to more than £13 million; losing the military order came at the worst possible moment for the company, which never finished a single C-10A. No aircraft was ever delivered to the Air Force.

The 3M was not a dead end. When British Aerospace, formed in 1978 with Scottish Aviation among its constituents, decided to develop a "Mark 3" Jetstream, it repeated the recipe of the USAF version: replacing the Astazou with more powerful Garrett turboprops offering longer intervals between overhauls. That idea produced the Jetstream 31, which turned what had been a military failure in 1969 into a civil success.