The CH-34 was also built and developed under license from 1958 in the United Kingdom by Westland Aircraft as the turboshaft engined Wessex which was used by the Royal Navy and Royal Air Force. The RN Wessex was fitted out with weapons and ASW equipment for use in an antisubmarine role. The RAF used the Wessex, with turboshaft engines, as an air/sea rescue helicopter and as troop transporter. Wessexes were also exported to other countries and produced for civilian use.
Oxenford, Andrew. Reflections of an Oil and Gas Helicopter Pilot (p. 11). Sabre & Quill. Kindle Edition.Early in 1974, a cargo vessel was inbound from the USA with nine new, 26-seater Sikorsky S-61N helicopters as deck cargo. BEA Helicopters (part of British European Airways before it merged that year with British Overseas Airways Corporation - BOAC to form British Airways) had ordered them. Controversially, when the vessel arrived, the Minister of Aerospace and Shipping, Trade and Industry directed the helicopters to a private enterprise - Bristow Helicopters Ltd (BHL). And Bristow needed pilots to fly them. At 27, with a recently completed fixed-wing commercial pilot’s licence with instrument rating (CPL IR) – the latter flown in a Cessna 310 twin, September 1974 was still not a good time to apply for work with the airlines. Conversely, commercial helicopter operations in the Oil & Gas industry were promising. And Bristow Helicopters had recently begun courses to convert airline pilots to fly this bonanza of helicopters. Though only a budding airline pilot, I was invited to an interview at their Redhill HQ in October. The apologetic receptionist advised me the meeting was off, though she gladly reimbursed my travel expenses from South Devon. They will be in touch. Meanwhile, if I was interested in helicopters, I was welcome to look around them in the hangar. It could have been more encouraging. Packed inside like sardines in a tin were seven Sikorsky S-58 helicopters. They were former German Army Aviation Corps machines, part of the fleet their government had disposed of between 1972-1974. Speaking to an avionics engineer, Steve Hogarth, who went on to become my pilot manager, he explained they would be upgrading them. They will remove the double-banked Wright Cyclone piston radial engines and replace them with a kit developed by Sikorsky: Pratt and Whitney twin pack PT 6T3 turbine engines mated with a combining gearbox (C-Box), similar to the configuration on a Bell 212. Fitted with an additional fuel tank on the port side, they become S-58ETs. The power assurance performance figures were disappointing when they air-tested the first one to be converted. The Sikorsky rep commented, “Oh, we thought that might happen.” Alan Bristow, aka Big Al, was not impressed. “Who advised me to buy these (expletive) things?” Prophetic? Two years later, an accident destroyed one on the North Sea. G-BCRU.
https://assets.publishing.service.gov.u ... G-BCRU.pdf
I recommend this recommendation to all the heli-heads here... (so in effect to anybody who cares about aviation)...