The 2.111 models differed significantly in details from Heinkel's wartime He 111H design while using essentially the same airframe in appearance, featuring heavier armament and eventually Rolls-Royce Merlin engines.

[2] Setting up production was slow, with relatively little support received from Germany as World War II continued.

[5] Following the end of the war, access to new German-built Junkers engines and parts became impossible, and CASA found an alternative with the Rolls-Royce Merlin 500.

In April 1956, 173 Merlin engines were ordered and installed on the aircraft[6] in a "power plant" nacelle of a type originally developed by Rolls-Royce for the Beaufighter II and later used on the Avro Lancaster.

Eyewitness reports indicate the aircraft lost power to one engine on final approach and ploughed through a chain link fence before colliding with a building under construction.