Problems arose as soon as mass production began. Prototype engines had been hand-assembled by Napier craftsmen and it proved to be difficult to adapt it to assembly-line production techniques. The sleeves often failed due to the way they were manufactured from chrome-molybdenum steel, leading to seized cylinders, which caused the loss of the sole prototype Martin-Baker MB 3. The Ministry of Aircraft Production was responsible for the development of the engine and arranged for sleeves to be machined by the Bristol Aeroplane Company from their Taurus engine forgings. These nitrided austenitic steel sleeves were the result of many years of intensive sleeve development, experience that Napier did not have. Air filters had to be fitted when a new sleeve problem appeared in 1944 when aircraft were operating from Normandy soil with its abrasive, gritty dust.