On 13 April 1941, all Manchesters were temporarily grounded due to a higher than expected number of engine bearing failures; on 16 June 1941, a second grounding of the type was ordered due to continuing engine troubles. The unserviceability of the Vulture engine forced squadrons to make use of obsolete bombers such as the Handley Page Hampden in its place. Upon the restart of operations in August 1941, additional issues with the aircraft were encountered; the problems included excessive tail flutter, hydraulic failures, and faulty propeller feathering controls. Production of the Manchester was halted in November 1941, by which point a total of 209 aircraft had entered service with the RAF. A total of eight bomber squadrons were equipped with the type, it also served in two further squadrons and also saw use by RAF Coastal Command.