contracting for the Ministry of Transport, and Bain's personal arguments that cost-plus contracts be used as a ward against budget overruns, TCA's contract with Avro demanded fixed prices for the entire development, as well as a fixed price for the aircraft of C$350,000. Additionally, Avro was not allowed to sell the aircraft to any other airline for three years. After that period, if a buyer paid less than C$350,000 for the aircraft, Avro would have to pay the difference to TCA. Furthermore, during the testing period of one year after the first aircraft was introduced, Avro would have to pay all costs, even if paying passengers were carried. Jack Dyment, chief of TCA's entire engineering department, suggested that Avro pay for the testing so that it would "permit us to learn how to successfully operate a jet aircraft without having to pay for such experience the hard way." Design changes In 1947, Fred Smye, president of Avro, advised Herbert James Symington of TCA that they could not meet the fixed price contract. Symington's response was to pull out of the project. C. D. Howe stepped in and offered $1.5 million to continue the project, at a slower pace. At about the same time, Rolls-Royce told Avro that the civil certification of the Avon could not be guaranteed in time for the Jetliner's rollout. This, in turn, would lead to higher operational and maintenance costs. Nevertheless, Avro continued with its plan to build the jet, selecting four Rolls-Royce Derwents to replace the two Avons. Chief Designer James C. Floyd was upset by these developments, but in the end found a number of advantages to the four-engine layout. The main advantage was that in an engine-out situation, the aircraft would lose only a quarter of its thrust, rather than half. In particular, the asymmetry in thrust originally called for a powered rudder to correct for yaw in the case of an engine failure, but with four engines it was found yaw was so small it could be corrected easily with just the manual trim controls. Although bearing some resemblance to the jet-powered Avro Tudor 8 and 9 (the former flying on jet power in 1948 and the latter becoming the experimental Avro Ashton first flying in 1950), Floyd's design was conceived from the outset as a commercial jet airliner. The updated design was presented in October 1948, and in February 1948 TCA