The Rolls-Royce Turbomeca RTM322 engine was selected to power the WAH-64 Apache Attack Helicopter, for the Army Air Corps, by the UK MoD in 1996. Integration of this new engine installation was to be conducted remotely, at the Boeing facility in Mesa, Arizona. It was recognised, from the outset, that engine control system integration with the rotor drive-train would be a risk item in the overall programme. By their nature, helicopters have an established reputation for challenging dynamic system characteristics and the Apache is certainly no different. On top of this, the declared two year time-scale of this flagship 'Smart Procurement' programme was seen to be very aggressive. Despite extensive use of sophisticated computer simulations, it was anticipated that engine control system optimisation would be necessary during the flight test programme. The traditional method of revising control laws was seen to be too time consuming so a new process, utilising the on-line development capability of the RTM322 control software, was defined. This was further exploited by building flexibility into the control algorithms so that desired functional options could be set up via a computer link. Gaining flight clearance for this process was a major achievement. The flight programme commenced in 1998 and, as anticipated, several control integration issues were soon identified. Each was addressed by implementing incremental software solutions using the defined process. This method enabled the baseline aircraft flight programme to progress without interruption. During 20 months of flight testing we used this software revision process several times, resulting in the delivery of an exemplary standard of engine control for the WAH-64 Apache, on time, in June 2000.
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