Speed Cowl Development History.
Since its introduction in 1989, the Pilatus PC-12 design has become the best selling single engine turboprop. It naturally attracted the attention of American Aviation Inc. a company with four decades of success in making performance enhancing improvements for turbine powered aircraft such as the King Air and Cheyenne airframes. American’s engineering team was tasked to look at the Pilatus design and see if any improvements could be made to that aircraft.
They identified the PC-12 cowling inlet system as an older design, and that the airplane would most likely benefit from a more modern and efficient inlet. Numerous instrumented flight tests of the stock PC-12 confirmed that a new cowling / inlet system could make major improvements.
A new prototype design incorporating cutting-edge technology was developed and flight tested confirming optimum performance could be achieved. The performance improvements were so substantial that the costs to manufacture an all new cowling / inlet system from carbon fiber and obtain FAA and EASA approval could be justified. This lead to the manufacture and FAA certification of the Speed Cowl which combined a cowling inlet with maximum recovery of high-velocity ram air, and internal ducting that was aerodynamically designed to minimize flow losses of high-velocity air to the engine’s plenum. The results were higher available torque at the same ITT settings, which significantly improved the performance of the Pratt and Whitney PT6A-67 turbine engine.
Speed Cowl™ has been flight tested in multiple flight configurations, climb, cruise at various altitudes, descent, with the inertial separator door open and closed—all at varied torque and ITT settings.
The results showed the cruise true airspeeds and climb rates increased significantly in the flight levels, without exceeding any aircraft or engine limitations. The performance improvements naturally depend on the altitude, outside air temperature and ITT settings used. New performance charts are provided due to the increased efficiency of the cowling / inlet system.