Patent ID: 7878759

Claim:
A method for limiting stress levels in an aircraft-powering turbofan assembly by controlling unstable movement of laminar-to-turbulent boundary layer transition on fan blades of the turbofan assembly during aircraft flight, said method comprising: including on a flying aircraft, an aircraft-powering turbofan assembly comprising multiple fan blades mounted on a fan disc and each of said fan blades having a leading edge, a trailing edge, and two side surfaces that comprise a high-pressure side surface and a low-pressure side surface, each blade also having a relatively long chord length, said turbofan assembly being configured such that a laminar-to-turbulent boundary layer transition range occurs on the low-pressure side surface of each of said fan blades during flight; providing a plurality of said fan blades each with a laminar-to-turbulent boundary layer transition control feature at the low-pressure side surface of the respective fan blade, positioning each said control feature on the respective blade at a position that will initiate and positionally stabilize the laminar-to-turbulent boundary layer transition to a location upon the respective fan blade between said control feature and the respective fan blade's trailing edge that will substantially maintain an aggregate limited stress occurring in the turbofan assembly at a mounting of the respective fan blade to the fan disc to below fifty megapascals during flight within the aircraft's operating envelope.