Editing Aeroelasticity (section)

==== Propeller whirl flutter ====
''Propeller whirl flutter'' is a special case of flutter involving the aerodynamic and inertial effects of a rotating propeller and the stiffness of the supporting [[nacelle]] structure. Dynamic instability can occur involving pitch and yaw degrees of freedom of the propeller and the engine supports leading to an unstable precession of the propeller.<ref>{{cite web |url=https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19670020798.pdf |first=Wilmer H. |last=Reed |title=Review of propeller-rotor whirl flutter |date=July 1967 |publisher=Nasa |access-date=2019-11-15}}</ref> Failure of the engine supports led to whirl flutter occurring on two Lockheed L-188 Electra aircraft, in 1959 on [[Braniff Flight 542]] and again in 1960 on [[Northwest Orient Airlines Flight 710]].<ref>{{cite web |title=Lessons Learned From Civil Aviation Accidents |url=https://lessonslearned.faa.gov/ll_main.cfm?TabID=2&LLID=7&LLTypeID=2 |access-date=2019-12-14}}</ref>