Citation 500 Eagle

Helpful hints in identifying High Turbine Blade Failure in flight on the JT15D-1A. The other day a customer of ours was flying from Miami Florida to Trujillo Peru. He and the co-pilot were flying at 28K feet engine parameters were normal and matched. Airspeed was acceptable for the Citation:) Anyway, suddenly the left engine N1 dropped 35% and the airspeed immediately fell 75kn The pilots observed nothing but a N1 drop on the #1 engine and airspeed reduction other parameters WF, ITT, N2, were not affected they started their decent and the power began to improve not considerably but improved slightly there was still very little throttle reaction. Once they arrived at Trujillo we began discussing what might have happened buy telephone. We could not immediately identify the problem although we were thinking it must be a fuel delivery problem FCU,Flow divider something of that nature. I dispatched a mechanic with a spare FCU, Fuel pump and flow divider as well as a Bore scope to inspect the internal components of the engine.It turns out that a high turbine blade liberated itself from the disk and caused all kinds of havok down stream although very little visible damage from the tail pipe just forward of the third stage T-Wheel was all the evidence we needed.