That happened a lot with our EC-135N airplanes on max-weight takeoffs, but we got used to it. When we merged with the unit at Wright-Patterson, their guys said: "Something's not right here." A series of instrumented tests revealed that the "book" was off by as much as 15%, because the performance engineers had only estimated a drag penalty for the modified nose. Fortunately, nobody had lost an engine during a max-weight takeoff.