Final Report: UK AAIB FINDS NO CLEAR PROBABLE CAUSE
Reims Cessna F406, Inverness, Scotland, Oct. 22, 2004–The pilot of G-TWIG was positioning empty to Inverness. All was normal until he started his letdown, when radar recordings showed an unsteady rate of descent, as well as a track deviation, then radar and voice contact was lost. The wreckage, found more than 24 hours later on high ground, indicated an impact speed of about 350 knots, and marks implied that the aircraft was banked to the left. There was no sign of pre-impact primary or secondary control failure or powerplant failure.
Investigation of the pitch-trim system showed that the trim actuators were nearly fully nose down rather than the calculated 0.125 inches from the full nose-down position appropriate to the calculated weight-and-balance. The British Air Accidents Investigation Branch (AAIB) reported that it was not possible to find sufficient evidence to allow a firm conclusion of the cause. It repeated in its report its previous recommendation that this class of aircraft be required to be equipped with an FDR and CVR.