Cessna 210 Hard Landing Caused by Flight Control Interference (N3738Y)

Accident Description and Control Issues During a descent, the pilot reported that extreme pressure was required to pull back on the controls to level the airplane. The pilot was unable to maintain altitude and continued on a straight-in approach to the airport. During the landing flare, the pilot could not pull the control yoke far enough to round out, causing the airplane to land hard on the nosewheel and come to rest off the side of the runway. A post-accident flight control check revealed that the controls could only be deflected aft to the level flight position. After the horizontal situational indicator (HSI) was removed from the instrument panel, the flight controls could be deflected to their full aft position. Examination of the control stop on the control column tube showed significant chaffing marks and black paint transfer on its upper surface. The rear casing of the HSI displayed similar chaffing marks and an indentation consistent with the shape of the control column stop on the lower edge of the instrument. The instrument panel had five shock mounts, of which the lower right and lower center mounts were broken, and the upper left mount was not attached. The shock mounts were fractured through their elastomeric center sections on one end, with large gaping cracks on the opposite end and numerous smaller circumferential cracks through the center sections. Maintenance logbooks indicated that the HSI was installed on August 17, 1994, by an avionics facility to replace the original directional gyro (DG) instrument. The Cessna 210 Service Manual states that the service life of shock-mounted instruments is directly related to adequate shock-mounting of the panel, and that if removal of the shock-mounted panel is necessary, mounts should be checked for deterioration and replaced as necessary. Detailed examination revealed that the shock mounts were the original shock mounts installed in the airplane in December 1963.