Flight Details
The pilot reported that during the flight, he climbed to 7,500 feet and set the power for a cruise speed of 160 mph. To remain clear of clouds, he initiated a descent to 6,500 feet. During the descent, the airplane encountered light turbulence, and then began to vibrate and shake.
Pilot Actions
The shaking persisted for 10 to 15 seconds. The pilot then pulled back on the throttle, and the vibration ceased. Believing the vibration to be engine-related, he reapplied power for cruise. However, the airplane began to shake again, more violently than before. The pilot subsequently reduced power and landed the airplane.
The airplane's never exceed airspeed (Vne) was 203 mph, and the maximum cruise airspeed (Vno) was 160 mph.
Inspection Findings
Post-flight inspection of the airplane revealed extensive damage to the aft fuselage between fuselage station (FS) 256.9 and the 233.5 bulkhead. The longerons were bent downward, and two stringers were cracked. The left and right side fuselage panels below the stabilizers exhibited 45-degree buckling from the bottom of the FS 256.9 bulkhead to forward of the stabilizer cuffs. The bottom fuselage panel had popped rivets and torn skin. Additionally, there were two 2-inch creases in both stabilizers. No pre-existing cracks were found on the longerons, and the ruddervators were properly balanced.