Incident Overview
A pilot reported an in-flight incident involving violent shaking of the aircraft during a descent. The event occurred approximately 10 minutes after the pilot encountered light to moderate turbulence while cruising at an airspeed of about 150 mph. The pilot initiated a 1,000 foot per minute descent about 15 nautical miles northwest of the airport, with an indicated airspeed between 170 and 180 mph. During the descent, the aircraft began to shake violently. The pilot responded by applying equal pressure to the rudder pedals, pulling out the throttle, and pitching up the nose to slow down. This action caused the shaking to stop. The pilot then continued the descent to landing without further incident.
Post-Flight Inspection
During a subsequent inspection of the airframe, wrinkles, creases, and compression signatures were found in the skin on both the left and right sides of the empennage, specifically from fuselage stations (FS) 233.5 to FS 272. The skin had pulled away from five rivets located on the bottom of the empennage along the left side, forward of FS 256.9. Additionally, the skin from left to right side pulled away from all of the empennage bottom rivets at FS 256.9. On the right side, the skin pulled away from six rivets forward of FS 256.9. The two longitudinal rivet rows on the bottom had skin pulled away from seven rivets on the left side and six on the right side.
Compliance and Operating Limits
All applicable Airworthiness Directives (ADs) had been complied with at the time of the incident. No AD speed restrictions were in effect for this model aircraft. The normal operating range for the aircraft model is between 66 and 175 mph.