Accident Overview
On April 30, 2017, at approximately 1330 eastern daylight time, a Piper PA32RT-300, registration N31678, was substantially damaged during a forced landing near Coral Springs, Florida. The airline transport pilot and a pilot-rated passenger were not injured. The personal flight was conducted under 14 CFR Part 91 in visual meteorological conditions with no flight plan filed.
Sequence of Events
According to the pilot, during cruise flight he noticed a drop in engine manifold pressure. Advancing the throttle forward yielded no engine response. The engine continued to run smoothly at reduced power, but the pilot could not maintain altitude. After several unsuccessful attempts to increase power, he declared an emergency and executed a forced landing on a levy. During the landing roll, the airplane veered off the levy and collided with a ditch.
Post-Accident Examination
A Federal Aviation Administration inspector examined the wreckage and found the aft right wing spar damaged. Inspection of the throttle body fuel injection servo revealed that the throttle cable linkage attachment was disconnected from the throttle body. The throttle cable itself operated smoothly without binding and moved freely when opening and closing the throttle position.
The fuel injection throttle body servo was removed for further examination. The throttle linkage was found loose at the attachment point of the servo. The castle nut and cotter pin were installed, but the castle nut was loose, preventing the throttle linkage teeth from making full contact with the servo linkage teeth that control the butterfly valve. Manual operation of the linkage showed it slipped because the gear teeth were not tightened completely. The throttle linkage gear teeth were worn with flat spots, as were the throttle body linkage gearing teeth.
Maintenance History
According to the airplane's maintenance records, the engine was most recently overhauled in June 2014, at which time an overhauled throttle body fuel injection servo was installed. The aircraft subsequently underwent annual inspections in August 2015 and September 2016. However, the maintenance log entries for those inspections did not explicitly mention inspection or maintenance of the throttle body fuel injection servo.