As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CAPTAIN WAS IN FUNCTION AND DURING TAKEOFF, SEAT MOVED SUDDENLY BACKWARD .THE ACFT ATTITUDE PITCHED UP AND SPEED DECREASED. CONTROL WAS GIVEN TO F/O THAT STABILIZED ACFT AND RESUMED NORMAL CLIMB. AFTER INSP, THE 2 SEAT LOCKING SPRINGS WERE FOUND BROKEN.