What was found
ABOUT 15 SECONDS AFTER TAKEOFF, ENGINE BEGAN TO RUN ROUGH AND LOSE POWER. PILOT COULD NOT MAINTAIN ALTITUDE, AND MADE AN UNEVENTFUL LANDING. INSPECTED ENGINE, FOUND NR 5 PISTON BROKEN AND NO LONGER IN THE CYLINDER; ALSO, A 2 INCH CRACK FROM BASE OF NR 5 PISTON LEADING UP TO BACK BONE OF CASE.