What was found
(CAN) DURING GROUND HANDLING, CABIN DOOR WOULD NOT REOPEN AFTER ACFT HAD BEEN TOWED. MAINTENANCE FOUND THE UPPER AFT BAYONET BROKEN, WITH THE BLADE STILL ENGAGED IN THE DOOR FRAME. THIS IS A CHAPTER 4 CYCLE LIMITED ITEM WITH 3851 CYCLES SINCE NEW, 5000 CYCLE LIMIT. FAILURE MAY HAVE BEEN DUE TO AGRESSIVE HANDLING, SLAMMING, OF THE DOOR DURING GROUND HANDLING.