20001127041639A

(-23) The upper engine cowling departed the airplane just after takeoff from runway 29. The cowling subsequently struck the right windshield, right baggage door, and right side of the horizontal stabilator. The pilot-in-command (PIC) subsequently executed a left turn onto a left downwind leg, and returned to land on runway 29 without further incident. Post-accident inspection of the airplane revealed that aft-displacement of the right side of the horizontal stabilator during cowling impact had resulted in crush damage to the left side of the tail cone structure. The damage was located just forward of the stabilator attachment fitting assembly, between the bulkhead assemblies at stations 156.00 & 191.00. Other damage included the right stabilator tip and leading edge, and the right windshield. During a post-accident interview, the PIC reported that he had performed a pre-flight inspection of the aircraft just before the flight and that the cowling appeared to be secured at that time. Just after takeoff, he observed the cowl "shudder" briefly, then suddenly depart the airplane. When asked if he or anyone else had recently removed the cowling for any reason, the PIC stated that he hasnever removed the cowling for any reason, and that no one else had recently removed the cowling to his knowledge. The PIC also noted that he had flown the airplane for about 1.5 hours earlier in the day, and that he did not experience any problems during that flight. During a separate interview, the owner/operator of the FBO where the aircraft was based reported that the pilot had washed the airplane at the airport 5-hangar wash rack just before the flight. Examination of the four upper cowling fastener assemblies (Piper p/n 65202-05) revealed that three of the four fastener assembly studs (Piper p/n 487719) were missing. The remaining stud was located on the left, rear fastener assembly, and was held in place by a retainer ring. (According the FBO owner/operator, the wash rack was searched for the missing studs after the mishap, and none were found there). The upper cowling was damaged primarily around the nose/intake area. The forward reinforcing composite structure (normally bonded to the interior of the curved leading edge around the cowl air intake) had separated from the cowling and was broken into four pieces. This structure contains the cowl alignment pins, and there was noevidence of abnormal were between the cowl pins, or the pin receptacles located on the lower cowling. Closer examination of the remaining cowl latch fastener stud and associated receptacle revealed some evidence of wear: an operational test of the fastener revealed that while the stud positively engaged the receptacle when turned 1/4 turn clockwise, some looseness ("play") remained between the fastener and the associated receptacle. The tip of the stud was polished, but did not appear to be excessively worn as compared to a new stud, though. Also, tactile inspection of all four of the receptacles in the lower cowling interior did not reveal any obvious evidence of damage or abnormal wear. Based on the aircraft maintenance logs, the last maintenance requiring cowling removal occurred ten days before the mishap. Elapsed operating time since then was about 7 hours.