MIA02LA010 · Beech 58

The pilot stated that after the initial takeoff, the cabin door "came ajar." The flight returned and landed uneventfully where he closed the cabin door. The flight again departed and the cabin door "came ajar again." The flight returned and the airplane was landed, "...with the landing gear up." Postaccident examination of the airplane revealed the landing gear warning system was inoperative. The microswitch for the left throttle/gear warning system was shorted internally and the roller arm was bent backwards. The microswitch for the right throttle/gear warning system was not making contact with the throttle cam; buckling of the throttle attachment plate was noted. Manual operation of the microswitch of the right throttle/gear warning system would trip the circuit breaker. The left microswitch was removed from the circuit and manual activation of the microswitch of the right throttle/gear warning system activated the gear warning system. Examination of the cabin door revealed that when the cabin door was closed and latched, the outside door handle was extended away from the door approximately 1.5 inches; a rusted and broken spring was noted. Operational check of the door latch mechanism was accomplished revealing no binding noted; the door locked. The upper latch was found to go over center with the door latched and the aft latch bolt "...locked properly." The two rivets that secure the pin guide assembly to the door were found broken. There were no written discrepancies pertaining to the cabin door between May 25, 2000, and September 7, 2001. During that same time frame, one discrepancy related to the gear warning system was noted. The entry indicates that the throttle warning horn circuit breaker popped during descent to land prior to having the landing gear extended. Airworthiness Directive (AD) 97-14-15, effective date of September 2, 1997, applicable to the accident airplane, to prevent unintentional opening of the cabin side door and the utility door from the interior of the airplane, was complied with on October 4, 1997. The airplane had accumulated approximately 1,281 hours at the time of the accident since compliance. Further review of the maintenance records revealed that the airplane was inspected last in accordance with a 100-hour inspection that was signed off on September 17, 2001; the airplane had accumulated 38 hours since the inspection at the time of the accident. Review of the inspection guide for the airplane indicates that the cabin door is inspected for security of attachment and the latching mechanism is checked for proper engagement and ease of operation.

Verbatim NTSB analysis and probable cause from the NTSB dataset