What happened
The aircraft was being operated for the first time since undergoing a recent repainting. While the pilot was maintaining cruise altitude, wind noise began entering the cabin. Upon inspection, the pilot observed that the bottom of the emergency exit door was ajar.
Shortly after this observation, the door separated from the fuselage and struck the leading edge of the horizontal stabilizer. Despite the structural impact, the pilot was able to complete an uneventful landing.
The investigation
An examination of the aircraft revealed that the emergency exit had been mis-rigged. Investigators reviewed records from the most recent annual inspection, which noted that the seal for the upper cabin door had been replaced; however, there was no evidence of any work performed on the emergency exit during that inspection. Furthermore, documentation regarding the recent repainting of the aircraft showed no record of any work that would have required the removal of the emergency exit door.