On May 01, 2026, at 1604 eastern daylight time, a Beechcraft C23 airplane, N18516, was substantially damaged when it was involved in an accident near Bangor, Maine. The private pilot and flight instructor were uninjured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 instructional flight. According to the certified flight instructor (CFI), the purpose of the flight was to provide instruction to the private pilot in preparation for his commercial certificate. The CFI reported that the private pilot completed the preflight inspection with no discrepancies noted. After engine start, there was some momentary engine roughness; however, it did not last long, and the pilots continued with the lesson. Taxi, pretakeoff checks and departure from runway 33 at Bangor International Airport (BGR), Bangor, Maine, were normal. The CFI reported that during the initial climb, about 200 ft above ground level, the pilot’s door “popped open.” The CFI contacted air traffic control (ATC) and advised that they would need to return to land to secure the door. After returning to the airport and securing the door, they taxied back to the runway for departure. The CFI continued that, after receiving a takeoff clearance, the pilot taxied into position, applied full power, and they departed from runway 33. About 700-800 ft above mean sea level, they made a right turn to a heading of 020° and leveled the wings. The airplane subsequently began to vibrate and run rough. They elected to return to BGR. During the return, the CFI reported that the engine roughness intensified, followed by a total loss of engine power. The CFI assumed control of the airplane, declared an emergency to ATC, and maneuvered toward the runway. While overflying the runway, the CFI realized they were too high and added flaps and slipped the airplane in an effort to lose altitude; however, the airplane floated down the runway. After touchdown, insufficient runway remained to stop. The airplane overran the runway, entered the safety area, and impacted an embankment, which resulted in substantial damage to the right wing and fuselage. The airplane was retained for further examination.