North American TB 25N accident near Dallas, Texas, October 29, 2016

The NTSB's narrative final · quoted from the NTSB record

The airline transport pilot reported that the twin-engine, historic airplane was flying about 155 mph and 1,000 ft above ground level. Upon entering the left downwind leg of the airport traffic pattern, the pilot extended the landing gear. While the gear was in transit, the crew felt a jolt, as if a bird had impacted the front of the airplane. The pilot made a normal landing, parked the airplane, and noted damage to the left horizontal stabilizer and elevator. A crew from another airplane reported to the pilot that they observed an object depart the accident airplane during landing gear extension. A postaccident examination revealed that the left inboard landing gear door separated in flight and impacted the engine nacelle, left horizontal stabilizer, and elevator. The landing gear door was later found in a residential neighborhood about one mile north of the airport. The gear door was equipped with two arresting cables that were intended to prevent the door from hyperextending. The arresting cables were not installed in the correct position, and the investigation could not determine how long the arresting cables had been incorrectly installed. The landing gear door connecting rod was bent and fractured into two pieces at the safety wire drill hole. The fractured connecting rod was consistent with an overstress failure in bending. If the arresting cables had been installed correctly, it is likely that the landing gear door would not have separated from the airplane when the connecting rod failed.

The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.