Introduction
On March 18, 2021, at about 1427 mountain standard time, an experimental, amateur-built Lancair Evolution, registration N469KS, was substantially damaged in an accident near Phoenix, Arizona. The pilot, who was the sole occupant, was not injured. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a personal flight.
Accident Narrative
According to the pilot, after departing from Falcon Field Airport (FFZ) in Mesa, Arizona, on an instrument flight rules flight plan, he began a climb. As the airplane passed through 22,000 feet mean sea level, approximately 30 nautical miles west of the departure airport, the cabin door separated from the aircraft. The departing door struck both the horizontal and vertical stabilizers. The pilot diverted and landed without further incident. Photographs taken by the pilot after landing revealed substantial damage to the left horizontal stabilizer. The cabin door was not recovered.
Aircraft and Door Mechanism
The airplane was equipped with a single 42-pound main cabin door located on the left side of the cockpit. The door was attached by two hinges at the top of the door frame and secured the pressurized cabin via eight latches: three at the lower frame, two on the front door post, and three on the rear door post. Each latch mechanism consisted of a steel latch arm and ball attached to an aluminum latch body, which was bolted to the door. When the door was closed and locked, each latch arm and ball aligned and connected with its respective socket at the steel latch anchor attached to the door frame. A single handle operated the locking mechanism; rotating the handle clockwise locked the door by engaging the anchors through a series of sprockets and chains, while rotating it in the opposite direction unlocked the latches.
Previous Incidents and Manufacturer Actions
According to the kit manufacturer, two previous main door failures had been reported. The first occurred in 2010 on another airplane when a latch was not aligned over center and failed to secure, causing adjacent latches to carry the load and one to fail at the aluminum latch body. The second failure occurred in November 2020, resulting in an explosive decompression during cruise flight when the lower rear latches were not secured. The manufacturer attributed the cause to a failure of the lower rear latch to secure before takeoff, leading to overstress and failure of forward latches in a domino effect. Following the 2020 incident, the manufacturer issued an inspection advisory requiring an inspection of the main door latches for cracks or other physical damage within the next 10 hours of flight. This advisory was issued to maintenance facilities approximately three months before the accident airplane received its most recent service. The airplane's maintenance logbooks did not indicate compliance with the advisory, and the maintenance facility that regularly serviced the airplane reported they were not aware of it.
Examination
An examination of the accident airplane's fuselage frame by a Federal Aviation Administration inspector revealed no damage to the hinges or latch anchors.
Post-Accident Service Bulletin
Although the main door was not recovered, the airplane manufacturer issued a service bulletin on April 20, 2021, requiring inspection of the latch mechanism to ensure that all eight latch balls seated properly within their sockets without any clearance. Additionally, the bulletin required inspection of the hinges at the next condition inspection and replacement of the aluminum latch bodies with structural stainless steel alloy bases.