LAX04LA253 · Anderson Harmon Rocket II

The airplane collided with a residence following an in-flight separation of the vertical stabilizer, elevator, and upper rudder, which resulted in an uncontrolled descent. The pilot, who was also the builder of the airplane, was on an instrument flight. While established in cruise flight at an elevation of approximately 5,000 feet mean sea level and 200 knots, radar contact was suddenly lost when the airplane entered a rapid descent. Review of the aircraft's radar data revealed primary radar returns were located near the aircraft's mode C returns near the time of the upset. Aerial and ground searches using trajectory data analysis on the primary radar returns commenced; however, no additional components were located. During a post-accident examination of the wreckage, investigators were unable to identify the stabilizer. The day prior to the accident the pilot indicated that he was experiencing control problems with the elevator trim system on the airplane. A manufacturer of another experimental aircraft kit, similar in design to the accident airplane kit, performed structural testing of his kit. These tests indicated that the flight loading could exceed the structural strength of the horizontal and vertical stabilizer control surface so modifications were made in his model to increase the structural strength. These structural modifications were not completed in the accident airplane, nor were they required. There is no requirement for experimental aircraft manufacturers or kit suppliers to analyze the structural integrity of the airplane throughout its operating envelope, nor does a builder have to establish the adequacy of the design during flight tests. The pilot's immediate family had a history of sudden death due to aneurisms and heart failure. Due to the circumstances of the accident, no usable medical data could be obtained to discern the pilot's medical condition at the time of the accident.

Verbatim NTSB analysis and probable cause from the NTSB dataset