The National Transportation Safety Board (NTSB) just released its preliminary report of the crash of N8930N, a Cessna 310R twin-engine aircraft, shortly after takeoff on April 11, 2025, in Boca Raton, Florida. All three occupants, family members who included an accomplished acrobatic pilot, another certified pilot, and a minor passenger, were fatally injured. The aircraft had been bound for Tallahassee when it struck a roadway near the airport, causing minor injuries to a motorist.
Our hearts go out to those grieving the tragic loss of this family. The preliminary report details the heroic efforts of the pilots for roughly 10 minutes in dealing with what initially appears to be a flight control issue with the rudder of the Cessna. According to the preliminary report, the aircraft was conducting its first flight after its annual inspection was completed. Air traffic control recordings revealed that one of the pilots reported that they were having a problem with the airplane’s rudder and that they could only make left turns.
Preliminary ADS-B data showed that immediately after takeoff, the airplane drifted left, and continued making left 360-degree turns, ultimately crashing on the 9th turn. Inspection of the wreckage showed that both engines were operating at the time of impact. Inspection of the left rudder showed that the rudder cable “was fractured near the rudder pedal attach point and at the rudder bellcrank. The separated cable ends exhibited a splayed, broomstrawed appearance consistent with tension overload separation.” The inspection also showed that trim rod end extension was measured to be 1.5” or a trim setting of 21° that would cause the rudder to be deflected to the left.
These findings explain why the aircraft would not respond to right‑turn inputs and frame the NTSB’s present focus: determining why the rudder remained deflected left.
Rudder Flight Control Aerodynamics
In a Cessna 310R, as in most fixed-wing aircraft, the ailerons, not the rudder, perform the primary turning function. The ailerons are control surfaces located on the wings and are controlled by the control yoke in the hands of the pilot. The ailerons control the roll axis of the aircraft. The pitch axis is controlled by the elevator located on the tail or empennage of the aircraft. The elevator is also controlled by pilot inputs from the control yoke.
The rudder controls the yaw axis, or in other words, where the nose points, either left or right. The rudder is controlled by the rudder pedals at the pilot’s feet. In flight, the rudder is used to assist and “coordinate” the aileron turns. A coordinated turn is one where the bank angle is appropriate for the airspeed and rate of turn, resulting in neither a slip nor a skid.
Depending on the design of the aircraft, the rudder by itself can have varying degrees of effectiveness in causing turns. Most civilian aircraft wings (Cessna 310R included) are designed with dihedral, which is an upsloping of the wing from the wing root. This wing design promotes stability and is generally considered beneficial in civilian aviation. In an aircraft with no dihedral, the application of the rudder would simply cause the aircraft to fly with a “sideslip” or fly crooked in relation to the oncoming airflow, and not have the tendency to cause the aircraft to turn or roll. The airplane would still fly, but not as efficiently.
But if an aircraft is designed with wing dihedral, rudder input alone will cause the aircraft to roll. Aerodynamically, this is called “dihedral effect.” Dihedral effect is defined as a rolling moment due to sideslip. In other words, as the rudder is deflected, the aircraft will not only yaw left or right, but it will also roll without the aid of ailerons influencing the bank angle.
Due to the designed dihedral of the Cessna 310R wing, if the rudder is deflected, the aircraft will turn and roll in that direction. This dihedral effect, among other factors, is what points the NTSB investigators to look at what may have caused the rudder to be deflected, causing the consistent left turns after takeoff until the accident.
Aerodynamically, the dihedral effect caused by a malfunctioning rudder can be counteracted by the application of opposite ailerons as long as there is sufficient airspeed and or low enough angle of attack (AOA) of the aircraft’s wing. The key to overcoming the rolling effect caused by the rudder is ensuring sufficient airflow over the ailerons by maintaining sufficient airspeed or decreasing the AOA, thereby decreasing drag. In this situation, the ailerons are what counteract the rudder’s roll-inducing input. If airspeed slows or the AOA increases so that the airflow is insufficient for the ailerons to keep the wings level, the rudder will overpower the ailerons, and the aircraft will continue an uncontrolled roll, eventually resulting in a crash. The point where the ailerons lose their ability to counteract the dihedral effect is referred to as the “crossover AOA” or “crossover speed.”
Two prominent airline accidents in the 1990s involving Boeing 737 aircraft resulted from uncontrolled dihedral effect below the crossover AOA/speed. The crash of United Flight 585, in Colorado Springs in 1991, killed all 25 people on board, and USAir Flight 427 near Pittsburgh in 1994, killed all 132 people on board. Both accidents occurred while the aircraft were at low altitudes and slow speeds while on approach to landing. In each case, the yaw damper mechanism malfunctioned and produced an uncommanded rudder deflection, resulting in an uncommanded and uncontrollable roll. Because the rudder deflection occurred at such low altitudes and below the crossover AOA and crossover speed, the pilots had little chance to recognize the situation and were ultimately unable to recover control of the aircraft.
The situation that tragically took the lives of those onboard N8930N appears to have the hallmarks of an uncommanded rudder deflection and the resulting aerodynamic effects. It is only based on the heroic efforts of the pilots that they were able to maintain flight for as long as they did in a desperate attempt to return to Runway 5 at Boca Raton Airport.
The NTSB will continue analyzing the rudder system, recent maintenance records, and potential human‑factor issues as it works toward a final report, which is expected within eighteen to twenty‑four months.
Christopher Rusing is an attorney with Aviation Law Group PS (ALG) and is also a current airline captain on the A320 series of aircraft, is a line checkairman, simulator checkairman and has been a simulator instructor qualified to instruct jet upset recovery or extended envelop training (EET) at his airline since such aerodynamic training was mandated by 14 CFR § 121.423.
ALG is a law firm that limits its practice to aviation accidents and has represented clients in major airline disasters to general aviation accidents. ALG has offices in Seattle, Washington, Honolulu, Hawaii, and Jupiter, Florida. ALG attorneys are licensed in Washington State, Hawaii, Alaska, California, and Florida, but can represent clients in all 50 states and have represented clients internationally with the association of local counsel.
Full Text of the NTSB Preliminary Report Follows: