Can flight controls or surfaces on small aircrafts get stuck/jammed hard deflected (due to a flight control failure) if the pilot haven't intentionally deflect them for a maneuver and when they stuck there in position?
It can happen in a number of ways, for instance Poor design, The Bennet PL 12 Airtruck had a problem with the design of its ailerons which caused an aerodynamic phenomenon known as aileron snatch, in which in certain circumstances the ailerons would go hard over. They lost two prototypes before they worked it out. Foreign object obstruction. An Australian CAC-22 (The Australian built P51 Mustang) performed a slow roll. Whilst inverted a 20 cent piece fell out of the pilots pocket and, as the aircraft came upright, fell into the area immediately behind the control column, where the boot at the base of the stick was torn. This prevented the stick from being moved aft, and the aircraft dived into the ground. Control failure. A Boeing 747-400 of Northwest Airlines had the end blow out of the hydraulic actuator on the lower rudder, which allowed the actuator rod to go over centre and jammed the lower rudder hard to the left. Fortunately, being a 747 with a split rudder, the pilots were able to use the upper rudder to retain control to an emergency landing.
It hasn't ever happened to me! One concern with flight controls is that they could be hooked up wrong or adjusted wrong after maintenance, but I don't think that ever actually happens much. Regardless, before leaving the runway, a pilot is always to do a pre-flight check and make sure the control surfaces move smoothly and in all the right directions. Annual inspections or 100 hour inspections on aircraft are specifically intended to catch something like a fraying control cable or leaking hydraulics, so it is quite rare that something like that ever reaches the point of failing in flight. So what would happen if the controls somehow did become disconnected from the yoke? In the case of elevator controls, you would simply use the trim wheel to set the position of the elevator. Ailerons would be expected to only fail on one side, or to both fail equally. In that case most airplanes would stay in flight because planes tend to want to fly upright on their own, to some degree. The rudder can be used to control direction and keep the plane upright to a large degree, with some work. Any time you ask a question starting with Can xxxxxx happen, the answer has to be anything is possible. Did you have a specific accident you are wondering about, or a specific concern?
The incident that Fly Inverted mentioned was Air Alaska flight 261. The Jackscrew that controls the horizontal stabilizer in the tail failed. The Nut was stripped out and the entire jackscrew assembly separated from the nut. The stabilizer deflected well beyond the full nose down position, plunging the aircraft (an MD-83, not a B727) into a fatal unrecoverable dive. The plane rolled inverted and the pilots did attempt to get the nose up by pushing the nose down while inverted but to no avail. youtu.be/srFZ7Jy3YIE Actual ATC voice recording: youtu.be/wTa8GcWnqmk There was a series of fatal crashes on the B737, the most popular airliner flying. These crashes were due to a hard rudder over that for a long time defeated Crash investigators to discover because the failure mode was almost impossible to duplicate and left no evidence in the crash debris. United Airlines Flight 585 and USAir Flight 427, experienced a hard rudder over fully deflected and crashed while on approach for landing. Years went by and Investigators had no clue. Then Eastwind Airlines Flight 517 experienced the same thing twice, both times the pilot barely maintained control by rolling the plane opposite the rudder and holding the plane in a steep bank. The fault was discovered to be a failure of the PCU Power Controller Unit, A Hydraulic device that controls the movement of the rudder. When cold soaked in extremely cold temperatures like on high altitude flights, and then injected with hot Hydraulic fluid, the unit can fail in a full deflection. youtu.be/fO2EitxHOHY
Interesting question. A broken cable in a small plane might cause some consternation, but the control surface should remain in neutral, just from the airflow. Chances are, only one side of the control would fail. The stick or rudder pedals would only lose function on one side. Elevator cables might be more upsetting than rudder or aileron failure. If the balance point is shifted rearwards elevator failure might be more critical than if shifted forwards. Don't forget, elevator controls airspeed. Throttle controls rate of climb. Most non-pilots think of the throttle more as a gas pedal. BTW, this HAS happened. I would be more concerned about a hard over incident in a larger airframe with hydraulic or electrically driven control surfaces. One incident comes to mind. There was an incident off the coast of Los Angeles, where the servo motor for the elevator drove the elevator surface to full up. I recall hearing another pilot with a visual on the incident reporting to the tower that they are inverted now. The airframe was uncontrollable, and they did not recover. The aircraft, if I remember, was a B727, but I could be wrong about that. It was a long time ago.
Unless there is a control system malfunction. no. It is an extremely rare occurrence for something like that to happen. Even a control cable breakage will usually not lead to a jammed control. Not only that, it is very rare to use full control deflections in flight, so a hard over situation is even less likely. The most common flight control problems are the result of improper maintenance.
