Control Surface Failures

This is more of a broad subject than can be covered in this type of article, so make note of your questions and discuss them with your CFI.

Although control surface failures are rare we feel the need to explore at least a few suggestions in case the unlikely may happen. Our only defense against a crimp slipping, a cable becoming slack and coming off a pulley, or a foreign object sliding around jamming a push rod is preparedness, recognition and prompt action.

One of the most important things to remember is to make corrective actions smoothly and with no sudden lurches. Let’s say you are in a standard rate coordinated turn to the right and you suddenly discover your ailerons are jammed, smoothly apply top rudder pressure, skyward rudder or in this case left rudder until directional control is regained. In other words a “slip.” If the rudder happens to be the problem do the reverse with the ailerons to enter a forward slip. You may need to add power to
avoid a cross controlled stall and be aware of your altitude. Upon regaining control announce your problem and your intentions to controllers or to local CTAF. Make all turns toward the low wing. Land on a crosswind runway against the slip, preferably one longer than 4000 ft. Flying in a slight crab position will help to prevent running out of rudder control. This is not pretty or easy but beats making the Metro section of the local paper. Read and talk about slips with your CFI and read your POH in
reference to the same.

Next lets look at the elevator, the primary action that controls pitch. Upon discovering that it is inoperable most airplanes will react to power changes, add power to pitch up and decrease to pitch down. Another method is the trim tab, the elevator within an elevator. The most effective action is a combination of the two. Remember to make small input and power changes, just a few degrees at a time. Do not use flaps during landing, pitch is very sensitive to flap position. There are only two types of elevator failure, cables coming loose or becoming jammed. Depending on which type of failure occurs will depend on which way the trim tab is applied to go up or down. In other words if its jammed roll forward to pitch down and if its loose roll back to pitch down. Another reason for small input changes, just to make sure you get it right for the direction you want to go.

So read, practice and prepare for the unexpected and you will be surprised at the amount of related knowledge that applies to everyday flying. Other items to become familiar with: certification requirements for control failure. How does the trim tab work in a Cessna compared to a Piper? What is the difference between a trim tab, a servo tab and an anti servo tab?

References: Flight Training June 2002

These safety tips are provided by the WCFC Safety Committee. They are intended to stimulate thought and discussion about flight safety and do not necessarily represent club policy nor are they intended to replace instruction from a qualified instructor.