There’s little else quite as ingrained in the minds of pilots, or emblematic of flight itself, as the stick and rudder — so what happens when they fail? It would seem axiomatic that losing the ability to turn or bank would set you up for a quick toboggan ride downhill, followed by some very loud and unpleasant noises. Not necessarily…
WHAT YOU CAN’T SEE: The actuating mechanisms that relay control inputs to our airplanes’ extremities are often completely hidden from sight. But we know they’ve been well designed and we’re satisfied with checking just the hinge pins, counterweights, and other exposed moving parts when we preflight control surfaces. Short of making every preflight into a 100-hour inspection, that will have to do. Unfortunately, it’s not all hermetically sealed clockwork in there! Stuff happens! Eventually, something can fray, snag, disengage, or otherwise compromise our presupposed evolution beyond weight-shifting, blowing real hard … or prayer.
Trap: An uncommanded roll can quickly develop into an unusual attitude, and an airplane without an effective rudder has little defense against a spin.
AERONAUTICAL ENGINEERING 101: To enter a right turn, you turn the control wheel clockwise. This moves the ailerons near your wingtips, asymmetrically — the left one goes down; the right goes up. The ‘down’ one increases lift; the ‘up’ one does the opposite; and the airplane rolls to the right about its longitudinal axis. With increased lift comes an increase in induced drag, so as the southpaw side comes up, it also wants to fall behind, and the airplane will yaw to the left about its vertical axis. It’s that extra, induced drag asymmetrically applied to one wingtip that creates the ‘adverse yaw‘ you learned about in ground school. To counteract it, you gently press that right pedal at your feet, which moves the rudder towards the right and causes the nose to move back toward the right in a coordinated turn. (And, as you also recall, that same yaw from the rudder pedals can give you a secondary roll effect due to the advancing wing’s greater forward motion … which also makes that wing generate more lift.)
Aileron Failure: OK then. So we smoothly coordinate our turn … uh oh, wait a minute … something’s stuck. The ailerons are jammed! OK … lessee … they say don’t panic. Just “fly the airplane” … Well, OK, but HOW?
Defense: Control failures are manageable as long as you take action quickly, before an unusual attitude develops. As you recall, ailerons cause a yaw, which you counteract by applying rudder, and what you do with the rudder also induces a roll, which you check with ailerons. Can we say “slip”? We can all say it, but some of you may be unsure just how to start doing one. The slip is a wonderful tool, and a successful slip depends on three magic words: kick top rudder. ‘Top’ being the side that is physically higher — provided you’re not inverted yet. If the ailerons were to jam in our right turn, you would stomp on the left rudder pedal — the one on top — and presto!
AILERONS OR RUDDER: Fly gently. Don’t panic. No sudden lurches, please. If it’s the ailerons that went AWOL, you’ll have an uncommanded roll. Just step skyward (push the top rudder pedal, the one on the high side) to fly into a slip. That’s how you’ll maintain directional control. From this, you can see that if the rudder were the problem, you would simply manipulate the slip with ailerons instead of rudder. The slip involves both controls — use the control that works.
COMPLICATIONS: You’ll need to…
- Add more power, and watch your altitude.
- Stabilize flight by flying a ‘controlled’ forward slip.
- You may want to attempt to dislodge any foreign objects that might be causing the jam by applying a sudden input to the jammed control — be aware that exercising this option may make things worse.
- Make all turns towards the low wing, obviously.
- Get help! Let ATC know what your problem is. Your next concern is getting down. If your home drome isn’t a mile long, go somewhere that is.
- Land on a crosswind runway that makes the slip an advantage.
BOTTOM LINE: Flying cross-eyed ain’t pretty, but it beats making the Metro section. You can’t practice breaking your airplane, but learning about and flying good slips might pay off bigtime.