He performed the break-in procedure, but when he shut down, he discovered that the tread on the new left tire had ground down in one spot all the way to the tire cord. He hadn't heard any telltale tire squealing while performing the break-in procedure, but there was no question that the tire was toasted and had to be replaced.
What happened? Apparently, the combination of new brake rotor and new brake pads gave the left wheel more braking power than the right wheel. When he applied the brakes while taxing, the left wheel locked up and the tire slid on the pavement, grinding off a big patch of tread in a matter of seconds.
My partner was embarrassed by the incident, but he shouldn't have been. I would have suffered the same fate.
Braking is given scant attention in training, but there are nuances that can have important consequences, as my partner and I found out. The braking system on a typical light, fixed-gear single is simple and the procedures straightforward. Even so, braking is a skill to be mastered, especially if you plan to move up the aircraft complexity ladder.
Brake systems differ in design, operation, and effectiveness. Some older tailwheel aircraft, including the Piper J-3 Cub, employ simple cable-operated brakes - no hydraulics, no master cylinder - that you activate by pushing on pedals with the heels of your feet. In many tailwheel aircraft the pilot must steer using differential brake pressure while taxiing because at slow speeds the rudder is not effective. Using brakes to slow or stop a tailwheel aircraft calls for extra finesse. Too much brake pressure could cause the airplane to nose over.
The first airplane I logged instructional time in was a Piper Colt, a 1950s-era tricycle-gear adaptation of the Piper Pacer taildragger. One of the Colt's unusual features is the long metal brake-lever handle protruding from beneath the center of the instrument panel. Pull on the lever to activate both main-wheel brakes. Braking doesn't get much simpler, but it comes with a price: no differential braking capability.
Most light tricycle-gear aircraft have brake pedals incorporated into the rudder pedals, which means the pedals perform three separate functions: rudder control, nosewheel steering, and main-wheel brake control. One exception is the AA-1 and AA-5 series of Grumman fixed-gear singles, all of which have a castoring nosewheel. With no nosewheel steering function, the pilot must use differential braking to taxi-steer, just like on a tailwheel. Just as tailwheel flying experience can enhance the skill level of a tricycle-gear pilot, learning to "drive" a Grumman single can help a pilot develop a finer sense of feel for aircraft braking techniques.
In any airplane it's always a good idea to tap the brake pedals just after starting to taxi to see if the brakes are working, and to grind off the patina of rust that forms on the brake rotors after every use. The rust is harmless unless it's allowed to remain and corrode the surface of the rotors.
The basic technique for braking is to apply even pressure equally to each brake pedal for slowing in a straight line and stopping. Or, to make a sharper turn than is possible using nosewheel steering, you can apply pressure to either the right or left brake pedal to decrease the airplane's turning radius. Unless I'm in an airplane with a castoring nosewheel, I try not to use brakes for normal turns. Instead, when approaching a turn I reduce throttle to reduce taxi speed, then make the turn using nosewheel steering only.
Airplane parking brakes are notoriously flimsy and usually are only marginally effective. I never use the parking brake, preferring instead to mash the brake pedals while performing the pretakeoff checks. I glance up from the checklist often to ensure I'm not inadvertently relaxing my toe pressure and allowing the airplane to creep forward.
The most important precaution I observe when using brakes is to make certain that before starting the takeoff roll or touching down on landing, the balls of my feet are resting on the bottom of the rudder pedals and not the top. Otherwise, I'll be applying brake pressure on takeoff or landing. The airplane may not achieve takeoff speed or a wheel could lock up on landing, causing a tire to burst.
After liftoff, it's a good idea to tap the brake pedals to stop the wheels from turning. This stops any vibration from a spinning wheel. It's also good preparation for transitioning to retractable-gear aircraft, where part of the gear-retraction procedure may include tapping the brakes before selecting gear up.
On final approach, confirm that your feet are off the brake pedals, then make a full-stall touchdown to minimize braking on the landing roll. Hard application of brakes is uncomfortable for everyone, and unnecessary except in unusual circumstances. If there is reason to be aggressive with the brakes when landing on a short runway, apply brake pressure firmly and smoothly to avoid locking a wheel and skidding. In most aircraft, raising the flaps after touching down helps transfer weight to the wheels for more braking power on a short-field landing. But be sure it's the flap lever and not the gear lever that you retract.
It's important to develop a fine touch on the brakes so that good technique becomes habitual. The best advice I ever received was to push on the tops of the brake pedals by squeezing my toes. Instead of mashing the pedals with the full force of my legs, the pressure comes from my toes, giving me a more sensitive feel for braking pressure. Try it.
Along with squeezing with your toes, strive to use the brakes only to stop or to pivot in tight spaces. Next time you fly, try taxiing to and from the runway without using brakes except to come to a halt when needed. You'll probably discover that you rarely need brakes to slow, even on the landing roll and when exiting the runway.
Considering the total time an aircraft is under way, brakes are little used. Even then, we probably use them more than necessary. It's possible to get away with sloppy braking in a light airplane, but do we want to settle for sloppy?
