Don’t Get Brushed Off

This story is more for owners than renters, but everyone can learn from this. Knowing how your airplane works is important — and that includes the need to know what various components in your airplane do and how they work.

This is an excellent example of a motor that is included in most planes that are flying today. The flap motor has a simple mission: it is usually connected to a gear or hydraulic system, and its job is to make your flaps go up and down at your request. Simple and efficient, most flap motors are designed for years of trouble-free operation.

Note: A “year” is defined in Webster’s as ‘the period of 365 and 1/4 solar days required for one revolution around the sun.’ Your electric motors are designed to operate for a few years, typically 3 to 5, before requiring an overhaul. There are various bases for the amount of time flown in a year, but the bottom line is simple: Flap motors won’t last forever without maintenance.

The maintenance in this case can be simple or complex. If you have your flap motor and other motors serviced on a regular basis, your repairs would include cleaning and stoning of the commutator, which is designed to take electricity from the battery or alternator and transfer it to the rotor. Other maintenance might include replacement of the carbon brushes, which transfer the electricity to the commutator.

Over the course of the years, your brushes will wear out. This is caused by the friction with the commutator, which grinds a little off the brushes at each use. When you have your motors overhauled on a regular basis, the new brushes and cleaned up commutator are sufficient to keep your motor humming along quite nicely.

Aside from the surprise that you get when you flip a switch and nothing happens, running a motor to failure typically causes more damage (read: more expensive repairs and overhauls) to the motor. In extreme cases, the commutator can actually be deeply grooved, making the rotor unserviceable. If this happens, you may be forced to purchase a new or rebuilt motor, which will cost you four to six times more than a regular overhaul.

Then there’s the smoke

If the brushes wear down enough, they may lose good contact with the commutator. If they do, the current at the brushes will increase, which causes the motor to heat up more, which in turn can cause the motor to smoke out. Once you let the smoke out of the motor, it’s pretty much done. Of course, if you smell or see the smoke, your calm and pleasant flight is pretty much done, too. In the end, your shop will be forced to find you a rebuilt or new motor to replace the motor that smoked. You will be left with an expensive repair bill and some dirty underwear. On the bright side: your old motor will now find good use as a nice, smelly doorstop.

If it is a landing gear motor, you will be able to crank down or pump down the landing gear. However, if your flap motor goes bad, you are pretty much stuck with the flaps you had when the motor went south. This could range from no flaps, which means a no-flap landing, to full flaps, which may mean an awkward go-around. Are you up to the challenge that a bad motor can throw at you?

How many years or hours do your motors have on them? If you don’t know the answer to this question, it is past time for you to dig out your logbooks and find the answer. Once you do, discuss the age of your motor with your mechanic, and find out what the recommended frequency of overhauls or rebuilds is for the motors on your airplane.

Important: if your plane is used for flight training, the motors will generally see more wear, and will require more frequent maintenance.

BOTTOM LINE: With a little proactive maintenance, and keeping track of the hours of operation of our aircraft, we can properly maintain our airplanes’ electric motors and in doing so, avoid any unexpected challenges. By taking good care of the motors in our aircraft, we can also avoid the expense of a motor failure… as well as the inconvenience of having a motor failure stink up our cockpit and fill it with acrid smoke.