Aero-Tips!

A good pilot is always learning -- how many times have you heard this old standard throughout your flying career? There is no truer statement in all of flying (well, with the possible exception of "there are no old, bold pilots.") It's part of what makes aviation so exciting for all of us... just when you think you've seen it all, along comes a scenario you've never imagined.

Aero-News has called upon the expertise of Thomas P. Turner, master CFI and all-around-good-guy, to bring our readers -- and us -- daily tips to improve our skills as aviators, and as representatives of the flying community. Some of them, you may have heard before... but for each of us, there will also be something we might never have considered before, or something that didn't "stick" the way it should have the first time we memorized it for the practical test.

It is our unabashed goal that "Aero-Tips" will help our readers become better, safer pilots -- as well as introducing our ground-bound readers to the concepts and principles that keep those strange aluminum-and-composite contraptions in the air... and allow them to soar magnificently through it.

Look for our daily Aero-Tips segments, coming each day to you through the Aero-News Network. Suggestions for future Aero-Tips are always welcome, as are additions or discussion of each day's tips. Remember... when it comes to being good pilots, we're all in this together.

Aero-Tips 02.16.06

For several days we’ve been demystifying operation of an airplane’s electrical system by comparing it to the flow of water. Check the last three days' Aero-Tips if you need to catch up. To stretch the analogy even further, let's talk about electrical system indicators.

Please note: This visualization is not technically correct—but it does a superb job of helping pilots comprehend what's going on with the electrical system to accurately monitor it and troubleshoot problems. Engineers, mechanics and purists, please forgive this teaching tool.

There are three common electrical indicators in light aircraft:

1) Ammeter. Amperage is the rate of electrical flow. Equate this to gallons per hour in the water-flow visualization. An ammeter doesn't directly indicate the rate of electrical flow. Instead, it tells us if the battery is:

• fully charged, by indicating a neutral position. Think of it as a pointer attached to the "float" in the "water tank." If the float is steady at the full line, then the pump (alternator) is matching the rate of flow. The needle is centered. Life is good.
• discharging, with a "minus" or "discharge" indication. The float is dropping, and the pointer moves with it, because the pump isn't keeping up with flow—the tank's running dry.
• charging, showing a "plus" or "charge" when the float rises. The tank's overfilling -- meaning the battery may overheat.

2) Buss voltage gauge Voltage is analogous to "water pressure." Buss voltage is the "pressure" available at the distribution point. Normally a "full" battery alone has either 12 volts or 24 volts. When the alternator "pump" is "pressurizing" the system, this goes to 14 volts or 28 volts, respectively.

3) Alternator loadmeter. This measure the output of the alternator, usually in volts (where it should read 14 or 28, as appropriate), or in percentage of the alternator's maximum output (e.g., 25%).

Airplanes may have one of more of these indicators.

Aero-tip of the day: It may be helpful to visualize electricity as the flow of water to better understand its function. Tomorrow: Time for a quiz!

FMI: Aero-Tips