In my mind, the most complex and inscrutable system on any airplane is the electrical system. I take that back. The electrical system on the Piper J–3 Cub in which I’m a partner is pretty doggone simple because it’s confined to generating the spark that fires the plugs that power the pistons that turn the crankshaft that spins the propeller that provides the thrust that makes the airplane go, albeit slowly. Pretty simple, and a stark contrast to an airplane with an electrical system comprised of one or more batteries, one or more alternators (or generators if it’s old school), voltage regulators, distribution buses, circuit breakers, annunciators and, finally, the landing gear, flap, and trim actuating motors, lights, heating elements, and avionics that are fueled by electricity.
Electrical problems usually announce themselves in one of two ways. Either there is some sort of annunciator or gauge indication if the airplane is so equipped, or a circuit breaker (C/B) or C/B switch will pop or trip. Any of these may be evidence that the alternator or battery has malfunctioned, there is a short circuit somewhere in the electrical system, or some problem has befallen one or more electrical components. If you miss those warning signs, there are other methods of discerning that you have an electrical problem. Something may cease to function entirely, and that something could be the entire electrical system. Or, the worst possible indication, an electrical fire erupts.
The worst that can go wrong did when the pilot of a piston twin who was preparing for a flight apparently reset a popped C/B for the airborne weather radar system. Ten minutes after taking off he reported a problem, and two minutes after that the airplane crashed. Investigators determined that an electrical short in the radar’s wiring resulted in an in-flight fire that ultimately brought the airplane down.
By resetting the C/B, the pilot was simply following what has been accepted practice in aviation. That practice says you get one opportunity to reset a popped or tripped C/B. If it stays in and everything works, you’re good to go. If the C/B pops or trips again, do not reset it, because whatever caused it to fail the first time is still a problem.
Unfortunately, the pilot of the accident airplane was unaware that the previous day, another pilot who was flying the same airplane had the radar fail and had also detected a burning smell. He pulled the C/B for the weather radar, returned to home base, and reported the problem. The accident pilot was never informed.
The accident prompted the FAA to issue a Special Airworthiness Information Bulletin (SAIB CE-10-11R1) with some sound recommendations for all pilots on how to respond to an electrical problem with a popped or tripped C/B indication.
The SAIB recommends that C/Bs associated with electrical functions and components deemed essential for safety of flight be located and marked for easy identification in flight. Those and only those C/Bs may be reset after popping, but only once and only after waiting at least one minute to allow wiring or components to cool down, and any smoke or burning smell to dissipate. Nonessential C/Bs should not be reset in flight.
The recommendations beg the question, what is essential for safety of flight? That depends. If you are flying VFR, there may not be any electrical system, function, or component that is absolutely necessary to land safely. You don’t have to have a communications or navigation radio or transponder to make a perfectly safe descent, approach, and landing, especially if it’s at a nontowered airport. You don’t absolutely have to use flaps, and an electrically actuated landing gear has an emergency backup extension system.
It’s a different story when flying IFR in the clouds. Electrical malfunctions and popped C/Bs can be a much more serious matter if you are in weather. But, you may be surprised at how little you really need in the way of electrical equipment to get home safely, even in weather.
Some of the things that can be of tremendous help in the event of electrical problems include a battery-powered portable GPS, a handheld communications radio, and knowing where the heck you are when the screen on your panel-mounted GPS navigator goes blank. And for IFR pilots, know where VFR conditions are before you take off, and make sure you have enough fuel to make it there.
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