Rarely do we light airplane pilots get to outfly the airlines, but it does occasionally happen.
A dozen years ago, the Flying Carpet suffered a spate of in-flight voltage regulator failures. This device meters electricity generated by the alternator to meet the airplane’s ongoing electrical needs and keep the battery charged. It also protects the electrical system against spikes or shorts that could damage electrical components.
Every few months our latest voltage regulator would fail in flight, disabling the aircraft’s charging system and sending us scrambling for a mechanic. Sometimes it could be temporarily reset by cycling the alternator switch, but usually not. Of course these failures always occurred at inopportune times, and caused lots of “what-if” stress every time we launched on a cross-country flight. Yet the intermittency stymied our mechanics in identifying the cause.
Then one day, a savvy avionics tech at Falcon Field (KFFZ) asked if I could hear our original-equipment flashing beacon cycling on and off through my headset. When I answered yes, he asked if those beacon pulses also presented via the ammeter needle. They did. It turns out that with age, the power supply units for old flashing beacons can internally deteriorate, drawing increasing electrical current as the circuitry fails.
Testing revealed that our beacon was drawing so much current with each flash, that over time it was causing each successive voltage regulator to disconnect the charging system and fail. Installing a new low-power LED beacon finally solved the problem, though it would take months of trouble-free operation before we could fully believe it.
Jean and I launched homeward from Falcon Field that day flashing our bright-and-shiny new beacon, arriving to rare IFR weather in Flagstaff…
**Read Greg’s entire column, “OH, THE GLORY” **.
(This column first appeared in AOPA Flight Training magazine.)
©2019 Gregory N. Brown