By Scott McFadden, EAA 611467, Thunder Bay, Ontario
I was having problems with the red beacon atop the fin of my aircraft. The breaker would occasionally pop and despite cleaning all the connections and grounds, and bench testing the power supply (flasher unit), no real cause was identified, and the problem persisted intermittently. I was considering replacing the resistor, which is the only other component beyond the power supply and beacon light/socket, but one day the light just remained on, indicating the problem was the power supply.
Although a very common component, the power supplies are no longer available new and rarely available used/serviceable. So, I thought, “Very common part, there must be an aftermarket replacement.” Well, there kind of is, but the entire beacon must be replaced as the replacement power supply is not compatible with the original beacon mount and bulb.
OK I thought, it’s probably time I took advantage of newer technology, believing that parting with close to $1,000 would achieve that objective. So, I was disappointed to learn that newer technology in this case meant 1980s! Fortunately, I have wing tip strobes, so the beacon is optional. I decided to take a little time and do some more research. I removed the power supply and removed the cover. This involved drilling out four pop rivets and removing two nuts from what looked to me like a couple of large diodes (the cover also acts as a heat sink). Inside I was pleasantly surprised to find … not that much. The most important thing (to me) was that there were no chips (aka integrated circuits, which tend to contain all manner of unexplainable functions).
Now I’m no electronics whiz, but I do know that resistors, capacitors, and small diodes are reliable. Higher failure rates are associated with components that get hot or perform switching function. I recognized the little black tripod on in the centre of the board as a transistor of some kind and luckily was able to read the number written on its face. $10 including shipping and a week later I had two new replacements in my possession. So, it was with great excitement and anticipation that I carefully soldered one in position. Same problem.
Next up, the gizmos requiring the heat sink, clearly something that gets hot. So, I removed both of them and compared with my multimeter, a procedure that informed me of precisely nothing. However, I was able to read a part number after carefully peeling away some of the lacquer. Turns out these things are called “silicon-controlled rectifiers” and I found two online for US $39 plus $5 shipping.
What a great feeling it was to sit by my work bench watching my beacon flashing away just like it’s supposed to! I repainted where I had removed the lacquer and had some heat sink compound “in stock” to make the required thermal connections to the heat sink cover. Following the photos I took during disassembly, the insulating and non-insulating washers were assembled as they were before, and then the case was re-riveted back together. I left it flashing on the bench for the next 6 hours or so, checking for any hot spots.
I’m pleased to report that the beacon continues to function, and my wallet is only $54 US lighter. In the 1980s this sort of repair would have been done routinely, including on certificated aircraft. These days, in our “throw away” society, we tend to not even consider this type of repair option and, particularly in the non-aviation environment, most electronic components cannot even be opened, and even if they can, the circuits tend to be dominated by chips and unidentifiable parts.
I’m in the market for a replacement vehicle, my current steed having reached the end of its structural life. This 27-year-old vehicle (450,000 km, oil change each 100k whether it needs it or not) has some elegant technology. It has a cable that connects the accelerator pedal to the throttle body on the engine! It has another cable that connects the throttle body to the transmission. When I pull out to pass, and put my foot on the gas, there is an instantaneous, predictable, and pleasing response from the vehicle. I’m sure Louis Hamilton’s Mercedes goes when he presses the go pedal, but it would seem there’s not a family vehicle on the market today with the same attribute!
Anyway, in recent times we’ve seen how dependant our society has become on chips. Astonishingly 70% of the world’s supply comes from a single country (whose sovereignty is under intermittent threat).
The automotive sector is totally dependent on chips and the programmers of same. In aviation we’ve seen the catastrophic and tragic results of a fundamental disconnect between chips engineers/programmers and flight crews, leading to two otherwise completely serviceable airliners flying into the ground despite the best and competent efforts of their crews. The term “unsolicited excursion” became part of aviation vernacular shortly after fly-by-wire aircraft appeared in commercial aviation! As demonstrated recently, the major air transportation companies have no plan B, no manual backup capabilities. When their computer systems have problems, airlines, air traffic control organizations, air cargo operators, airports just shut down. Is this any way to run a civilization!?
As aviators we sometimes complain about the lack of technological advancement in GA. Perhaps that cloud has a silver lining after all. There’s more to be said about keep it simple these days as it is clear our lives, economies, food, fuel, heat, etc. are almost totally dependent on chips. Chips we occasionally can’t get, don’t make, don’t know how to make, and are vulnerable to incorrect, inadequate, or even nefarious programming by a relatively small number of very specialized individuals.
What I can say with 100% certainty is that I’m happy with my airplane, and if there was a car on the market that didn’t rely on chips, I’d buy it in a heartbeat!
P.S. As an AME I view the beacon fix as a minor repair to a non-critical system using commercial parts that are numbered and therefore traceable as to source and specifications. I have a leased hangar/shop at YQT but I also have a hangar at KCKC (a topic of future articles perhaps). I have a commercial, IFR, and AME. My ‘46 Taylorcraft was 2019 Oshkosh Grand Champion, and I was CEO of the Thunder Bay Airport Authority for 17 years to 2014.