I was recently reminded of the vulnerabilities of our hardware. After a flight my passenger apparently twisted the mic jack when removing his headset such that it shorted out on something to totally foul up the system. On the next flight both transceivers were in transmit mode only i.e. hot mic. The avionics tech troubleshot the problem in 10 minutes, repositioned the jack and we were on our way. His parting comment, ” We see this a lot.”
That got me to thinking about other single point system failures beyond the engine itself. In IMC and at night the hardware becomes increasingly important. Dual radios incapacitated by a single jack, a transmit relay, or a sticky mic button are all examples just within the comm system. This is not a benign failure either. Not only does it booger up your aircraft (that’s a technical safety term) – a single stuck mic can mess up an entire ATC sector frequency.
As we go about improving the hardware, seems like a simple insulator around jacks would be an effective and cheap solution. Perhaps there are some avionics types reading who could shed some light on this. I wonder what other single point system failures are lurking. Long ago, I gave up on a single power source for primary flight instruments in IMC. A single dry vacuum pump to power some of the most critical equipment is not a recipe for success.
What single point failures have you had? Did you add redundancy or change your flight operation to avoid the problem in the future?