Your card failure may not have been power related, however, my card failure in my 526HP was 100% power failure related. Not just the fact the power went off, it was Off, On, Off, On, Off, On, Off, On, Off, On, On, On, On, On, Off, On and so forth.It's a not a power issue. Not once has power been a factor leading to my failures. Hell, a few drops that did result in cutting out the power suddenly haven't caused any problems.
And it's not an issue of excessive overwrite. All of my failures are cards I was creating to use as backups. Some had been used for other devices previously. But at least one was right out of the package.
A storm came trough the area and CONTRARY to what everyone wants to say, this had noting to do with lightening and I am not always home to turn things off and disconnect them.
The problem where I live is TREES and overhead power lines. Tree branches touch and break off and short out the power lines. This causes power dips and BLIPS while the branches arch and burn up and/or fall to the ground. If and only if the branches cause a short does either a localized circuit breaker open and/or the Automatic Circuit Interrupters open at the Substation, dropping power completely, then after 2-10 seconds the Automatic Circuit Interrupters close back up and power the grid up. This is done in an attempt to re-energize the local grid and if there are still any line faults the rapid inrush current should then trip any localized line circuit breakers and allow the rest of the grid to stay on utility power.
I also have a back up generator for the whole house, other UPS units, just did not and still do not have a UPS unit on my 536HP yet. One will be added in the next few weeks.
So for others, they may not have had power disruptions, and cards were still getting corrupted.
I gave up trying to recover the corrupted SD card after about spending 2 hours on a $5 SD card!