MGL Avionics User Forum

Landed at my home airport and was planning on going for a second flight after lunch.

When switching the iEFIS on it failed to boot. It boot 5 blocks and then failed to load EXP3. When trying to boot the system from an external SD card I got error code 2 and it didn’t boot up either.

Had to remove the iEFIS from the panel, take it home and replace the internal SD card. Assume the internal SD card became corrupted. Lesson learned. Always keep a backup system SD card with you otherwise someone might get stuck at an airport if operating with a single iEFIS.

It happens sometimes - good thing is that it's an SD card so fairly easy to replace.
Systems relying on soldered flash memory chips present a serious issue when things go wrong so while we did that early with the Enigma as the MMC cards at the time where simply too slow - we quickly changed that. The G1 CPU card had a compact flash card (as was popular at the time with cameras) - the G2 changed to SDHC and the G3 to SDHC micro cards.
The G4 continues the tradition.

We found the SD Micro cards the best when it came to retaining information without corruption but it's fair to say this varies and I can't even state that brand names are any better than the cheap ones.
I have two SD cards on my desk we pulled from repairs (with corrupted cards) - both of these show similar patterns - the data and file system mostly intact but there are random bit failures all over the card - interesting is that it is limited to certain bits within a byte and the failures are grouped - but completely independent on file system structure. Basically it means the system itself could not have been doing this.

SD cards fail all the time - but usually you do not notice as they have built in error detection and correction. The memory storage in these cards is quite flawed and has limited ability to write - but reading is not a problem. The card itself is able to correct for bit errors provided they are not too much - usually they can detect and correct two bad bits in a sector of 512 bytes - this also then causes a swap of the bad sector with a spare one - you may have noticed that for example a 16GByte card tends to give you only 14 or so GBytes - that's because a few sectors are faulty right from the start and it keeps a batch of spares for replacement for cater for later failures.
Most cards by far seem to just go on forever and seem good even after many years of use - sometimes you get one that falls over early. Luckily it does not happen often.