On several occasions I have down loaded the charts in the AIP. When planning the trip they are in the memory. After shutting down the iPad and restarting for the trip the AIP charts have disappeared. Have I some incorrect settings?

The thing is, we don't know why your device is losing the file or failing to load it. We have no reason to believe that SkyDemon would be able to load from a backup if for some reason it cannot load from the main file. Indeed, there is every reason to believe that the failure to load from one would mean failure to load from the backup. We have already spent considerable time adding debug and tracing code to the index loading routines with the result that this bug occurs significantly less often than it used to. We will continue to give it thought.