To my knowledge all upgradeable software is treated exactly like a new part. Upgrade must be certified, and is visible in part databases with part number. Th

To my knowledge all upgradeable software is treated exactly like a new part. Upgrade must be certified, and is visible in part databases with part number. There must be a chain of trust. If it's a field upgradeable part, it's delivered in flash drives. If it's something more fundamental, they take the aviation computer out and update the EEPROM. Certifying a upgrade is the hard part.