AC 20-152

The Advisory Circular AC 20-152A, Development Assurance for Airborne Electronic Hardware, identifies the RTCA-published standard DO-254 as defining "an acceptable means, but not the only means" to secure FAA approval of complex custom micro-coded components within aircraft systems with Item Design Assurance Levels (IDAL) of A, B, or C. Specifically excluding COTS microcontrollers, complex custom micro-coded components include field programmable gate arrays (FPGA), programmable logic devices (PLD), and application-specific integrated circuits (ASIC), particularly in cases where correctness and safety can not be verified with testing alone, necessitating methodical design assurance.

For DAL D hardware, as long as the applicant follows DO-254, the applicant does not need to apply this advisory circular since the FAA does not expect to examine the life cycle data. However, if the applicant chooses to follow other design practices for DAL D hardware (as permitted by this AC) the FAA will review the data.