Many times I hear engineering and management teams complain that DO-254 costs them a lot of time and a lot of money. But when I get to review the work that they have done to comply with DO-254 and the latest guidance from the FAA and/or EASA it really comes down to poor planning and a lack of understanding of why they are applying this design assurance standard in the first place.
Always remember that the reason DO254 is being required is as a means of compliance to the CFRs (or EASA CSs) in order to demonstrate that it “performs its intended function under all foreseeable operating conditions”. The Design Assurance level (DAL) adjusts the amount of rigor required in order to demonstrate this. Keeping the primary goal and understanding of the Certification regulation in mind will keep you spending time and effort on what is important, that it functions as intended in the aircraft.
If your team is seeking to understand the purpose of DO-254, Patmos Engineering Services offers a class called “DO-254 Airborne Electronic Hardware Certification,” which covers the fundamentals of DO-254 compliance, including why you have to do.