Fliegen Works Inc.
Aeronautical Engineers – Portland, OR – USA

How to Use a FAA DER

So the FAA has told you you need  a DER for approvals and to help on your project.   Now what? 

You should consult with your DER early on a project.  We often get data that was prepared by an applicant that does not include all the information required for compliance.   Some applicants provide way more data than required, or data that is not FAA acceptable, such as an unvalidated FEA on a structure.  As consulting engineers, we can assist the client in preparing the right data to demonstrate compliance to the Code of Federal Regulations.   A good question to ask a potential DER is how many different certification projects have they worked on.

If you plan on producing your own data and want DER approval later, ask your DER what needs to be in your reports, drawings, and calculations.  A few items that are often missed are the certification basis, the use of average material properties instead of A or B Basis allowables, and acceptable material specifications that match the calculations.  For structures, it is important that the weights are well defined and that the loading assumptions are correct.  Interior components that need to meet crashworthiness also need to meet the flight loads, which sometimes are higher.  If you are unsure, ask your DER.

DERs are required to have at least 8 years of engineering experience and a thorough knowledge of the regulations and guidance material in their field.  Most of us have been through multiple certification projects with the FAA.  This experience is useful to the applicant since we have a good understanding of what the FAA requires, both thoeretically from the FAA regulations or policy material, and practically from past certification project experience.   The guidance material, such as the Advisory Circulars, and the FAA policy, such as Orders, can be quite thick but do not spell out a formulaic method to certify an aircraft or component.


The FAA has had provisions for DERs since the beginning of the FAA in 1962.   Back then the FAA had more engineers per aircraft than they do today.  The FAA engineers used to have time to thoroughly review, (including checking all the formulas & math,) all the data that was submitted.  Now the FAA primarily manages certification programs and spot checks engineering data.  They review the data submitted against the certification plan – which they review thoroughly.  They expect each finding of compliance to be supported by an 8110-3 from a DER.  There are a few items that the FAA still internally reviews and approves, although they also expect that data to have been formally or informally reviewed by a DER. 

There has been a recent push in the FAA to go to Organizational Delegation.  This allows the FAA to do very little project specific review, instead it can focus on review and auditing of an organization.  Within that organization are Authorized Representatives that have been qualified and vetted by the organization.

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