By Bjorn Fehrm

August 15, 2025, ©. Leeham News: We do a series about recent ideas on how the long development times for large airliners can be shortened. New project talks about cutting development time and reaching certification and production faster than previous projects.

The series will discuss the typical development cycles for an FAA Part 25 aircraft, called a transport category aircraft, and what different ideas there are to reduce the development times.

We will use the Gantt plan in Figure 1 as a base for our discussions. Before we start the discussions, we outline the process to certify a transport category aircraft under the US FAA 14 CFR Part 25 regulations and how it relates to the Figure 1 plan.

Figure 1. A generic new Part 25 airliner development plan. Source: Leeham Co. Click to see better.

The certification process

The FAA certification process is described in 14 CFR Part 21. The responsibilities and procedures the FAA must follow to certify new civil aircraft as required by 14 CFR part 21 are described in the FAA Order 8110.4C.

We will use a chart from this document to couple the certification process to our generic program time plan in Figure 1. We then detail the discussion of the different program phases in subsequent Corners, examining what the long pole is in the work, what can be sped up, what is tricky, and how certification influences the work.

To help me with knowledge around all this, my mentor colleague at Sustainable Aero Lab and experienced Part 23 and 25 program manager, Henry Tam, will join us from part 4 (we last worked together on the certification series around Part 23 aircraft that you find here).

The FAA certification of an aircraft

The FAA Order 8110.4C has the following graph of a generic FAA certification process (Figure 2). This graph is a flow chart with a lot of events and actions, along with many abbreviations.

We will focus on a few today and then revisit this chart and its contents as we progress through the aircraft program’s phases in Figure 1, step by step, and describe what actions are required from the certification side for the phase.

Figure 2. A generic FAA aircraft certification process as described in Order 8110.4C. Source: FAA. Click to see better.

As a new aircraft project is getting more and more likely in the Feasibility phase, the Project makes the first contacts with the FAA to do Process Orientation. From 8110.4C:

During this initial contact, a certification branch project manager should discuss the type of requested approval with the applicant and assess the applicant’s knowledge of certification procedures. The project manager needs to conduct a process orientation for applicants who are unfamiliar with certification. The process orientation establishes a partnership with the applicant and provides an opportunity to develop an understanding of the type certification process as it applies to the applicant’s design. The orientation should explain the need for certification, the certification process, the FAA’s role, and the applicant’s responsibilities.

The FAA, unlike some other regulators, helps the Type Certification Applicant with advice, dependent on the competence and previous experience of the applicant. After the Process Orientation, this is continued in Pre-Project Guidance. The FAA certification branch will now direct the potential applicant to appropriate regulatory, policy, and guidance material, among other information.

When the aircraft in the Feasibility phase or Conceptual design has settled down to a defined aircraft variant or variants, Familiarization Briefings are done to give the FAA a good understanding of what product is to be certified and later brought to market. This is an iterative process, and the FAA encourages early briefings, even if things are still a bit fluid.

Once it’s time for a formal Type Certificate (TC) application, we are probably into Conceptual Design. An aircraft TC application must be accompanied by a three-view drawing of the aircraft and available basic data.

A Certification team shall be set up by the OEM, and the FAA shall set up a Type Certification Board (TCB), which is the FAA management team. The first TCBM, Type Certification Board Meetings, are done.

Now the certification work starts in earnest. The OEM must submit a Certification Plan (CP). This is submitted in its first version and then continuously updated as the project progresses. It can be incomplete initially, but must finally contain:

(1) General information, including applicant identification, application date, model designation, and so forth.

(2) A description of the proposed design or design change, including sketches and schematics.

(3) The intended regulatory operating environment (for example, 14 CFR parts 25, 33,.., 121, …).

(4) The proposed certification basis, including applicable regulation paragraphs and subparagraphs with amendment levels, exemptions, ELOS (Equivalent Levels of Safety) findings, and special conditions.

(5) A description of how compliance will be shown (ground test, flight test, analysis, similarity, or other acceptable means of compliance).

(6) A list of documentation that will be submitted to show compliance with the applicable certification basis, and how the applicant will ensure that all showings have been made.

(7) A list of test articles to be used to generate compliance data.

(8) A description of how the continued operational safety requirements will be met after the TC is issued.

(9) A project schedule including major milestones, such as preliminary hazard analysis submittal dates, substantiating data submittal dates, conformity and testing completion dates, and expected date of final certification.

(10) Identification of all DERs intended for use in the certification project, their areas of authority, and whether they will be approving data or recommending approval of data.

(11) Identification of all FAA delegation activity intended for use, their authorized function codes, and their proposed inspection activities.

As can be seen, the certification work now requires an organization within the OEM to generate all necessary information and documents, and to track and manage the project from a certification perspective.

We then enter the Compliance Planning phase, where the Certification Basis is established by the FAA and the OEM, based on the requirements of 14 CFR regulations that apply to the project.  Plans for how to show Compliance with these regulations are developed. The project is now in the Preliminary Design Phase and going into Detailed Design.

The FAA is now judging when a particular decision or event is critical to the safety of the product or to the determination of compliance. The FAA will be directly involved in checking that the rules are followed and that compliance is correctly shown. For less critical areas, the FAA will delegate its oversight to specially assigned OEM personnel, contracted or not, so-called DER (Designated Engineering Representative) or DAR (Designated Airworthiness Representative). We come to how these work later in the series.

Then we come to the Implementation phase, which is where the Detailed Design has resulted in design, production, and test of System and Flight Test articles. The certification activities are now focusing on Compliance Data Generation, Compliance Substantiation, and Compliance Finding, i.e., it’s about simulations and tests where the results shall show that the product will comply with the applicable requirements.

If all requirements compliance is documented and agreed upon, the FAA will issue a Type certificate, and we pass into the Post Cert Phase, where the Instructions for Continued Airworthiness (ICA) must be followed for the aircraft to continue to be airworthy.

We have more certification activities around the Design and Production Organization, but we will take these discussions later in the series.