By Bjorn Fehrm and Henry Tam
September 26, 2025, ©. Leeham News: We do a series about 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.
Figure 1. A generic new Part 25 airliner development plan. Source: Leeham Co. Click to see better.
*** Special thanks to Andrew Telesca for helping with this article***
Certification Work during Conceptual Design
If we want to execute our program quickly and efficiently, we need to come out of the conceptual design phase with a clear roadmap for how we will integrate compliance into our design efforts. Aerospace is a strictly regulated industry, especially for transport category vehicles, and this means there are compliance considerations in almost all of our engineering and program activities. A quality roadmap at this phase will prevent significant pain and delay once we reach the implementation phase.
In this article, we’ll look at four key topics:
- Interaction of regulatory policy and early design decisions
- Integration of compliance into program infrastructure
- Building a strategy for major certification milestones
- Tactics for reducing the compliance cost and timeline
Interaction of regulatory policy and early design decisions
The most critical interaction between certification and design at this phase is a simple question: do we know how to certify this technology? To be successful the answer for almost all aspects of the proposed design should be yes. For each function and technology, including manufacturing technologies, this question should be asked when trading it into the design. Want to use advanced materials for the wing? Do we have a path to establishing the required design allowables (strength characteristics) and ensuring sufficient production consistency for those values to be reliable? Want to include new communications protocols as part of an integrated modular avionics suite? Then either in house or through the supply chain there must be clear knowledge of how to show that technology has the integrity required for the criticality of the signals to be processed.
Of course, in order to compete we will also need to innovate, and this means at least a handful of design elements where the answer to this question is no. Each such design represents a major program risk and must be identified and treated as such from the beginning. This means that each of these items must provide enough benefit to the bottom line performance or economics of the product to be worth the risk. For our sample project an example of this would be the hybrid propulsion system. Such a technology has yet to be certified, but if we assume this can provide a 5-15% fuel efficiency improvement, then the risk (well managed) is worthwhile. Once these design elements are identified a specific plan should be established for each one identifying the team who will establish the compliance approach, state of current industry/regulatory dialogue on the technology, whether current regulations are sufficient to cover the technology (gap analysis), what verification activities should be evaluated for showing the technology is safe, and initial dialogue on each technology with our national regulator (FAA, EASA, etc.) should begin in this phase.
Finally, we must confirm if there are new regulations or policies that may invalidate our past understanding of design compliance. Every year, the regulators update the airworthiness requirements to account for new learning. This can be due to past accidents or incidents, new technologies, or dialogue between industry and regulatory agencies. A good example of this was the Electrical Wiring Interconnect System (EWIS) regulations. While wiring has been on aircraft for many decades, it was relatively recently that systematic rules were introduced for assessing those wires together as a system, including bundle-level risks and functional separation requirements. If a program were started assuming old wiring methods would be allowed without accounting for the new rule, years of delay would be seen late in the program to change equipment locations, redesign and reroute wires, with knock-on effects to structures and other interfacing designs. Each new regulation should be assessed in this phase and, if significant, treated like the new technologies described above.
Integration of compliance into program infrastructure
In addition to the design aspects, it’s important to realize there are compliance considerations for other aspects of the program as well, and there must be a plan to embed these into the infrastructure of the program. This is more than just having a certification group—it requires that compliance threads through every core engineering and manufacturing function.
- Requirements management: For complex systems development, there are strict rules for the management of requirements, including their integration with the safety processes (such as hazard assessments discussed in the previous article). This means that the processes & tools used for requirements development, validation, and verification need to be designed for compliance from the beginning; otherwise, there will be significant rework later in the program.
- Configuration management: One of the biggest areas startups struggle with is establishing the processes and tools for configuration control early. No certification work can occur if the design baselines’ compliance is not clear. This means control of not only design, but also certification-relevant data sets such as requirements baselines, analysis models & validation data, as-built configurations, and document controls. A well-architected tool set is essential for faster product realization, and it becomes increasingly challenging to introduce as the program progresses and the amount of data increases. This is also a good time to plan for negotiating any configuration processes that require regulatory concurrence to streamline compliance demonstrations.
- Supplier contracts and quality clauses: At this point in the program, supplier selections are a significant consideration, as previously discussed. If the right requirements are not flowed down when a supplier is brought on contract, significant cost assertions or delays could result later in the program. Supplier control is a key area of regulatory oversight for an OEM.
- Data retention and traceability are critical, as regulators often request historical data years after an approval. Digital infrastructure for data storage, retrieval, and security should be designed early to avoid costly retrofits. Loss of development data can not only have direct costs if it needs to be recreated, but it can also put a company afoul of regulatory requirements to retain certain information.
In short, compliance should be designed into the program’s operating system, not bolted on at the end. However… too many controls too early will slow us down. More on that below.
Building a strategy for major certification milestones
This phase is also when certification milestones should be integrated into the program schedule, and strategic decisions about the certification approach should be made. This is best done through alignment of compliance activities to engineering gates. Some important items to consider include:
- Compliance requirements: How will we reach agreement on the compliance approaches for the risk areas discussed above by the time we’re committing the resources to develop detailed designs (PDR, i.e., Preliminary Design Review) and start production (at CDR, Critical Design Review)? How will we know? This will be the topic of a future article.
- Certification planning: Have we outlined a top-level certification plan for the project, including where the organizational boundaries will be between different compliance activities? Which activities do we want suppliers to be responsible for, for example, through TSO acquisition (FAA Technical Standards Order) or detailed software development (DO-178C) compliance? How will we sequence the development of certification and testing plans to ensure incremental maturity development that is on pace with the overall program to avoid late surprises? This will also be the topic of a future article.
- Test assets: Do we have a plan for when we will have identified critical test assets that will be needed to achieve certification? Some test rigs can take years (and tens of millions of dollars) to build. If we’re going to use certain unique test facilities, they can also book years in advance. It’s too early to know everything we will need, but a plan should be in place to ensure critical decisions are made with enough lead time to execute and avoid delays.
- Long-lead parts: How will long-lead parts and early compliance data gathering be handled? While we won’t start most of our formal compliance demonstrations until after CDR, we may need certification data for certain parts (such as design allowables for novel materials) as early as PDR. What is our plan to engage the regulator to allow early data collection in critical areas with certification-level controls?
- Type Inspection Authorization (TIA): When in the program will we switch from company data gathering to formal compliance flight test data? How mature will the aircraft be at the time, and therefore what agreements need to be in place with the regulators?
- Production Certification: Production of aircraft is just as regulated as the design. What’s our Quality Management System development plan? When will we engage with the regulators to start production audits? What gates should we pass before spending the time and money conducting First Article inspections and reviews or conducting on-site supplier audits?
- Foreign validation: Do we plan to certify with a single regulatory agency in our home country (such as we see with Chinese aircraft), or are we targeting an international market? If we’re targeting an international market, what’s our target order of engagement and timing? Are there significant differences in foreign regulations that we need to design for from the beginning, such as stricter cold-weather requirements (Canada) or more stringent data integrity standards (Europe)?
There are many questions that we can answer – or have a plan to answer – at this phase in the program in order to avoid surprises and delays during production & testing, when they will be far more costly.
Tactics for reducing the compliance cost and timeline
Certification is inherently resource-intensive. The people, systems, test assets, and time required to achieve certification are one of the largest barriers to entry in the aerospace market. As a result, an efficient certification effort is one of the largest levers when it comes to hitting program cost and schedule. Several tactics, both new and old, should be considered when seeking faster certification:
- Model-Based Systems Engineering (MBSE): Early adoption of MBSE provides traceability from requirements through architecture to verification. This reduces duplication of effort and provides regulators with a clearer audit trail. A quality digital architecture can only be established from the conceptual design phase, but it will have benefits in every phase to follow.
- Requirements scope (and risk) control: There is always a temptation – both in engineering and marketing – to increase requirements scope. Every new, interesting, or pet technology will have an advocate who wants to add it to a new aircraft development. However, as we discussed above, each of these items carries compliance risk that cannot be overlooked. Sometimes the best way to go faster is to do less.
- Digital vs. traditional data control: Using digital certification data packages instead of paper-based approaches can streamline regulator review, reduce errors, and shorten approval loops. However, early regulator coordination and agreement is needed to ensure such approaches are compliant to regulations that were written with paper-based systems in mind. There is a lot of value in a digital twin – but much less if you still need a set of traditional drawings to accompany it.
- Analysis and simulation opportunities: Modern high-fidelity models can replace or reduce some test campaigns, provided they are validated early and accepted by regulators as part of the compliance plan. This requires a plan that targets high-value test campaigns, identifies the required models and simulations that can replace them, and integrates model validation activities with product development so that the models can be shown to be certification-ready.
- Targeted rapid prototyping and design iteration: Prototyping early in areas with high compliance uncertainty helps de-risk later formal testing. Especially for a startup, sometimes there are lessons that must be learned through trial and error. This is one of the most critical decisions for any program that wants to reach the market as soon as possible – when to apply rigorous controls (requirements, documentation, production, etc.). Applied too early, certification controls will slow down every single engineering and production activity you conduct. Applied too late, work products will be unusable towards final compliance and will end up discarded and repeated. A program that wants to go fast needs a deliberate strategy for design iteration that integrates progressive controls with design/technology maturation. This can be extremely difficult to enact when faced with funding sources that see iterative processes as wasted cost and time.
By deploying these tactics, programs can not only reduce cost but also gain schedule margin and regulatory confidence, both of which are essential in a competitive aerospace environment.
During conceptual design, a program needs to internalize that certification is not a box to be checked at the end of development—it is a design constraint and an opportunity for efficiency from day one. By integrating compliance into early design decisions, embedding it in the program’s infrastructure, aligning around major certification milestones, and applying deliberate tactics to manage certification cost and time, organizations can transform certification from a risk into a competitive advantage.
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