By Bjorn Fehrm and Henry Tam
September 12, 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.
Conceptual Design
After receiving the go-ahead from the company in the Feasibility phase, we can start forming a more structured team for the Conceptual Design. At this stage, it is necessary to formulate high-level approaches for several critical areas, such as aircraft design, supply chain planning, manufacturing strategies, certification, and other essential topics.
The Importance of a Thorough Conceptual Design
According to the NASA Systems Engineering Handbook, about half of the life-cycle cost is expected to be committed by the end of this phase ( Figure 2).
Figure 2. The importance of thorough work in early project phases. Source: NASA.
The cost of changes will also grow rapidly after the concept phase. Even though these numbers and the definition of each phase vary from organization to organization, the importance of this phase should not be underestimated.
Aircraft Design in this phase
Many activities need to progress in parallel at this stage. We already have an idea of the aircraft’s overall data and shape from the feasibility study. The structures team now needs to come up with a layout. The systems teams need to follow the development process to start defining various systems. The engineering sciences team members (such as aerodynamicists, stability & control engineers, aircraft performance experts, etc.) need to begin generating data to support the design and trade-off studies.
Once a sufficiently defined concept is established, the teams can release initial datasets, such as loads, to facilitate the next design iteration. The engineering sciences team may also want to conduct wind tunnel tests to de-risk the design. For example, the team would obtain test data on stall characteristics and compare them with the computational fluid dynamics (CFD) predictions.
Systems also need to mature. We will, in the next Corner, go into more detail about system definition and development.
The interior is an important consideration as well. This is where an OEM and its customers (a.k.a. airlines) generate brand loyalty with passengers. This is also where many tradeoffs need to happen. For example, assume the aircraft could accommodate 200 seats. If we could shave 1 kg from each seat, we could save 200 kg. This means more payload, longer range, or improved fuel efficiency. This could go in the opposite direction as well. We might end up adding 1 kg per seat to improve the functionality of the seats.
Again, aircraft design is an iterative process. There will be many studies and configuration refinements during this period. All decisions are documented. Many requirement documents are drafted. Initial CAD models are created. Engineering collaborates with Supply Chain and Manufacturing for the activities discussed below. Engineering also receives feedback from the Supply Chain and Manufacturing to refine the design.
Supply Chain Considerations
It is unlikely that an OEM would want to, or be able to, design everything itself. Depending on its existing capabilities and willingness to invest in new areas, it may decide to outsource some of the work packages to suppliers. The business team, with support from other functions, needs to conduct make/buy analyses. The team must develop and execute a plan to engage, select, and onboard suppliers for the right scope and at the right time. This is a complex task because it involves many internal and external stakeholders. It also involves a lot of money.
For instance, if a system costs one million dollars per shipset, and we plan to produce 1,000 units, it becomes a one-billion-dollar contract. This is why the supply chain team usually wants to understand the supplier’s financial standing at this stage. An aircraft OEM may not want to do business with a financially weak company.
An OEM also does not want to do business with a company that does not understand aerospace quality control requirements. Hence, the Quality team needs to support the selection effort. This team conducts audits to ensure that suppliers can meet quality requirements (such as, but not limited to, process control, configuration control, quality escape management). It provides valuable inputs to the supplier selection process.
Manufacturing Considerations
Manufacturing is another important area. For this article series, we want to narrow the manufacturing scope to final assembly. The manufacturing team does not need details at this stage, but needs an idea about the production system, the space required, and special facilities requirements. For example, setting up a paint hanger may require an environmental assessment. This could be a challenge in certain regions.
The team may also need to explore the location of a new manufacturing site. Land availability, logistics, and workforce availability and readiness are just a few considerations. Some manufacturing topics need to be considered up front because they require high capital expenditures. They could also impact the supply chain.
Manufacturing engineers also provide input to aircraft design. For instance, do we want a one-piece, two-piece, or three-piece wing? Each design has its pros and cons from a weight, assembly time, and logistics perspective (Figure 3).
Figure 3. The design of the wing is important not only for aerodynamics but also for logistics. Source: Wikimedia Commons.
The team may not be able to select the final solution at this stage, but they could eliminate some nonviable or less desirable options. This is why manufacturing’s involvement is essential.
Certification Work
Certification is a part of the development process, not an afterthought. During this phase, the company must initiate some of the work related to certification. We will go into more detail about certification activities during Conceptual Design in a coming article.
Additional Challenges for Startups in This Phase
In addition to the topics discussed above, start-ups also need to do a significant amount of background work. For example, the team needs to establish many processes, such as data control, configuration control, and change management. These processes are crucial for designing an aircraft. They ensure all teams are working on the same assumptions. Imagine the wing team just updated the design of the wing, call this new design wing_rev_B. In parallel, the high-lift team is updating attachments to the wing using wing_rev_A. This could be a frustrating experience and a non-value-adding exercise. Without proper processes and procedures, the project will become unmanageable very quickly.
Speeding Up the Conceptual Design Phase
There are opportunities to use emerging technologies to reduce work hours for aircraft Conceptual Design. For example, generative AI can help create a rough draft for some of these documents or analyses. Mature OEMs can feed previous designs and analyses into the machine and ask it to generate rough drafts. Engineers responsible for these analyses will still need to review, update, and refine them to ensure correctness. Engineers also still need to be able to explain results to the authorities.
The ability to tie requirements, designs, analyses, schedules, etc., in a streamlined fashion can also save work hours. Team members spend less time chasing answers, consolidating data, and generating reports, reducing the number of people required to support the program.
On the supply chain side, emerging tools could help evaluate supplier bids. AI might assist in analyzing internal historical data and new bid packages to provide down-select recommendations. It may also help automate some of the communications. However, using AI agents to communicate with suppliers might also have disadvantages. Human-to-human engagement helps build rapport. These relationships are valuable in resolving issues over the life of the program. Robot-to-robot engagement, for this use case, may reduce work hours in the short run but may not yield the same results in the long run.
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