By Bjorn Fehrm and Henry Tam.

February 13, 2026, ©. Leeham News: We are summarizing how modern tools, processes, and AI can help reduce the time required to develop a clean-sheet 200-seat replacement for the Airbus A321neo and the Boeing 737 MAX 10.

We discussed some ideas in the last article on how current AI can support development.  We could see it helping reduce the time spent on templating documents and on designing and verifying simple parts, such as mounting brackets for pipes and cables.

To address the more challenging parts where AI struggles to assist, we need to understand why development programs now take longer than in the past and what can be done to shorten the timeline.

Here are examples of challenges that meet today’s Part 25 aircraft development projects:

Use of Advanced Material

Many programs today are using new composite materials to reduce weight. On the one hand, these materials typically have better properties than traditional materials, and costs would come down once the tooling is paid off.  On the other hand, certifying new materials is often not as simple as expected.  It often takes years to characterize these materials and manufacturing processes.

Composite materials qualification typically involves thousands of test articles to statistically characterize the material.  A range of tests, from small test coupons to full assembly, is required.  The processes used to produce these parts must also be controlled and documented in the materials qualification dataset.

The National Center for Advanced Materials Performance (NCAMP) maintains a pre-qualified materials list to reduce the number of tests required.  OEMs that choose to use these material specifications must adhere to the design constraints and manufacturing processes when developing parts from these materials.  If OEMs deviate from the material specifications, additional tests are required.

We shall compare this to designing yet another aluminium airliner, like when Boeing went from the 727 and 737 to the 757/767. Essentially, the same material system was used for the different parts, sometimes with modest updates. But it wasn’t as drastic a change as going from Aluminium Alloys to Carbon Composites for a part of the aircraft. The bottom line is that an aluminium structure is faster and cheaper to develop and produce, though it is less beneficial in terms of weight and maintenance costs.

Widespread Use of Advanced Electronics

Modern aircraft have numerous onboard smart electronic systems.  The traditional pitot-static system has been replaced by smart probes.  The avionics system is now the aircraft’s brain, with access to every system.  Flight controls on new airliners are all fly-by-wire.

There is a cost to using these advanced electronics, especially in safety-critical systems.  Software for these systems must follow the processes outlined in DO-178, Software Considerations in Airborne Systems and Equipment Certification.  This is not a black-box test that a developer can do at the end of the development.  The design must be fully traceable.

Safety-critical software has even more stringent requirements, such as Object Code Verification.  This requires traceability from source code to machine-understood low-level code.  If traceability cannot be demonstrated directly, additional verification is required.

As with software systems, complex electronics also need to be qualified under DO-254, Design Assurance Guidance for Airborne Electronic Hardware.  The guidance applies to a wide range of components, including circuit board assemblies and integrated circuits.  The design must undergo a rigorous validation and verification process.  Again, a black-box test at the end of development is not acceptable, especially for safety-critical systems.

From this, we can see that a major change in an advanced electronic system could have a significant impact on work time due to verification and validation.  Regression tests often consume a non-trivial amount of time.

Electric Wiring Interconnection System (EWIS)

Wiring has also gotten more complicated over time.  Part of the complexity stems from the widespread use of advanced electronics.  More wires are needed to connect components to the “brain”.  This also leads to more complex failure analyses.  Can a rotor burst, a tire burst, a local fire, etc., damage wiring in a way that the aircraft cannot achieve a safe flight to landing?

A safety engineer can work with their systems and structures counterparts to physically separate redundant systems.  However, this strategy does not work if a rotor burst could sever all the wires to these redundant systems.

Another part of the complexity comes from lessons learned.  Some regulations grew out of an aircraft explosion thought to have been caused by wire shorts igniting fuel tank vapour, and damage to the aircraft caused by wiring faults (sometimes originating in non-essential systems).

One common yet critical challenge with EWIS on a development program is that the team often receives numerous late changes for various reasons, even though they must deliver parts early so wiring bundles can be buried deep inside the airframe.

Regulatory Interaction and Oversight

Highly advanced/integrated systems and novel materials often lack established methods for demonstrating compliance with applicable regulations.  To establish the means of compliance (MOC), the OEM and the regulator often engage in extensive back-and-forth communication to discuss the technology and its features, develop an MOC, and document the agreement through Issue Papers.

These coordination activities with the authorities often take months to close.  It is also not unusual to have multiple sets of MOC Issue Papers for a development program.

When the regulator determines that current rules do not adequately address a new technology, the OEM and the authorities often engage in a multi-year process to develop Special Conditions to address the gaps.  Unlike Issue Papers, Special Conditions establish regulatory requirements.

As a result, Special Conditions are subject to public comment, which may lead to a lengthy closure period.  For example, the Notice of Proposed Special Conditions for magniX’s electric engines was released in November 2020 (https://www.federalregister.gov/documents/2020/11/19/2020-23434/special-conditions-magnix-usa-inc-magni250-and-magni500-model-engines).

The Final Special Conditions were released in September 2021 (https://www.federalregister.gov/documents/2021/09/27/2021-19926/special-conditions-magnix-usa-inc-magni350-and-magni650-model-engines-electric-engine-airworthiness). This is almost a year of waiting for the requirements to which the motor shall be developed.

Interagency coordination is another challenge.  When validating a type design with foreign authorities, the foreign authorities may deem the agreed Menas Of Compliance (MOC) inadequate.  If this is addressed early on, it may not be a big deal.  However, if this is done after certification, it could require costly changes to obtain the desired foreign validation.

Summary

The above lists reasons why the typical development time for a new airliner in the A320/A321 and 737 class now takes two years longer than for 40 years ago when the A320 was developed. We will summarize the impact of modern integrated tool support, such as the Digital Twin, Agile methodologies, and AI, next week.