Leeham News and Analysis
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Bjorn’s Corner: Faster aircraft development. Part 28. Development times.
By Bjorn Fehrm and Henry Tam
February 20, 2026, ©. Leeham News: We have, since August 2025, gone through an FAA CFR 14 Part 25 development project of an airliner in the 200-seat class. The aim was to identify the activities required for such a project and the regulatory actions needed to achieve Type Certification (TC) and Production Certification (OC) for the aircraft.
The program followed the time plan in Figure 1, which indicated that it would take about seven years from the start of conceptual design to deliver the first aircraft and enter service (EIS). At each phase, we assessed whether modern support techniques, such as AI, could help with development and certification and whether they would accelerate the program plan.
Figure 1. A typical Program Plan for a smooth-running Part 25 airliner development. Source: Leeham Co.
We now summarize the findings and incorporate additional modern support, such as Digital Twin support, to assess the overall impact of today’s technologies on the program plan timeline in Figure 1. Read more
Bjorn’s Corner: Faster aircraft development. Part 27. Where Speed-Up gets Tough.
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.
Bjorn’s Corner: Faster aircraft development. Part 26. AI speeds up processes.
By Bjorn Fehrm and Henry Tam
February 6, 2026, ©. Leeham News: We have completed a detailed, step-by-step analysis of the certification requirements a Part 25 Air Transport airliner in the 200-seat segment must meet.
In our series, we have seen work that could benefit from an AI agent, and other work where we conclude it will be difficult.
We begin this week by outlining areas where we expect AI to reduce the number of work hours required to complete a task. We will attribute these AI-driven work-hour reductions to the appropriate areas of the aircraft Program Plan in Figure 1.
Figure 1. A generic new Part 25 airliner development plan. Source: Leeham Co. Click to see better.
Outlook 2026: The airliner projects that promise new technology and lower emissions
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By Bjorn Fehrm
February 5, 2026, © Leeham News: We survey new entrants that deviate from the classical gas-turbine tube-and-wing airframe concept and offer airliners the promise of lower emissions and, hopefully, lower costs.
We will do this by starting with those closest to certification and delivery, then tapering off to those who currently fly on PowerPoint.
If we didn’t apply this filter to what we consider real projects, we would describe over 50 entries, with additional ones announced with airline orders every month over the last few years. Few of these have progressed beyond plans, which is why we focus on those that have.
Overall, it’s amazing that 11 years after the Airbus E-fan battery-electric aircraft flew at the Farnborough Air Show in 2014, we still do not have a single certified alternative-propulsion passenger aircraft. We have one light-sport two-seat trainer, the Pipistrel Electro Velis, but nothing else.
Figure 1. The Airbus E-Fan at the Paris Air Show in 2015. Source: Wikipedia.
Bjorn’s Corner: Faster aircraft development. Part 25. The Difference between Continuing and Continuous Airworthiness.
By Bjorn Fehrm
January 39, 2026, ©. Leeham News: We have done a series about ideas on how the long development times for large airliners can be shortened, while at the same time describing all the regulatory work that must be done, regardless of work practices.
It’s now time to sum up what we have looked at in terms of speeding up the development of a Part 25 Air Transport airliner in the 200-seat segment. But before we do that, we will look at what an operator of the aircraft we have delivered will have to do to qualify it for operation with its local regulator.
For an operator to operate our aircraft, Continued Airworthiness, as described in last week’s article, is not enough; the Operator must add what can be called Continuing Airworthiness. These words are close but not the same, and there is a substantial difference in what’s behind them.
Pratt & Whitney builds for the future while wrestling with the present
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By Bjorn Fehrm and Charlotte Bailey
January 26, 2026, © Leeham News: Pratt & Whitney (PW) bet big on the geared turbofan to take it back to a sizeable position in the market’s largest airliner segment, the Single-Aisle. It spent more than 20 years to develop the fan gearbox, including functional demonstrator engines that flew on Airbus test aircraft to prove the technology.
The effort was a success; the gearbox in the Pratt & Whitney range of Geared TurboFans, GTFs, has worked perfectly. It achieved what was promised, a low fuel consumption, and has been rock-solid in its function.
Yet PW’s GTFs have had a range of problems since their introduction in 2016. Bent main shafts, combustors that burn through, bearings that fail. And on top, a huge call-back of engines, as a contaminated power metal process has produced compressor and turbine discs that risk failing before their on-engine life expires. The situation has caused over 600 Airbus A320 and A321neos with GTF engines to be grounded for engine replacements, if and when replacement discs are available.
The issues, stemming from the “business as usual” parts of the GTF, have led to write-offs of billions of dollars for PW’s mother RTX and to lost market share to the competing CFM LEAP engine on the Airbus A320/321neo series. But while this clouds the business of yesterday and today, Pratt & Whitney still has the clout to invest in the future. Being part of one of the World’s largest Defence and Aerospace Companies is an important part of the answer.
Figure 1. The Maeve MJ500 with the revolutionary Pratt & Whitney Canada Constant Volume Open Fan engine. Source: Maeve. Read more
Bjorn’s Corner: Faster aircraft development. Part 24. Post certification, Sustainment phase.
By Bjorn Fehrm and Henry Tam.
January 23, 2026, ©. Leeham News: We do a series about ideas on how the long development times for large airliners can be shortened. New projects talk 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. We have looked at the preparation work around entry into service; now we talk about post-certification work and the support of the new airliner generating revenue flights for the airline customer.
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 **
Bjorn’s Corner: Faster aircraft development. Part 23. Preparing for Entry Into Service.
By Bjorn Fehrm and Henry Tam
January 16, 2026, ©. Leeham News: We do a series about ideas on how the long development times for large airliners can be shortened. New projects talk 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. We have looked at the production preparations and the challenges of the serial production phase. Now we look a the preparation work around entry into service for our new airliner.
Figure 1. A generic new Part 25 airliner development plan. Source: Leeham Co. Click to see better.
Bjorn’s Corner: Faster aircraft development. Part 22. Serial Production.
By Bjorn Fehrm and Henry Tam.
January 9, 2026, ©. Leeham News: We do a series about ideas on how the long development times for large airliners can be shortened. New projects talk 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. We have completed flight testing of the flight test aircraft and obtained a design Type Certificate (TC). We now examine the production preparations and the serial production phase.
Figure 1. A generic new Part 25 airliner development plan. Source: Leeham Co. Click to see better.
Bjorn’s Corner: Faster aircraft development. Part 20. Flight Testing.
by Bjorn Fehrm and Henry Tam
December 12, 2025, ©. Leeham News: We do a series about ideas on how the long development times for large airliners can be shortened. New projects talk 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. We have completed the articles on Prototype Manufacturing and Ground Vibration Tests (GVT). We now conduct the program’s flight tests with the manufactured test aircraft.
Figure 1. A generic new Part 25 airliner development plan. Source: Leeham Co. Click to see better.