Leeham News and Analysis
There's more to real news than a news release.
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 21. Certification Implementation.
By Bjorn Fehrm and Henry Tam
December 19, 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 concluded the articles about flight tests with the aircraft. Now we revisit the Certification subject and look at how we can show compliance with requirements and work our way to a Type Certificate. We are at the end part of the Testing and Certification phase in our Program Plan in Figure 1.
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 19. Flight Test Aircraft Assembly.
December 5, 2025, ©. Leeham News: We do a series on ways to shorten the long development times for large airliners. New projects aim to cut development time and achieve 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 the different approaches to reducing development time.
We will use the Gantt plan in Figure 1 as a base for our discussions. We have exited the Detailed Design phase after conducting Critical Design Reviews, CDRs, and now enter into Prototype Manufacturing. After reviewing the acceptance and testing of the first parts and systems from suppliers, we now discuss putting together the first flight-test aircraft.
Figure 1. A generic new Part 25 airliner development plan. Source: Leeham Co. Click to see better.
** Special thanks to Ron Everlove for helping with this article **
Bjorn’s Corner: Faster aircraft development. Part 18. Prototype Parts and Systems.
By Bjorn Fehrm and Henry Tam.
November 28, 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 exited the Detailed Design phase after conducting Critical Design Reviews, CDRs, and now enter into Prototype Manufacturing.
Figure 1. A generic new Part 25 airliner development plan. Source: Leeham Co. Click to see better.
** Special thanks to Ron Everlove for helping with this article **
Bjorn’s Corner: Faster aircraft development. Part 17. Critical Design Review, CDR.
By Bjorn Fehrm and Henry Tam
November 21, 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 are in the Detailed Design phase, and it’s time to conduct the Critical Design Reviews, CDRs.
Figure 1. A generic new Part 25 airliner development plan. Observe the CDRs. Source: Leeham Co. Click to see better.
Bjorn’s Corner: Faster aircraft development. Part 16. Certification Compliance Planning.
By Bjorn Fehrm and Henry Tam
November 14, 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 are in the Detailed Design phase and working with the Certification Compliance plan.
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 14. Detailed Design.
October 31, 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 exited the Preliminary Design phase through the Preliminary Design Reviews, PDRs, and now enter the Detailed Design 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 13. Preliminary Design Review, PDR.
By Bjorn Fehrm and Henry Tam
October 24, 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. Today’s topic, the Preliminary Design Reviews, PDRs, are marked in the chart.
Figure 1. A generic new Part 25 airliner development plan with PDR marked in time. Source: Leeham Co. Click to see better.