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.

Serial Production

Crossing the type certification finish line is a great achievement.  It is a tangible result that the team should celebrate.  Yet, an OEM does not make money by certifying an aircraft.  It needs to produce aircraft and deliver them to customers to generate revenue.

Production Certification

The manufacturing team needs to obtain a Production Certification (PC) from the Regulator so the OEM can obtain an airworthiness certificate for the production aircraft without submitting every detail of each produced aircraft to the authorities for approval, given that the product has achieved a Type Certificate (TC).

To obtain the Production Certification, the manufacturing organization must demonstrate its ability to control and manage data/documents, suppliers, manufacturing processes, inspections/tests, and nonconforming parts. The OEM needs to demonstrate that it can produce what it plans to produce, manufacture products in a repeatable manner, and address in-service issues and quality escapes.

Processes associated with a Production Certification are required early on, as many are already applicable during the assembly of a conforming flight test aircraft.  For example, a Product Lifecycle Management (PLM) system helps control data and documents. To control them, a set of processes needs to be defined.  Simple concepts, such as roles and responsibilities, approval workflows, change control, etc., need to be documented and implemented before Preliminary Design to prevent miscommunications.

Some of these processes can meet the obligations of both the Type Certificate holder and the Production Certification holder. Therefore, it is a good idea to establish Production Certification-related processes early on so that the OEM can use the flight-test assembly process to gather production data and present these to the Regulator to help build confidence.

Start of Production

OEMs often run into a dilemma at this stage.  If the company wants to deliver the aircraft shortly after type certification, it needs to kick off the serial production at the start of the flight test phase.  Starting production too early has some risks.  If changes are required due to discoveries during the flight test program, the first few aircraft may require rework to install parts conforming to the type design. This comes on top of the excess cost of early aircraft due to the manufacturing learning curve (see below).

On the other hand, management usually does not have the luxury to wait for the aircraft to be fully certified before starting serial production. After investing heavily in the development program, shareholders want to see aircraft delivery revenue as soon as possible. Striking the right balance is crucial to the program’s success.

The Production Learning Curve

A phase in the development and introduction to the air transport market that is consistently underestimated is the additional program costs associated with early deliveries driven by the Production Learning Curve.

Knowledge about the Production Learning Curve spans more than 100 years of aircraft production. The manufacturing learning curve means that early parts and systems take longer and thus cost more to manufacture than those later in the serial production phase.

The first units of a typical 200-seater airliner production line could cost more than three times as much to produce as aircraft that are made at so-called mature costs. The typical Manufacturing Serial Number (MSN), where a project has reached mature costs, is after 300 to 400 units have been built.

The New Aircraft Program Triple Whammy

A new aircraft program is typically hit by three cost factors that are often underestimated:

• Development costs that exceed planned levels.
• Initial production costs that are higher than planned.
• Launch customer pricing at higher discounts than foreseen.

We have described development costs and initial production costs. The liquidity stress on the program combines these two with launch customer pricing.

Early customers of a new aircraft take a risk by ordering the aircraft. The market success of the plane is not yet assured, and you don’t want to take delivery of an airplane where you risk becoming one of only a few customers.

Aircraft programs, therefore, secure large, influential first customers who order a large number of aircraft, giving subsequent customers the impression that the program will be successful. To place these large initial orders, the launch customers demand very favorable pricing. This means net revenue for the initial 50 to 100 aircraft is considerably lower than for later-delivered aircraft and well below manufacturing cost.

The lower-than-normal net revenue, combined with the extra production costs of the first 200+ produced aircraft and any additional development costs, creates a very challenging liquidity situation for most programs.

If production ramp runs meet program expectations and the initial production cost has been properly estimated, the strain on program liquidity will remain manageable.

But if early deliveries are delayed and occur more slowly than planned, the strain on program liquidity can cause programs to fail. It’s often the case for new aircraft startups. These are often investor-funded, and there is limited awareness that the program’s total funding usually exceeds early estimates by more than 50%. At the same time, net revenue is lower than expected due to launch-customer pricing and a slower-than-planned production ramp.

Historically, new aircraft programs fail, not at type certification but before or around the first 100 aircraft are built, when investors run out of money and patience.

Why is there a Learning Curve, and what can be done about it?

An airframe in the 200-seater class is made up of more than two million parts. Some of these are standard parts, such as rivets, fasteners, pipe joints, and electrical connectors. But hundreds of thousands of parts are uniquely designed or modified for the new aircraft.

The production of these parts requires a lot of reading of drawings and instructions, discussing, and checking by production mechanics and production engineers during the early production runs. Because production of aircraft parts and systems is labor-intensive, the extra work hours typically increase production costs to over three times the serial cost calculations, which are usually estimated at MSN 300 to 400.

These costs are then reduced by the learning-curve factor as production continues. Each build group of the aircraft has its own learning curve, but a rule of thumb repeatedly validated in the industry shows that an airframe’s overall production cost decreases by about 15% for each doubling of the Manufacturer’s Serial Number, the MSN.