Spirit AeroSystems

When you photograph a 737 at the fence, you most likely have a fuselage from Wichita in front of your lens. Spirit AeroSystems built it, as well as the noses of many Boeing widebody jets, the wings of the A220 and fuselage sections of the A350. For almost two decades Spirit was the largest independent manufacturer of aircraft structures in the world, a supplier without which neither Boeing nor Airbus could have kept up their production. In December 2025 this story ended: Boeing bought Spirit back, and Airbus took over the plants that work for its programs. This profile explains how it came to this and where you can find Spirit’s work again as a spotter.

From Boeing plant to independent supplier

Spirit’s story begins long before the company name. In 1927 the plant of Stearman Aircraft was created in Wichita, Kansas, later absorbed into Boeing. As Boeing Wichita, the site built strategic bombers in the Second World War and the Cold War, including the B-29, the B-47 and the B-52. Over time Wichita became the center of fuselage production for Boeing’s airliners.

In 2005 Boeing decided to give up this part of the value chain. The company sold the plants in Wichita as well as in Tulsa and McAlester (Oklahoma) to the Canadian financial investor Onex, with an enterprise value of around US$1.2 billion. The new company started as Mid-Western Aircraft Systems and after a few months was called Spirit AeroSystems. The goal was to become more independent of Boeing and win customers outside the old parent company.

That succeeded quickly. In 2006 Spirit bought BAE Systems’ aerostructures business at Prestwick Airport in Scotland, bringing Airbus work into the company. In November of the same year the company went public. In 2010 Spirit opened the composite plant Kinston in the US state of North Carolina, built for fuselage parts of the then-new Airbus A350. Added to this was production in Saint-Nazaire on the French Atlantic coast and, already from 2009, in Subang, Malaysia.

The largest acquisition followed at the end of the decade. In 2019 Spirit agreed with Bombardier to buy the structures plants in Belfast and Casablanca, and in 2020 the deal was completed. The Belfast plant goes back to Short Brothers, one of the oldest aircraft manufacturers in the world. The Skyvan, the Shorts 330 and the Shorts 360 were once built there, later under Bombardier management components for regional and business aircraft – and the wings of the A220, which had been developed as the Bombardier CSeries.

What Spirit built for Boeing

The heart was always the 737. According to common reference works, around 70 percent of the bestseller’s structure comes from Wichita, above all the complete fuselage. Fully assembled, but without wings, engines and paint, the fuselages travel by rail to Washington State, where Boeing takes over final assembly in Renton. Whether a 737-800 at Ryanair, a 737 MAX 8 at Southwest or a 737 MAX 9 at Alaska: the fuselage comes from the same hall in Kansas.

On the widebody aircraft Spirit concentrated on the nose and cockpit sections. The noses of the 767, the 777 and the 787 were built in Wichita, plus wing and engine components for practically all Boeing airliners. The military derivatives benefited too: the fuselages of the P-8 Poseidon and the tanker KC-46 Pegasus are based on civil types and therefore also went through Spirit.

The strong dependence was mutual. Boeing was by far Spirit’s largest customer, and Spirit in turn was the bottleneck on which 737 production hung. Whenever something went wrong in Wichita, final assembly in Renton came under pressure shortly afterward. This entanglement determined the company’s last years.

What Spirit built for Airbus

Less well known, but just as important for Airbus, was the European and North American Airbus business. In Kinston and Saint-Nazaire, fuselage sections for the A350 were built, which then went to Toulouse for final assembly. Saint-Nazaire is one of the classic Airbus sites served by the BelugaXL – one reason why the transport jet is so present among spotters in western France. You can read more about final assembly in the article Plane spotting in Toulouse-Blagnac.

In Prestwick Spirit made components for the wings of the A320 family and the A350, in Belfast the complete wings and the center fuselage of the A220. In Wichita the engine pylons of the A220 were also built, and in Casablanca components for the A321 and A220. That made Spirit involved in almost all current Airbus programs, on the A220 even in wings, fuselage and pylon at the same time.

When the supply chain stalled after the pandemic, it hit Airbus noticeably. Problems with fuselage parts were among the reasons Airbus programs were delayed; on the page for the A350F you’ll find an example of how closely such supplier issues are tied to the schedules of new types.

Quality problems and the Alaska incident

Spirit’s reputation suffered in the late 2010s and early 2020s from recurring quality reports. Wrongly drilled holes, incorrectly installed components and rework on 737 fuselages slowed deliveries several times. Financial losses were added: for 2024 Spirit reported a net loss of over two billion dollars on revenue of around US$6.3 billion.

The turning point was January 5, 2024. Shortly after takeoff in Portland, a so-called door plug came off an Alaska Airlines 737 MAX 9, a panel that in certain cabin configurations seals an unneeded emergency exit behind the wing. The cabin lost pressure suddenly, the aircraft turned back and landed safely; everyone on board survived.

Spirit had built the fuselage and the door plug. At Boeing’s Renton plant the plug was later removed so that Spirit employees could repair damaged rivets, and then reinstalled without the four securing bolts. In its 2025 final report, the US accident investigation agency NTSB saw the probable cause mainly in Boeing’s manufacturing processes and in insufficient oversight by the FAA. For public perception, though, one thing counted above all: the division of labor between Wichita and Renton had obvious gaps.

The buyback: Boeing and Airbus split Spirit

Talks about a buyback began as early as the beginning of 2024. By midyear 2024 the agreement was there, made public on July 1: Boeing takes over Spirit in a stock swap, with an equity value of around US$4.7 billion, around US$8.3 billion including debt. Spirit was led in this phase by Patrick Shanahan, who had worked at Boeing for about three decades and had headed Spirit since fall 2023.

The problem: a large part of Spirit’s work belonged to the competition. Airbus could have no interest in plants for the A350 and A220 falling to Boeing. In parallel to the Boeing agreement, Airbus therefore signed a binding letter of intent, and the final agreement followed on April 28, 2025. Spirit paid Airbus compensation of US$439 million, and Airbus in return provided interest-free credit lines totaling US$200 million for the transition period.

On December 8, 2025 Boeing completed the acquisition. According to company figures, around 15,000 employees joined Boeing. The civil business was integrated into the commercial airplanes division, the spare parts business into Boeing Global Services. The defense business continues as Spirit Defense, independently run, but linked to Boeing’s defense division for reporting purposes. In Belfast Boeing took over the parts of the plant that do not work for the A220; since then they operate as an independent subsidiary under the name Short Brothers – A Boeing Company.

Where you see Spirit’s work as a spotter

None of the components carries a logo, but Spirit’s traces are everywhere. The simplest rule of thumb: every 737 of the last decades has a fuselage from Wichita. That applies to the Classic and NG fleets as well as the MAX, that is, to a considerable part of what takes off and lands daily at European airports – from Ryanair to the leisure airlines.

With a little background knowledge the look gets sharper:

If you travel to the USA, you get closest to the Boeing world in the Seattle area. You won’t see the fuselages from Wichita on the apron there, but at the Future of Flight in Everett and in the Museum of Flight at Boeing Field you get a good impression of how Boeing aircraft are made from many supplier parts. You can track newly delivered aircraft with the article on delivery and ferry flights.

Spirit compared

Spirit was not the only structures builder, but the largest independent one. The obvious comparison in Europe is Premium Aerotec, which also emerged from an aircraft builder’s production but, unlike Spirit, stayed in the Airbus group. Other large suppliers such as Leonardo, Collins Aerospace or Safran cover structures, nacelles or systems, but never stood as centrally for a single bestseller as Spirit did for the 737. In the cabin, Diehl Aviation supplies.

Spirit’s return to Boeing is seen in the industry as a turn away from the outsourcing strategy of the 2000s. Instead of sourcing core components from external suppliers, both big manufacturers are pulling critical production back closer to themselves. Which differences between the two groups’ aircraft you can see from the outside in the end is shown in the article Telling Airbus and Boeing apart.

Conclusion

For around twenty years Spirit AeroSystems was the invisible partner behind the world’s most-built airliners. From the old Boeing plant in Wichita grew a supplier that, with Prestwick, Kinston, Saint-Nazaire, Belfast and Casablanca, also became indispensable for Airbus. Quality problems, financial losses and the Alaska incident ultimately led both big manufacturers to take their parts back.

For you as a spotter Spirit stays present all the same: in every 737 fuselage, in the noses of the 767, 777 and 787, in the wings of the A220 and in fuselage sections of the A350. Anyone who knows where these parts come from will look a little more closely at the next photo subject.