The Federal Aviation Administration recently announced that it would begin to audit the production of Boeing’s 737 MAX 9 aircraft. The FAA’s decision to provide increased scrutiny of Boeing’s assembly process follows the infamous failure of an exit door plug onboard Alaska Airlines flight AS1282. With more eyes looking at the building process, it’s worth asking: How are aircraft built?
The process of aircraft assembly will change with aircraft size and complexity. Each design will further have its own unique demands and methods. While aircraft complexity has increased for commercial airliners, manufacturers have changed their assembly methods over the years by developing new technologies.
Starting small is building general aviation aircraft. For producing such aircraft, by the numbers, a sizable portion of newly built planes are amateur-built and assembled by individuals. According to the Experimental Aircraft Association, the Federal Aviation Administration has certified more than 33,000 amateur aircraft in the United States. In comparison, a total of 1,140 piston-driven aircraft were delivered worldwide between January through September 2023, a 10% increase from deliveries a year earlier.
Building an aircraft at home, in most cases, requires building from a kit. Builders will place their order with an aircraft manufacturer and receive plans and materials for their desired building locations — either at home or in a hangar. For example, one of the most successful kit-built aircraft models is the Vans RV-12. Since 2008, the light sport aircraft type has received orders for more than 1,100 kits, according to the aircraft’s designer. The RV-12 building process can take years or months to complete depending on the builder’s skill level and time commitment.
When building an RV-12, builders are supplied with kits from the aircraft designer split into sections: empennage (tail and aft fuselage), fuselage, avionics, engine, wings, and finish kits. These kits mostly contain aluminum sheets with prefabricated holes to be match-drilled by the homebuilder. Homebuilders will then rivet aluminum sheets together to build the aircraft. FAA regulations require homebuilders to assemble at least 51% of their aircraft.
Moving up in size from piston-driven aircraft includes glamorous, complex private jets capable of transiting continents and oceans at speeds and altitudes faster and higher than their larger commercial airline rivals. For example, one of the largest business jets is the Gulfstream G700, a twin-engine jet that can reach speeds of Mach of 0.935 and has a price tag of more than $78 million. Gulfstream completed the construction of its newest production facility in October 2023, providing some insight into the aircraft’s construction.
Unlike the RV-12, which only requires 420 square feet to build one unit, Gulfstream’s new production facility in Savannah, Georgia, is 142,000 ft². While homebuilt aircraft like the RV-12 can be made with as little as one person, the G700 production created more than 1,600 new jobs at Gulfstream, in addition to more than 12,000 people already working for the private aircraft manufacturer, according to local reports.
In this facility, large aluminum and composite components are placed into jigs and moved through various plant areas, where workers will install various sub-components and utilize robots and machines to rivet them together. Gulfstream has specifically changed how it builds aircraft, relying on bonded stringers and other assembly methods to reduce the number of rivets used to produce its aircraft. In some cases, aircraft components are baked together, using ovens to bond components together at higher temperatures.
As you might expect, with the increased size of the company and aircraft comes more complexity. Boeing has become famous for using sub-components from other companies, such as Spirit Aerosystems. These sub-components are then brought to final assembly facilities to be machined together. Boeing taps over 12,000 employees on the final assembly 737 at its Renton, Washington, facility, where it builds the 737.
After receiving the fuselage, flaps, tail, and other sub-components from Spirit Aerosystems, a 737 can be assembled in as little as nine days. The first three days are spent connecting electrical and hydraulic systems inside the aircraft’s fuselage before it can be joined with the wings. The 737’s wings are assembled by Boeing at a separate facility in Washington using various parts from a series of other sub-contractors. After the wings are installed using precision lasers, the landing gear and engines are attached to the airframe.
Source: simpleflying.com