A lot of work goes into assembling modern airplanes. A typical commercial airliner has millions of individual parts. Depending on the size, it can take anywhere from weeks to months to assemble them. While some of these parts are small, others are quite large, such as keel beams.
What Is a Keel Beam?
A keel beam is a structural beam that runs along the bottom of an airplane’s fuselage. It’s used to support and connect other components, including the wing box, landing gear and fuselage frames.
Most airplanes have two keel beams. One of the keel beams is located in the right-center of the fuselage, whereas the other is located in the left-center. Together, they form the backbone of modern airplanes by holding the fuselage together.
Load Handling
Unlike many other structural parts, keel beams are designed to handle concentrated loads. They are regularly exposed to strong forces during flight and on the ground. The wings, for instance, generate lift during flight, which creates upward aerodynamic forces.
On the ground, the airplane’s landing gear transfers impact forces directly to the fuselage. Landings create some of the strongest forces to which airplanes are exposed — sometimes as much as two to three times the airplane’s total weight. Keel beams must be able to withstand these forces to protect the airplane’s structural integrity.
Load Distribution
Keel beams work by distributing loads across a larger area. Whether in the air or on the ground, airplanes are regularly exposed to concentrated loads. As the main body of an airplane, the fuselage typically absorbs these loads.
Keel beams protect the fuselage and supporting components from stress-related damage by distributing loads across a larger area. Rather than being isolated to a specific section of the fuselage, loads are spread out The end result is reduced stress concentration and a lower risk of fatigue cracks and related damage.
What Are Keel Beams Made Of?
You can find keel beams made of different materials. Aluminum alloy is probably the most common. Keel beams made of aluminum alloy offer an excellent strength-to-weight ratio. Aluminum alloy weighs less than many other materials, but it’s still very strong and able to handle heavy loads.
In addition to aluminum alloy, titanium may be used for keel beams. It’s heavier than aluminum alloy but offers a superior level of strength and durability. There are also composite keel beams. Consisting of advanced materials like carbon fiber or glass, they are becoming more common, particularly in new airplanes.