How Are Engines Attached to Aircraft?
Just like with each part of an aircraft, the placement of the wings has been carefully chosen with considerations to safety and efficiency. On most commercial planes, they are placed in pods under the wings and mounted at a small distance by way of a pylon. This has become the standard engine attachment for all large commercial aircraft for several crucial reasons, all of which are explained in detail below.
Why Are Most Engines Placed in Pods Below the Wings?
Most commercial aircraft have their engines placed in pods under the wings. One major benefit of this is that it provides wing bending relief. When taking off or rising in altitude, the aircraft wings will often react by bending upwards. The engines and fuel add the necessary weight to counteract this reaction as well as resist potential damage as a result. In addition, having the engines below the wings allows for easier access and maintenance, though it also exposes them to greater risk of damage from objects on the ground.
Engines Are Attached to Pylons
The engine pods are not attached directly to the wing, but instead to pylons. Though designs for these components vary, pylons in general are rigid, metal structures that are fixed to the wing with a solid, secure fit. Aside from supporting the engines, the pylon creates some distance between the engine and the wing which is vital for a couple reasons. Firstly, by having the engine away from the fuselage and wings, there is more protection in the case of engine fire. Secondly, having this added distance and placement below the wings also creates a sound barrier so the nearby passengers endure less noise pollution.
Connecting the Engine Pods to the Pylons
Engine pods are usually connected to the pylons using heavy-duty bolts that are highly resistant to vibration along with other environmental factors. As such, the pods are generally connected at just two points–the top of the fan frame and the turbine frame. These connections are designed to take the massive force of the engine, both from its thrust and weight. Moreover, the fastenings are designed to safely support the maximum force experienced, but not take too much force. As such, the bolts are built incredibly strong, enough to support forces in excess of the maximum expected forces, but are also designed to shear in the event of extreme forces. If the engine comes in contact with the ground, for example, the forces experienced would break the bolts and cause the engine to detach from the pylons. This is preferable to the engines remaining attached because they pose serious fire risk and could even break the wing.
Aircraft Pylon Noise Control Systems
Besides simply providing a structure to connect the engines to the wings, pylons can also be designed to aid in noise reduction. Modern pylons are designed in such a way that air passing through the pylon will actively disrupt the jet engine exhaust stream after it exits the engine. With the exhaust stream being the cause of a lot of engine noise, including an air intake in the pylon design greatly reduces noise overall. To improve overall efficiency, these pylons would consist of pipes, a pump or pressure regulator, and a plenum chamber. This system would work by injecting higher pressure and velocity air into the exhaust stream, minimizing its trajectory and wake.
The pods, pylons, and bolts that are used to secure the engines have all been designed with consideration to weight distribution, safety measures, and other factors to make for the best possible engine placement. For access to an ever-expanding inventory of NSN, FSC, and aircraft parts, Accelerating RFQs is here to assist you with all your parts procurement needs. We invite you to browse our inventory of available items on our website and submit a completed Request For Quote (RFQ) form to receive a competitive quote for your comparisons in just 15 minutes or less!