How Are Engines Attached to Aircraft?

The majority of large commercial aircraft feature two or four engines mounted in pods underneath the aircraft wings. However, securely attaching these engines onto an airplane wing requires a complex process and is not as simple as tightly bolting them onto the apparatus due to strict safety precautions. To learn more about how aircraft engines are fixed onto their wings, we encourage you to read on.

Where Are the Engines Housed?

Positioning commercial aircraft engines inside pods underneath the wings has several advantages. To start, doing so provides aircraft wings bending relief because the weight of fueled-up engines counteracts the effect of lift, bending the wingtips upward. This makes it easier to access and maintain the engines, but the engines are at a greater risk of foreign object damage. To prevent wing fluttering and reduce the weight of the structure, aircraft engines tend to be mounted slightly forward of the wing.

The Purpose of Pylons

The engines in pods are attached to a pylon, rather than directly to the wing; the pylon is securely fixed onto the structure of the wing. The pylon is important because it creates distance between the engine and wing in case of an engine fire so that the wing is protected until the fire can be extinguished.

How Does the Engine Pod Attach to the Pylon?

Bolts are used to connect the pylons to the wings, and the pods tend to be connected at two points: the top of the fan frame and the top of the turbine frame. These connections are built to withstand the massive forces of the engine, including the forward thrust and downward force of the engine weight. It is crucial for these bolts to support the maximum forces experienced while avoiding excessive force. Though bolts are able to support forces significantly in excess of maximum expected forces, hard landings or extreme turbulence will cause shearing. For example, if the engines come into contact with the ground, the bolts will break, causing the engines to detach from the pylons which prevents possible fires.

Why Are the Wing and Engine Separate?

Commercial jets do not have engines incorporated into the wings themselves for a few reasons. First, this presents a safety issue because if an engine fire were to erupt within a wing, the results could be significantly more devastating than if the engine was podded. Ideally in this situation, the fire can be extinguished in the pods before it causes any significant wing damage. Additionally, placing the engines in the wing takes up much needed fuel tank space. Lastly, since turbofan engines are continually improving their technology and growing in size, they would fail to fit inside the structure of a wing.

Pylon-Related Crashes and How They Can Be Prevented

There have been two major pylon-related crashes in the twentieth century caused by insufficient inspections and oversight of major issues prior to flight. For example, an American Airlines flight crashed shortly after takeoff in 1979 following the detachment of its number one engine. The engine and its pylon accessory separated, causing a meter-long section of the leading edge to break away; this led to the components rolling over the top of the wing prior to landing behind the plane on the runway. It was later determined that the pylon assembly experienced damage during routine maintenance about two months prior. To save time, the engineers working on the aircraft removed the engine and pylon from the wing as a single unit. This crash could have been prevented if the engineers had removed each component separately, as intended.

In 1992, another pylon-related crash occurred; shortly after departing, the aircraft climbed 6,500 feet before its number 3 engine and corresponding pylon became separated from the wing. It fell out and backward, colliding with the number four engine, before that engine and its pylon detached as well. The crash was investigated, and it was discovered that there were fatigue cracks that had developed on the fuse pins which were meant to keep the pylons in place. Performing proper inspections preflight has the potential to save lives and maintain flight safety, making it absolutely essential.

Where Can You Find Quality Engine Parts?

Those in the market for aircraft engines and their components are encouraged to work with Alpha NSN, a leading distributor of high-quality parts you are searching for. With AS9120B, ISO 9001:2015, and FAA AC 00-56B accreditation, you can rely on the caliber of our offerings. We have more than 2 billion new, used, obsolete, and hard-to-find parts available for your immediate purchase, many of which are subject to rigorous quality control measures. Those with time restrictions can count on us to expedite shipping times for both domestic and international customers, as we have a supply network that stretches across the United States, Canada, and the United Kingdom. Fill out an RFQ form to commence the parts procurement process with a partner you can trust.

1. kevin jeff
2. Posted on December 20, 2022
aircraft parts

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