What Are Aircraft Plug Doors?

When passengers board planes, they are generally entering a specialized door known as a plug door. Unlike the doors used for cargo compartments or other aircraft sections, the plug door is specifically designed to be self-sealing, relying on the use of differential pressure to remain shut. What this means is that the higher an aircraft ascends, the more pressure there will be against the plug door. As a result, it is nearly impossible for an individual to force the door open mid-flight, ensuring safety of all.

As one may know, a majority of passenger-oriented aircraft feature sealed cabins, allowing for air pressure and temperatures to be controlled for the comfort and health of all on board. As the pressure within the cabin differs from that in the surrounding atmosphere, a differential pressure is formed where outside pressure is greater inside of the aircraft than outside.

While traditional doors found in buildings and other spaces may rely on locking mechanisms such as latches or bolts that are engaged to remain shut, plug doors are devoid of any such features. Instead, they are designed to be wedge-shaped where the widest part of the door faces the inside of the cabin. The frame of the aircraft accommodates this shape, so the door will nestle into the opening when shut.

The wedge-like shape of the plug door is essential for its ability to remain shut, as the greater pressure inside of the cabin will exert a large amount of force on the door, keeping it wedged into the airframe opening. This makes it so that there is no need for a latch or bolt to keep everything secure, as the door will only open once the aircraft is at a low enough altitude where pressures on each side of the door are more equal. While this safety feature is essential for preventing passengers from forcing the door open for whatever reason, it also helps maintain the seal of the aircraft so that the internal atmosphere can be more optimally governed.

While plug doors are extremely common to passenger aircraft, they are also quite popular in other similar applications as well. For example, plug doors also find use on spacecraft, those of which rely on the sealing capabilities of the door for very similar reasons. These plug doors have been found on several Apollo spacecraft. While aircraft utilize plug doors that are wedge-shaped, spacecraft will feature hatch-shaped plug doors. While performing the same role, the difference in shape comes down to the particular operations of the vehicle and how entering and exiting it is conducted.

While plug doors are essential for sealing the cabin of a passenger aircraft, so too are other various sealing products like window seals, hatch seals, and other such products. If you find yourself in need of various aircraft parts and components that you require for carrying out operations, there is no better source than ASAP Aerospace for all your various needs and requirements. On our website, we provide customers access to over 2 billion new, used, obsolete, and hard-to-find parts that have been sourced from leading manufacturers that we trust. As all items are ready for purchase at any time, we encourage you to fill out and submit an RFQ form at your earliest convenience to begin the purchasing process.

With our peerless dedication to quality control and export compliance, we proudly conduct operations with AS9120B, ISO 9001:2015, and FAA AC 00-56B accreditation. Furthermore, with our strict NO CHINA SOURCING pledge, all purchased items ship out alongside any applicable qualifying certifications or manufacturing trace documentation. See how we can serve your various needs today when you get in touch with one of our industry experts through phone or email. 

1. jacob luiz
2. Posted on November 3, 2022
aviation