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I just noticed yesterday that the right and left forward doors of all E-Jet Family aircraft have different sizes (both in height and in width). What is the reason behind this design difference?

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It's actually more common than one might expect, and not just in the E-jet family.

The de-facto standard is that passengers board from the left and the right side doors are only used to load logistical stuff (ie catering) during the turnaround or during an emergency evacuation.

As such, the left side door(s) must fit certain FAA standards (so it fits jet bridges or the average human height, for example).

For example, on the Boeing 737 (all models), the left forward door is 0.86 x 1.83 meters while the right forward door is 0.76 x 1.65 meters, 20 percent smaller (by area).

Now you might ask "ok, so make both doors the size of the left door". It's beneficial, from engineering/structural point-of-view, to have each door as small as possible.

(http://www.boeing.com/assets/pdf/commercial/airports/acaps/737.pdf pages 73 and 77)

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  • $\begingroup$ What benefits exist from engineering/structural point-of-view, to have each door as small as possible exactly? Just curious... $\endgroup$
    – Ja380
    May 15 '20 at 21:28
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    $\begingroup$ @Ja380 pressurization/structural integrity concerns. $\endgroup$
    – DeepSpace
    May 15 '20 at 21:44
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    $\begingroup$ You have two big holes in a pressure vessel at the same station. To get away with doing that, the frames around the openings have to be reinforced, often with the doors themselves carrying some of the tension loads through the latching system's interconnection with the frame. The smaller the opening the better, from a strength to weight perspective, so the SD is made to be as small as practical. $\endgroup$
    – John K
    May 16 '20 at 0:59

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