35

There are 2 main reasons: The wing spars run through that area. If you wanted to keep the wing spar within the oval cross-section, you'd have to install the wing much higher on the fuselage which means the wing spar goes through the passenger cabin. Behind the wing spars, the landing gear is stored. The flat bottom provides more internal space. Another ...


21

Two reasons: Airplanes are not completely, perfectly hermetically sealed. They are pressurized using positive air pressure from the engine bleed air and packs. If there is a failure in the system, the aircraft internal pressure will return to the outside ambient pressure. Air will escape the aircraft or enter the aircraft if the outside ambient pressure is ...


21

In general, those are called blade antennas. They consist of a monopole antenna (a single rod sticking out of the fuselage) with an aerodynamic fairing around it.


17

It looks like a VHF and ELT antenna. References: Boeing 737NG Radio Equipment Communications


16

USAir 1549 flooded because the doors opened. Passengers attempted to open the rear doors, worsening the problem. Airplanes are not sealed at all. Not remotely close. They're not air-tight. Pressurization is maintained by varying the air outlet, called the outflow valve. A large volume of air is constantly being pushed into the cabin via the engine bleed ...


14

Hobbes' reply has some of the main reasons, but there's some more: That flat bit is called the "belly fairing", and its functions are: Avoid some aerodynamically awkward corners that would happen if the wing profile just went straight through the fuselage, with no rounded corners etc. at the intersection. This is particularly useful at the wing ...


14

There was a hole in the fuselage, and cargo doors had come open. And someone had opened a rear door that couldn't be closed.


5

Yes it's the apu exhaust ... there is a post about it: Where is the inlet for the APU on a Fokker 70/100?


3

You really only have two options; stretch or swell. The Q400 already has a "combi" configuration option with 50 seats forward and a cargo hold taking up the aft third of the cabin, so if you want to just add another couple of plugs, one (smaller plug) forward of the wings and one aft, to get 74 seats plus a large cargo area, you can do that and ...


1

It may not be possible to provide a precise number for a question with so many variables. Likely, the amount differed between variants. Without speaking to a materials acquisitions director from Boeing in the 70s and 80s, the precise number is probably not available. That said, this airplane scrapyard website mentions that aluminum accounts for approximately ...


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