Theres probably a hell of a lot more to it than whoever is looking at this is asking. Unless hes a physical science forensics blah blah what have you expert, he realy shouldn't be asking these questions. One thing I could name off, is that the wings of any aircraft are extremely light and extremely frail. Its very unlikely that they would do much dammage to the building, in fact, when the foremost part of the wing hits, it would shear the things back so they can't do any horizontal dammage much beyond that of what the fuselage would do. If you go look at the WTC post impact, pre collapse shots, you will probably notice the same, but not only that, IIRC the pentagon was actualy built out of a much more durable cement material in defense of a possible attack.
IMO this is the same bullshit as the people who denie that the US government ever went to the moon. These people think the government is out to get them, they wear metal helmets, and they lock their food inside of a safe which is locked inside of a refridgerator that has double dead bolt, because they are afraid that "they" are going to poison them for letting out their "secrets" like this.