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In the movie Top Gun 2, the main character Over-Gs his aircraft (I think, an F/A-18 Hornet to around 10G).

  • From a maintenance perspective, what steps have to be additionally performed in order to get this aircraft back in the air?
  • What is the absolute limit at which the aircraft is permanently damaged?
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A single overstress event is benign if you didn't permanently bend anything. That is, if the structure stayed within its elastic limits (like a spring), it's fine.

The inspection will be to look for permanent deformation from exceeding yield limits, and cracks or failures from exceeding ultimate limit loads (maybe where something failed, but there was a secondary load path in the design, so the plane didn't come apart).

In the end the absolute limit is the one that exceeds the yield stress limit for the first structural part to get there. Say, for a fighter, 8g yield (permanent bending) and 12g ultimate (wing spar or something breaks off).

There may be a published load limit, but there are fudge factors and a lot of variables, so you may have a 8g limit (maneuvering "red line"), but in a real event it may take 10 or 12 g to actually bend something permanently, and maybe 15g to get the wing to fold up.

When a commercial airliner gets overstressed, it gets a structural inspection, and if nothing is bent or broken, it's good to go.

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  • $\begingroup$ Do you know how the procedure is for military aircrafts? Because I remember some crew chief saying that overstressing a military fighter jet requires some maintenance afterwards. However I think he did not mention if that is pure inspection or also the swapping of some components $\endgroup$
    – U_flow
    Dec 20, 2022 at 16:06
  • $\begingroup$ Oh hard to say. I would guess "maintenance" just means inspection, but in the military they may use more conservative assumptions in view of the extreme operating environment, and say, replace things like bolts in critical areas as a matter of course. $\endgroup$
    – John K
    Dec 20, 2022 at 17:21

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