I think it would be cool if when your plane was shot and the wings leaked fuel, you could see a small effect, like fuel actually leaking. Another thing would be if a fuselage has buoyancy and gets damaged by a torpedo or gun, it will lose buoyancy and sink. Maybe jet engines could overheat if run on max for too long, and would shut off.
Just as a side suggestion, it would be cool is there was an engine starter switch that would make your engines spool up instead of constantly being ready to go. Like how in real life, starting the rotors on a huey takes like 2 mins, whereas in SP it takes 5 seconds.
I wouldn’t want engines to randomly shut off, or have the plane take 2 minutes to take off. But I like The gas leak idea.
And buoyancy do lose a bit of their buoyancy when damaged, for the fuel leaking thing i don't think it will drip fuel as all bullet (except cannon) in SP were Tracer-Incendiary as it will catch fuel tank on fire, the tracer itself can already light aircraft on fire, on the incendiary it will also burn planes (both IRL)
We have it in SR2 but SR2 succ for planes in my opinion due to its control were made for rocket and not planes
If something gets hit with a torpedo, that thing is going to explode. Torpedoes often carry an explosive charge equivalent to more than half a metric ton of dynamite and explosives are even more powerful underwater than above. Large vessels have been torn in half by a single torpedo hit.