I’m running a Nightwitches campaign, situated in real WWII. I’m currently using a lot of the environmental soundsets, and weapon sets, but so far I don’t have any good way to represent planes in flight (I’m cheating by using the motor from the 1920s carchase and howling wind) or WWII dogfighting.
Similarly, a soundset for mechanics working on weapons and planes would be very nice.
While I can’t help with the aviation noises, the Sci-Fi player’s Spacedock set has work tools, machinery, and welding sparks elements that might work for working on planes. Even the com voices element might work for muffled announcements over a PA in a hangar.
The Alien Laboratory set has the elements tools of the trade and more tools, which sound like someone using metal tools or rummaging around in a toolbox, which might also be useful for you.
Strangely enough someone suggested Bi-Planes and propellor craft at PaxUnplugged so it’s inspired me! I’ll have a look and see what we can do 
Coolest cheat ever! 
I also wouldn’t say nay to some modern jet and/or airliner sounds, for when you want to recreate “Terror at 30,000 ft.” for your game… 
For totally selfish reasons I was thinking about making a soundset with planes taking of and a little ATC background voices…
Maybe @Steve can make some recordings today, while going home.
I’ll see what I can do, looks like I’ll be at the airport for a while so that should keep me out of mischief 