What do you want to do with it in your 28 volt plane?

Uh, air up the tires?

(It's generally a
stand-alone tool.)

??

You said you were looking for one that works with a 28 volt plane. My air
pump is a 12 volt contraption, and is a stand-alone unit. It doesn't matter
what voltage your plane is, when all you want to do is fill up your tires!
:-)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"