These might be dumb questions, but as I go through the regulations concerning private and commercial privileges I'm trying to challenge myself to make sure I have a decent grasp of the material. Here are two situations: 1) Private pilot is working at a flight school and earning $10/hr. Owner asks him (while he's on the clock), to move a plane to another airport for scheduled maintenance. I believe there is a letter or interpretation out there that states that even "free flight time" counts as economic benefit and thus would be considered payment and in need of a commercial certificate? Not sure where the line is drawn here. Which brings me to: 2) Private pilot has a friend who just throws him the keys to his plane and say, "I don't get to fly that often and don't want the thing rusting into the ground, it'll be good to get the oil flowing". You're now technically getting free flight time (economic benefit/compensation), does it require a commercial certificate?