Registration Numbers

[SmallCar]

I was going to fill out the FAA paperwork to obtain an "N Number" for my Double Eagle but I stumbled over the spot that wants me to list the engine number.  I don't have an engine yet.  Do I have to have an engine number to obtain the registration number?

[okdonn]

You can reserve a registration number without any aircraft information, then use it when you get the inspection.

[SmallCar]

Thank you for the info!