Originally posted by wtlwdwgn Actually, that isn't just an old B727, it's the oldest B727, as it's the very first B727.
Well, the first one sold to a customer.
The first few planes are used for testing and proof of concept. Like the one that went straight to the structural stress test7ng where they bend the wings up and down repeatedly until failure, and alternately pressurize and depressurize the fuselage to ensure the structural integrity of the airframe. Another plane is used for flight testing and development of design adjustments.