I can't speak for all companies, or even all aerospace companies, but I can give you my experience. If I was on a project (aircraft prototype development), I could BILL overtime if authorized (and if I worked it of course); overtime was usually authorized. By contract with the DoD, if you worked the hour, you had to bill it. Off the project in the IRAD dept, I was able to bill overtime for one case, a 2 month long proposal writing. How much did I actually work? Always more than billed, even when overtime authorized and paid.
In my present position, I can bill as many hours as I want for the client I am working for, until the money runs out. Remaining work has to done on my time, that is, for free. So if a subcontractor stiffs me and delivers something 1 yr late (on a 2 yr contract), and I need the subcontractor's input to deliver the Contract Deliverables (primarily the final report), I have to work for free to finish the contract.
I would be interested in knowing: what's worse? a company demanding you work free overtime, or you walking away from the job before finishing because you refuse to work for free?