Mid year 273 in 64 Darts?
You were in production in a average year, how few ahead of release date did the casting and machining start? I can imagine design and engineering started at least a year prior.
Back then, I believe it was about a 3 1/2 - 4 year cycle time from start of design to production... Now days, they try to cut it down to 2 1/2, which I think is not enough time if there are any hiccups...
They can't start the castings until they get a design freeze and they have a 'target' to shoot for... They keep tweaking designs for various reasons in the design stage... Once you get everything in the design, then you can start making the tooling to produce it...
Since it would have been a new program, they wouldn't have to worry about taking the production tooling down to run the trials... They can start the tooling as soon as the design is determined...
There are two stages of tooling: Prototype (soft) tooling, and Production (hard) tooling...
Prototype tooling is quicker and cheaper to make in the early stages of the program so you can get parts to test with, but the tooling is not as hard as the production tooling and wears out faster... Soft tooling has a limited capability of how many parts you can make with them before the tools wear out...
Then the production tooling is more expensive and permanent (harder) so it last longer... However it takes longer to make....
As an engineer, you do your Design Validation testing with prototype soft tooled parts to prove out that the design works and will last through it's life cycle testing...
Once the design is done and your part has passed all of the design validation testing, then you kick off the production tool... You must run test parts off of the production tool before you send any out to customers... This is your production validation testing to make sure that everything is ok with the production tooling and the parts it makes...
Then you have the machine stage... Each machine for each station on the block machine line and the engine assembly line are built by outside machine building shops... They don't have one company do the whole line as that can get overwhelming... They split it up between a few different machine builders because when the machines are launched, they will have people at the plants to support the launch...
Each machine for every station for the machine line and assembly line must be test run before it ships into the engine plant... So they will need a batch of parts to run on those machines to make sure they work properly... If parts from the production hard tool are not available at this time, they will use soft tooled prototype parts for the run off at the supplier's place...
After the machine is 'run off' on the supplier's building, then it is shipped and set up at the engine plant and then it has to be run/tested after it's installed... This is where it is important to have production tooled parts to tun the machines in... There will be some slight differences between the soft tooled prototype part and the hard tooled production part, so you want to tune and adjust the machines to the production tooled parts...
It's hard to put a particular time frame on it as it depends on each program and how far ahead or behind schedule it is... They try to get the longer lead time parts kicked off as early as possible to try to keep them from delaying the launch...
