enginehistory.org

[rwahlgren]

From reading the articles in the members section about Allisons, Merlins, and I suppose all reciprocating aircraft engines in that era. The process of manufacturing and sending the units out the door is, assembly, testing, teardown, reassembly.

I have a question, is there a final run after final reassembly?
And how many total assembly hours are there?
To do a proper assembly with all the precision checks that need to be done, I would think the man hours would be pretty high. That sort of manufacturing practice would be very prohibitive nowadays. I don't think there is any large or small aircraft engine overhaul facilities that would ever consider doing that sort of procedure.
It would be interesting to know how many hours most shops would say it takes to completly assemble an R-2800.
Precision takes time. I read someplace that it takes 80 hours to assemble an F1 race engine.

[kmccutcheon]

Green runs were reduced in number after awhile with all engines being run at least once after assembly/reassembly. I suppose that for most of them they drained the oil, checked the screens, preserved them, packed them and shipped them.

Dan Whitney replies:
The details of the acceptance testing were hammered out in the contracts with each customer.
One of the outcomes of the production miracle that was WWII was the development of the science of Operational Analysis. Because of the large number of identical items being tested they were able to determine the point where the green run teardown was causing more problems than it was finding. I do not know of any "order" that obsoleted the green teardown, and I have no documents from Allison saying to end it. In fact they always continued the effort, but it was on the order of two randomly selected engines out of each 100. In Allison's case I believe that they stopped doing the 100% teardowns in 1942, but I have no documentation to prove it.
I would be interested if anyone does have any such documents.
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Kimble D. McCutcheon