[ItBites]

Al and others: I get the point about this application might not need to be particularly accurate. You may be correct. I'll top that by suggesting that AC would have been unlikely to specify anything other than 'mild steel' and probably got materials over the years from various suppliers , which would make determining authenticity by comparing to sibling materials very dicey, even with the highest accuracy equipment and techniques.

Also, since you brought it up, most GSE is not even allowed to be built to industry practices due to the sensitivity of lifting, handling, interfacing, or pressurizing one-of-a-kind, high-value hardware. the downside of a COTS GSE component failure is just too catastrophic in terms of human and financial loss (think of dropping a large rocket motor). There are some exceptions to this of course, but most GSE just defaults to being Mil Spec compliant. You have no idea what it takes to get NASA (and customers in general), the Ranges (who let us integrate on their proerty and let us fly out), the FAA(who controls the airspace), the DOT (who allows us to ship over the nations hiways), DCMA (who lets me handle and test ordnance), the DOD, and a myriad of others who poke their noses in my business to all agree that things are kosher. Most times it is just best to be able to point to a Mil Spec in order to stop the incessant do-loops that cost even more to navigate than complying with Mil Specs. Commercial Programs may be a target of opportunity for industry common practices and are assessed on a case-by-case basis, but that doesn't fly at all on DOD Programs, even for GSE.