Historical Rationale for Design Restrictions on D6AC Steel in U.S. Aerospace Structures

https://media.defense.gov/2009/Mar/11/2000611930/780/780/0/041109-F-8732E-004.JPG / (U.S. Air force photo by Gary Emery.)

A Royal Australian Air Force F-111C aircraft at Nellis Air Force Base, NV (U.S. Air force photo by Gary Emery).

What is the reason behind D6AC steel being listed as a restricted material?

DSIAC received a technical inquiry requesting information regarding the field experience that caused D6AC steel to be listed as a restricted material in NAVAIR EC-434-000-003. Materials engineering subject matter experts at the Texas Research Institute Austin, Inc. performed literature searches using the DTIC R&E Gateway, open sources, and university libraries to determine that specifically, the F-111 failure of 22 December 1969 was the primary reason that resulted in D6AC steel becoming a restricted material. A response report was compiled and delivered to the inquirer.

Inquiry Completion Date: 
Monday, June 17, 2019