FAA SAIB for crashworthy fuel tanks
The FAA has published an SAIB with a link to a list of approved crashworthy fuel system designs.
https://rgl.faa.gov/Regulatory_and_Guidance_Library/rgSAIB.nsf/0/8997c0a7f5f7a5a6862584c70076cefa/$FILE/SW-17-31R2.pdf