26.31—Definitions.
         For purposes of this subpart—
    
    
        
        (a) 
        
            Fleet Average Flammability Exposure has the meaning defined in Appendix N of  part 25 of this chapter.
    
    
        
        (b) 
        
            Normally Emptied means a fuel tank other than a Main Fuel Tank. Main Fuel Tank is defined in  14 CFR 25.981(b).