This specification covers the requirements for two types (see 1.2.1) and two classes (see 1.2.2) of low volatile organic compound (VOC) content (see 3.4.2), solvent-borne, elastomeric, polyurethane primer coatings. These primer coatings are formulated primarily for spray application, are compatible with polyurethane topcoats, and are intended for use on aircraft and other equipment subjected to structural flexing at low temperatures. The maximum volatile organic compound (VOC) content of the admixed primer coatings is 340 grams per liter (g/l) or 2.8 pounds per gallon (lbs/gal). Unless a specific type and/or class is referenced in the contract or purchase order, TT-P-2760A, Type I, Class C is the default. Class N may not be substituted for Class C, unless authorization for its use is given by the procuring activity or engineering authority for the system or item to which the primer coating is to be applied. See 6.13 for the cross-reference of classes to previous revisions of this specification.