on the aircraft. There are several barrier materials available in the Navy stock for sealing and shrouding large aircraft openings. The stock numbers for these materials can be found in NAVAIR 01-1A-509. Water-vaporproof Barrier Material. This material is a laminated metal foil barrier that has good water-vapor resistance. It is used for closing intake openings, protecting acrylics during cleaning, and for the packaging of removed components and accessories that are returned for overhaul. It is heat sealable with a soldering or clothes iron. Polyethylene Plastic Film. This barrier material is used for the same purpose as the metal foil barrier material, but it is less expensive. However, it is not puncture resistant. This plastic film is heat sealable only with special equipment. Polyethylene Coating Cloth. This cloth is used in support equipment covers. Its use is preferred over plastic film material for general shrouding because of its greater tear and puncture resistance. Tape, Federal Specification PPPT-60, Class 1. This pressure-sensitive tape is used to close small aircraft openings and for direct contact use on noncritical metallic surfaces. It has moderate water-vapor resistance that is adequate for maintenance use. Pressure-sensitive Adhesive Tape. This tape was developed specifically for exterior preservation and sealing. It can be applied at temperatures as low as 0°F. It should perform satisfactorily over a temperature range of -65°F to +140°F. It is an excellent general-purpose tape for exterior preservation and sealing operations. Q36. Q37. Q38. Q39. Q40. Q41. State the levels and terms of preservation used for naval aircraft. What level of preservation is required if an aircraft is scheduled to remain idle for more than 14 days but less than 28 days? MIL-C-16173, corrosion preventive compound, is available in three grades. Which grade(s) is/are easily removed with dry-cleaning solvent? Corrosion-preventive petroleum, class 3, provides protection for what type of surfaces? When is general-purpose lubrication oil VV-L-800 used? What type of corrosion-preventive compound MIL-C-81309 is used on avionics and electrical equipment? ENGINE PRESERVATION NAVAIR 15-01-500, Preservation of Naval Aircraft, addresses specific requirements for the cleaning, inspection, protection, maintenance, and depreservation of auxiliary power units, gas turbine engines, and reciprocating engines. This section only highlights some important factors in engine preservation. Refer to the Preservation Manual for specific details. Level I preservation of engines requires the fuel system to remain at least 95% full of fuel for a period not to exceed 60 days. Any fuel system that has been drained of fuel for more than 3 days or is expected to remain inactive for more than 60 days is to be preserved with MIL-L-6081 Grade 1010. and be dehumidified. Level II and III preservation requirements are also outlined in the Preservation Manual. All requirements are listed by type engine and level of preservation desired. NOTE: In any case of preservation, ensure all logbook entries and preservation tag requirements have been met. SUPPORT EQUIPMENT PRESERVATION WARNING Do NOT use oil-based preservatives around oxygen fittings or oxygen regulators since fire or explosion may result. The preservation of clean, corrosion-free surfaces is the final step of the preventive maintenance process of SE. The act of preservation helps to protect nonmoving parts by filling air spaces, displacing water, and providing a barrier to corrosion. Preservatives For SE Preservatives are used after SE cleaning before ocean assignment when an extended period of SE storage is anticipated. Preservatives are also used wherever paint films require additional preservative (for example, in metal joints, tightly fitting surfaces, and on sump areas). The technical corrosion manual to be used for support equipment is Ground Support Equipment Cleaning And Corrosion Control, 4-18