i Pressure Test for Tanks. -Repaired tanks must pass the following internal pressure tests before being returned to service.
j. Damage Necessitating Replacement. - Cracking or perforation of the bag shell or tank due to corrosion, or damage which by its extent or location renders the success of the repair uncertain, necessitates replacement of the tank or shell. Damage beyond repair of the self-sealing bags due to fuel saturation should also be replaced. 2. Radiators. a. Coolant - P-40D P-40E P-40E-1. - The coolant radiators are constructed with a core frontal area of 1.11 square feet,a cooling surface area of 147 square feet and a free air area in the. core of .715 square foot having a minimum flow of 120 U.S. gallons (100 Imperial gallons) per minute with 7 -1/2 pounds per square inch inlet pressure and 0 pounds per square inch outlet pressure. b. Coolant - P-40F. - The coolant radiator is constructed with a core frontal area of 1.75 square feet, a cooling surface area of 383 square feet, having a flow of 200 U.S. gallons (166.6 Imperial gallons) per minute with 10 pounds per square inch inlet pressure and 0 pounds per square inch outlet pressure. c. oil-P-40D P-40E P-40E-1. - The oil cooler, United Aircraft product U-3385-DBS type "11" is constructed with a frontal area of 95 square inches and a cooling surface of 86 square feet and weighs 44.5 pounds. d. Oil - P-40F. - The oil cooler, United Aircraft product U-6507-D8 is constructed with a frontal area of 38.5 square inches and a cooling surface of 35.1 square feet and weighs 18.25 pounds. e. Construction. (1) Coolant Radiator. - The coolant radiator consists of copper tubes (.006 inch x .230 inch OD x 12 inches). |
The brass header bulkhead flanges are turned for attachment to the shell and riveted. All rivet heads or external surfaces are sealed with silver solder which is a lead base containing from 5 percent to 6 percent silver,developing a high shearing strength and having a melting point of 304° to 370°C (581° to 698°F). (2) Oil Cooler. -The inner and outer brass shells and the valve flange casting of the oil cooler are assembled by silver soldering. The core tubes are held together, one tube to all its adjacent tubes, and the core assembly complete to the shell by means of a lead tin solder. Tubes used are .210-inch diameter x .250-inch hex. f. Cleaning Before Repair. (1) Oil Cooler. - In all cases where any type of repair work is to be done the cooler must first be drained of oil and then thoroughly cleaned. Carbon tetrachloride or tricolor ethylene are the best solvents for cleaning oil coolers and should be used at elevated temperatures, approximately at the boiling points of the liquids. However, in the absence of any heating means, these solvents at room temperature will perform a satisfactory cleaning job. A 50-50 mixture of carbon tetrachloride and naphtha or a mixture of carbon tetrachloride and Sunoco spirits may be used if desired. The solvent should be mixed as required in quantities sufficient to meet daily requirements. It is recommended that the liquid be pumped through the cooler. A hand fuel pump, transfer pump, or a .power-driven pump may be used. The liquid should be strained as it leaves the cooler to catch any partic1es of hard carbon, metal, etc. If bearing metal particles are found, the cooler should be scrapped. The interior of the cooler, after cleaning should be flushed with hot running water and steamed for not less than 1/2 hour. The steam should pass downward into the internal passages with the regulator so placed that the condensate will drain freely from the bottom. (2) Coolant Radiators. - A solution consisting of 1 to2 pounds of concentrated soap to 40 gallons of water makes a satisfactory cleaning solvent. After thoroughly washing the radiator, remove the soap solution and flush the exterior and interior with clean hot running water. After rinsing, steam the interior of the radiator for not less than 1/2 hour. The steam should pass downward into the internal passages with the radiator so placed that the condensates will drain freely from the bottom. g. Testing for Leaks. (1) Oil Cooler. _ After cleaning as described above, locate leaks by submerging the cooler in clean warm water with all openings closed and an air pressure of not more than 75 pounds per square inch applied. The pressure is to be applied and released slowly to prevent any strain or shock. Then mark |
