compressor (GTC) used to provide air and electricalpower for starting aircraft jet engines. The start unitcontains all the components and fuel supply necessaryfor independent operation. The start unit requiresmanual start initiation/stop and manual air selection.Once started, an engine control system regulates start,acceleration, and engine operation. Air start hoses andelectrical cables are provided. This unit is used aboardshore stations.A/S47A-1 Jet Aircraft Start UnitThe A/S47A-1 jet aircraft start unit (fig. 9-20) is atractor-mounted, self-contained, mobile aircraft turbineengine air start unit. The air start unit enclosure consistsof a control panel, enclosure assembly, gas turbine aircompressor (GTC), stowage rack for the air start hose,and turbine support and mounting assembly. Except forfuel and electrical power (supplied by the tractor), theenclosure contains all systems necessary for gas turbineengine operation. This unit is used aboard ship and onshore stations.WARNINGHot exhaust from a jet aircraft start unit is aserious hazard when operating in close proximityto aircraft, aircraft components, fuel, weapons,equipment, and personnel.You must take extra special precautions as to wherea gas turbine compressor (GTC) is positioned duringoperation, especially aboard ship where aircraft areparked closely together. High volume air pressure,extreme exhaust temperatures, jet intake suction, highnoise levels, and unqualified operator's are all potentialhazards.A/M27T-5 Hydraulic Portable Power SupplyThe A/M27T-5 hydraulic portable power supply(fig. 9-21) is a self-contained, single-system, hydraulicpumping unit powered by a three-cylinder, two-cycle,diesel engine with a rated capacity of 20 gpm at 3,000psi and 10 gpm at 5,000 psi. During normal operationthe diesel engine runs at speeds up to 2,500 rpm. TheA/M27T-5 engine operates on JP-5 (jet fuel) or dieselfuel, and the hydraulic reservoir holds 20 gallons.Pressure and return hydraulic hoses, a tow bar, tie-downrings, and a manual hand brake are provided.A/M27T-7 Hydraulic Portable Power SupplyThe A/M27T-7 hydraulic portable power supply(fig. 9-22) is similar in operation to the A/M27T-5except for its source of power. The A/M27T-7 ispowered by a 50 horsepower electric motor. A 50-footpower cable is provided for connection to an external440-volt, 3-phase, 60-hertz power source and can be setup to operate on a 220-volt source. The hydraulicreservoir holds 16 gallons and is equipped with a fluidlevel sight gauge. Pressure and return hydraulic hoses, atow bar, tie-down rings, and a manual hand brake areprovided.9-12ANF0920Figure 9-20.—A/S47A-1 tractor-mounted jet aircraft start unit.
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