Unit Specific 202
The following system components and component parts are discussed below mentioning their function, location, and safety/protective devices.
Power section- consists of an axial-flow
compressor, a combustion chamber, a multi-stage turbine, and an
exhaust section. The last two stages of the turbine are used to drive
the propeller using the torquemeter assembly and the reduction gear assembly.
202.1.2 Propeller blades
The four-bladed Hamilton Standard (54H60-77) propeller provides an efficient and flexible means of converging engine SHP to thrust. The propeller consists of two principal sections: the rotating section comprises the blades, hub, spinner, and the dome that houses the pitch changing mechanism; the nonrotating section contains an oil reservoir, pressure and scavenge pumps, the governor, and control mechanism. It is a constant-speed, variable-pitch, full-feathering propeller, having the added features of negative torque sensing, pitchlock (to prevent excessive overspeed), and a combination synchronizing and synchrophasing system. The explaination of the propeller nomenclature is listed below:
5(mod #)4(#blades)H(shank size/type)60(spline size)77(minor mod#)
202.1.3 Auxiliary Power Unit
The APU is what makes the P-3 a self-sustaining aircraft. The APU is made up of a turbine compressor driving a generator that is identical to the engine-driven generators. The gas turbine compressor has a two-stage centrifugal compressor and a single-stage inward flow radial turbine. Air bled from the compressor is used for engine starting, ground air-conditioning, or for bomb bay heating. Because the power developed by the APU is somewhat limited, all of the features cannot be used simultaneously. If bleed air is demanded in sufficient quantities to jeopardize the generator output, the amount of bleed air being delivered is automatically reduced. Ground air-conditioning and engine-starting air cannot be used simultaneously. It is possible, and permissible, to use ground air and bomb bay heating simultaneously. The APU can be operated in flight for electrical power use, but bleed air is not available.
On some aircraft the GTCP 95-3 APU is installed that produces an increased airflow from the GTC 95-2 model. Though both models are interchangeable, they do not have the same EGT limitations.
202.1.4 Fuel system:
Fuel cells- four integral wing tanks and an
auxiliary tank carry the fuel supply for the engines. The auxiliary
tank, identified as tank No. 5, consists of a bladder-type fuselage
tank connected to an integral center-section tank. The bladder cell
is located in the unpressurized area of the lower fuselage forward of
the integral tank. All tanks are automatically protected against
excessive positive and negative pressure during fueling, transfer,
202.2.1 How do the following components work together to achieve the systems function:
Power section- consists of a 14-stage,
axial-flow compressor; six cylindrical combustion liners that
comprise the combustion section; a 4-stage turbine section; an
accessory drive unit; an oil system; and a fuel control unit.
202.3.1 What is the P-3C total fuel capacity in U.S. gallons?
9,200 gallons total
JP-4 = 59,800 lbs. @ 6.5
JP-5 = 62,560 lbs. @ 6.8
JP-8 = 61,640 lbs. @ 6.7
202.4.1 How does the ambient air temperature influence the operation of the Fuel system?
Fuel quantity indication can vary even though the aircraft is serviced with the same number of gallons of fuel. The factors that cause the fuel weight to change with a constant quantity are temperature and fuel density tolerances. Fuel production specifications for JP-4 and JP-5 permit a density range of ± 0.2 pounds per U.S. gallon. JP-8 fuel specifications allow a density range of ± 0.25 pounds per U.S. gallon.
For example, although JP-4 has a nominal fuel density of 6.5 pounds per U.S. gallon at 15° C, the same fuel at a temperature of 40° C has a density of 6.15 pounds per U.S. gallon. For an aircraft with 9,200 gallons of fuel, the load would be 56,580 pounds as compared with 58,510 pounds for nominal JP-4 at the same temperature.
202.4.2 How does the Fuel System interface with the following:
Propulsion system- each of the four wing tanks
can supply fuel to its respective engine or fuel can be supplied from
any tank to any engine through a crossfeed system.
202.5.1 What safety precautions must be observed during fueling operations?
Any RF transmission is a potential source of fuel
ignition. Use of transmitting equipment during fueling operations
should be avoided.
To prevent structural damage, verify positive fuel tank venting and ensure that fueling pressure does not exceed 55 psi. The pressure gauge for tank No. 5 must be closely monitored during fueling to prevent tank over-pressurization.
Because of wing dihedral, the filler wells must be located near the high outboard end of the engine feed tanks. Consequently, dipsticking through the filler wells will yield a no-reading indication unless the inboard tanks contain 4,225 pounds (650 gallons) of fuel or more, and the outboard tanks contain 8,775 pounds (1,350 gallons) of fuel or more.