Unit Specific 201
The following system components and component parts are discussed below mentioning their function, location, modes of operation or control, safety/protective devices, protection, probable indications of failures, and interlocks.
Forward section- includes the flight station.
- Midbody section- the midsection of the aircraft.
- Aft fuselage section- includes the tail cone.
Center section- built as an integral part of the fuselage. It consists of a box-type beam which is an assembly of the front and rear spars, top and bottom skin panels, and ribs. The spar is 130 inches, from BL65L to BL65R. After the structure assembly is completed, the box beam is sealed to form an auxiliary fuel tank.
- Left wing outer panel- outer wing consists of wing flaps, leading and trailing edges, wingtips, ailerons, and engine nacelles.
- Right wing outer panel- outer wing consists of wing flaps, leading and trailing edges, wingtips, ailerons, and engine nacelles.
Horizontal stabilizers- provides stability of the aircraft about the lateral axis. This is "longitudinal stability." It usually serves as the base to which the elevators are attached.
- Vertical stabilizers- maintains the stability of the aircraft about its vertical axis. This is known as "directional stability." It usually serves as the base to which the rudder is attached.
201.1.4 Flight controls/surfaces:
Flaps- the wing flaps are of the high-lift Fowler type. This type of flap uses a combination of aft movement to increase the wing area, and a drooping (downward) movement to change the airfoil section. The wing flaps are powered by the combined No. 1 and No. 2 hydraulic systems. Because of this dual system operation, no emergency method of flap operation is necessary or provided. Each hydraulic system by itself is capable of supplying sufficient power for flap operation.
- Ailerons- are operated by a lateral (side-to-side) movement of the control stick or a turning motion of the wheel on the yoke. The ailerons are interconnected in the control system and work simultaneously, but in opposite directions to one another. As one aileron moves downward to increase lift on its side of the fuselage, the aileron on the opposite side of the fuselage moves upward to decrease lift. This opposing actions allows more lift to be produced by the wing on one side of the fuselage than on the other side. This results in a controlled movement or roll because of unequal forces on the wings.
- Rudder- used to move the aircraft about the vertical axis. If the pilots moves the rudder to the right, the aircraft turns to the right; if the rudder is moved to the left, the aircraft turns to the left. The pilot moves the rudder to the right by pushing the right rudder pedal, and to the left by pushing the left rudder pedal.
- Elevators- the operation of the elevator control system is initiated when the control stick is moved fore and aft. Raising the elevators causes the aircraft to climb. Lowering the elevators causes it to dive or descend.
- Trim tabs- small airfoils recessed in the trailing edge of a primary control surface. Their purpose is to enable the pilot to neutralize any unbalanced condition that might exist during flight, without exerting any pressure on the control stick or rudder pedals. Each trim tab is hinged to its parent control surface, but is operated independently by a separate control.
201.1.5 Landing gear
Strut- absorbs the shock that otherwise would be sustained by the airframe structure during takeoff, taxiiing, and landing. The air-oil shock strut is used on all Navy aircraft. This type of strut is composed essentially of two telescoping cylinders filled with hydraulic fluid and compressed air or nitrogen.
- Brakes- the engine-propeller combination on the P-3 aircraft is usually effective in stopping the aircraft and reducing the work brakes normally do. Four multiple-disc brake assemblies, one for each main gear wheel, are mounted on the strut side of each main gear axle. Brake clearance is adjusted automatically.
- Wheels- are made from either aluminum or magnesium alloys. The wheels on naval aircraft are of two general types- divided and demountable flange. Each landing gear on the P-3 consists of dual wheels and forward-retracting struts. The tires are 36 ply.
Pumps- there is three electrically driven, variable displacement type hydraulic pumps. Each pump has a maximum usable output of 8 gpm; 2 gpm are tapped off the pump and used for motor cooling. A low-pressure warning is initiated when pump output falls to 1,800 psi.
- Reservoirs- the two hydraulic systems have individual reservoirs, in accordance with the design aim of having isolated and independent systems. The No. 1 reservoir contains a maximum of 5.6 U.S. Gallons with an emplty brake accumulator or 5 gallons with a fully charged accumulator; the reservoir must be refilled if the level falls 0.8 gallons. The No. 2 reservoir is full at 1 gallon, and must be serviced if the level falls one quart (to 3/4 gallons).
- Booster assemblies- hydraulic flight control boosters operated by both hydraulic systems are incorporated in each of the three surface control systems. The booster system is designed so that the pilot has a normal feel of control forces when hydraulic pressure is available to the booster cylinders. Without hydraulic pressure, the controls can be moved but considerable force is required unless the booster shift handles are pulled.
- Actuators- a unit that transforms hydraulic fluid pressure into mechanical force, which performs work (moving some mechanism). Two types of actuating units are used in naval aircraft- actuating cylinders and hydraulic motors.
201.1.7 Airframe components:
Forward radome- a conical-shaped fiberglass structure weighing approximately 150 pounds. The shell is riveted to a channel-shaped former, which provides structural rigidity and serves as a support for the hinges, latches, and aligning pin receptacles. The fiberglass part of the radome is protected by a rain erosion coating and an antistatic coating. Equipped with lightning strips (braided copper) to control possible damage if lightning strikes. This structure houses the forward radar antenna, ESM components, IFF components, and two sensors for the Missile Warning System.
- Aft radome- a fiberglass structure which is used as a housing for the aft radar antenna, the MAD equipment, and two sensors for the Missile Warning System.
- Bombay- the bombay is located under the belly of the aircraft aft of the nosegear. It's function is for transport of weapons and cargo (via a luggage rack).
Operation of the bomb bay doors when personnel or
equipment are in the vacinity of the doors can cause death or serious
injury to personnel and damage to equipment.
Anytime the bomb bay doors are open and hydraulic power is required, an outside observer shall be posted to ensure that the bomb bay area remains clear.
201.1.8 Cabin Pressurization system:
Engine Driven Compressor (EDC)- the normal mode of operation of the air-conditioning and pressurization system employs two engine-driven compressors mounted on engine Nos. 2 and 3. Heated, compressed air from the EDCs is ducted through two air cycle cooling units in the nose wheelwell and then into the flight station and cabin.
- Cabin exhaust fan- air is drawn through the aircraft by the cabin exhaust fan.
- Outflow valve- the air drawn in is ducted overboard through the outflow valve.
201.1.9 Air Conditioning system:
Refrigeration turbine- as the cooled bleed air enters the compresser end of the refrigeration turbine/compressor assembly it is compressed to approximately twice its inlet temperature. It is cooled by rapic expansion.
- Heat exchanger- passing hot engine bleed air through the primary heat exchanger where ram air, forced across the heat exchanger by the aircrafts forward motion, absorbs heat from the bleed air, reducing the air temperature. On the ground and during low-speed operation, ram air is pulled across the heat exchangers by hot air ejected into the heat exchanger exit ducts by the primary and secondary heat exchanger ejectors.
201.1.10 High Rate of Discharge (HRD) bottles:
Engine- the aircraft is equipped with two independent, electrically controlled, high-rate-of-discharge fire extinguishing systems, one for each side of the aircraft. No interconnection is provided between the two systems. When activated, a fire extinguishing chemical (bromotrifluoromethane) is discharged simultaneously into all three zones of the engine selected. Two dual-position transfer switches and four fire extinguisher discharge buttons are used to operate the system. Each system includes two extinguishing agent container bottles located forward of the firewall in the inboard engine nacelles. Each bottle is equipped with two discharge valves, a charging valve and safety disc, and a pressure temperature guage. The bottle is filled with 10.5 pounds of bromotrifluoromethane and is charged to approximately 600 psi with nitrogen. (The nitrogen is used as the expelling agent.) Two discharges are available for one engine on one side, or one discharge for each engine on one side, from the two associated bottles. The discharge can be directed into an engine by depressing the discharge button under the emergency shutdown handle. Expanding gases from the cartridge propel a slug through a frangible disc, allowing the agent to be forced through lines into the nacelle by the nitrogen.
Auxiliary Power Unit- the extinguishing agent is discharged from the flight station by the manual release switch located adjacent to the APU fire detection indicator lights on the right side of the glareshield panel. A continuous-loop fire detection element is installed in the APU compartment. At a temperature of 400°F, the warning lights glow, flight station and cabin warning horns sound, and the APU shuts down. When the intake and exhaust doors close, the fire extinguishing agent automatically discharges.
201.1.11 Discuss the two types of oxygen bottles:
Walkaround- Seven portable oxygen bottles are stowed at the tactical crew stations except station 9 and 10, whose bottles are located at the aft end of the sonobuoy storage bins. On P-3 A/B, four portable oxygen bottles are stored at the bulkhead forward of the starboard forward observer, and three are stored above the aft radar rack. These bottles are normally equipped with diluter-demand regulators and smoke masks. With the regulator set for 100% oxygen and with the user experiencing little or no physical exertion, approximately 22 minutes of oxygen are available. For the same person performing moderate work, consequently breathing at a faster rate, approximately 5 to 10 minutes of oxygen are available per bottle.
- Main- The oxygen system is designed to supply an active flightcrew of three members for approximately 3.5 hours at an altitude of 25,000 feet. Oxygen is supplied from three high-pressure (1,800psi) bottles through three regulators, one for each flight crewmember. A common manifold allows oxygen to be evenly furnished from one or all three bottles through a pressure reducer to the oxygen regulators
201.1.12 State the purpose of the aircraft foul weather systems.
Ice control systems on the P-3 enable the aircraft to perform its mission under various weather conditions and return home safely. Engine bleed air from the 14th stage of the compressor (diffuser assembly) is used to deice the wings and anti-ice the engine airscoop, compressor inlet, and torquemeter shroud assembly. Electrical heating circuits anti-ice and/or deice propellers, empennage, instrument probes, windshield, and side windows.
201.1.13 Describe the following foul weather systems:
Ice detector- probe mounted on the lower starboard side of the fuselage, just aft of the nose radome, provides an indication in the flight station that structural icing conditions exist. The probe contains a pressure switch that is actuated by ice formation and completes a circuit that illuminates the ICING light on the flight station vertical annunciator panel. The pressure switch also completes a probe heating circuit that then melts the accumulated ice. When the ice melts, the pressure switch opens, deenergizing the signal light and probe heater circuitry. New ice accumulation repeats the cycle, causing the ICING light to blink on and off. The frequency of icing light flashes is proportional to the severity of icing conditions.
- Angle-of-attack (AOA) heat- a thermostatically controlled probe heater prevents ice formation on the fuselage-mounted AOA probe.
- Engine ice control- the engine anti-ice systems uses 14th-stage bleed air to prevent ice formation on the engine airscoop, torquemeter shroud, and compressor inlet assembly.
- Propeller ice control (Prop deice)- electric heating elements are used to anti-ice and deice the propellers. Continuous heat anti-icing is applied to the front spinners of all four propellers when the system is turned on. The propeller blade cuffs, aft spinner, and islands are cyclically heated (deiced), one propeller at a time, cycling through all four propellers in sequence 1 to 4. The cycle repeats as long as the system is operating and stops on the propeller being deiced when the switch is turned off.
- Wing deice- 14th-stage engine bleed air us used to remove ice from the wing leading edges. Engine bleed air passes through a motor-driven bleed air valve to a manifold that runs parallel to the wing leading edge. The bleed air then enters one of six ejector assemblies (also called piccolo tubes) that run lengthwise inside each leading edge section. A pneumatically operated modulating valve controls airflow to each ejector assembly. From the ejector assemblies bleed air enters a passage formed by the two layers of the wing leading edge skin. A series of jet action nozzles mounted on each ejector assembly causes the bleed air to mix with air from the plenum area as it enters the leading edges. This warm air mixture circulates aft through the leading edge upper and lower passages and is discharged back into the plenum. As plenum air is displaced by incoming air, it us exhausted overboard through louvers in the aft end of the nacelles.
- Empennage ice control (EMP deice)- portions of the horizontal and vertical stabilizer leading edges are electrically heated in a system that simultaneously anti-ices a series of parting strips while momentary heating power is applied sequentially to deice 20 cycling strips. A two-speed timer motor controls the sequencing of power to the cycling strips. A thermal sensor relay automatically turns the system off if an overheat condition is detected.
- Windshield heating- the three forward windshield panels are electrically heated to prevent icing. The heating consists of separate pilot and copilot systems. Both systems are essentially the same, except that the pilot system heats only the port forward panel, while the copilot system heats the center and starboard forward panels. The heating circuit is cycled off when the temperature reaches a preset maximum (regardless HIGH or LOW selection), and comes on when the temperature drops to a preset minimum.
- Windshield wipers- provides two-speed selection and is controlled individually by the pilot and copilot.
- Pitot heat- two pitot tubes are mounted symmetrically on either side of the lower fuselage, just aft of the nose radome. Each pitot tube is anti-iced by an integral heating element.
201.2.1 How do the following components work together to achieve the systems functions?
Structures- the fuselage structure of the aircraft is of a semimonoque contruction consisting of sheet skin panels, circumferential bulkhead rings, and continuous longitudinal stringers. The fuselage is divided into 3 major components: forward, center, and aft sections.
- Flight controls/surfaces- the primary flight controls are operated from the flight station through conventional cable systems.
- Hydraulics- hydraulically operated booster assemblies for all three primary control surfaces are utilized, and are operated from independent 3,000 psi hydraulic systems No. 1 and No. 2.
201.2.2 Define the following terms:
Anti-icing- refers to a system that prevents ice formation.
- Deicing- refers to a system that removes ice buildup.
201.2.3 Discuss the three methods that generate air conditioning.
- Ambient air
- Air Multiplier
201.2.4 What type of aviators breathing oxygen is used on P-3 aircraft?
Aviators breathing oxygen (MIL-0-2721OD) is supplied in two types- type I and type II. Type I is gaseous oxygen and type II is liquid oxygen. Oxygen procured under this specification is required to be 99.5% pure. The water vapor content must not be more than 0.02 milligrams per liter when tested at 21.1°C (70°F) and at sealevel pressure.
201.3.1 What is the normal operating pressure of the Hydraulic system?
201.5.1 What are the safety precautions pertaining to opening the forward and aft radomes?
The forward and aft radomes shall not be opened when winds are gusting or when wind velocities exceed 20 knots.
201.5.2 What effect does HRD extinguishing agent exposure have on personnel?
Trifluorobromomethane is a flourinated hydrocarbon. It is the most common extinguishing agent used in aircraft fire extinguishing systems. It is a more efficient extinguishing agent that CO2, and under normal atmospheric pressure and temperature, it is a colorless, odorless, and tasteless gas. It exists in a liquid only when contained under pressure.
Trifluorobromomethane if very volatile. It is a nontoxic but a danger of suffocation exists because, like carbone dioxide, it replaces oxygen when breathed.