United States Army Aviation Center of Excellence. Fort Rucker, Alabama JULY 2011 STUDENT HANDOUT

Transcription

1 United States Army Aviation Center of Excellence Fort Rucker, Alabama JULY 2011 STUDENT HANDOUT TITLE: AH-64D INTEGRATED PRESSURIZED AIR SYSTEM (IPAS) FILE NUMBER: (LOT13) PROPONENT FOR THIS STUDENT HANDOUT IS: COMMANDER, 110 TH AVIATION BRIGADE ATTN: ATZQ-ATB-AD Fort Rucker, Alabama FOREIGN DISCLOSURE STATEMENT: This product/publication has been reviewed by the product developers in coordination with the USAACE Foreign Disclosure Officer, Fort Rucker, AL foreign disclosure authority. This product is releasable to students from all requesting foreign countries without restriction D-3

2 Terminal Learning Objective ACTION: Action Identify sources, characteristics, components, operations, warnings, cautions, and advisories of the AH-64D Integrated Pressurized Air System (IPAS). CONDITIONS: In a classroom, given an AH-64D Operator's Manual, the Aircrew Training Manual (TC 1-251) and a computer with IMI software lesson and a student handout. STAANDARD: Identify the sources, characteristics, components, operations, warnings, cautions, and advisories of the AH-64D Integrated Pressurized Air System (IPAS) and receive a Go by correctly answering 4 of 6 questions on scoreable unit 1 of criterion referenced test in accordance with the Student Evaluation Plan. A. ENABLING LEARNING OBJECTIVE 1 ACTION: CONDITIONS: Identify the AH-64D IPAS air sources Given a written test without the use of student notes or references STANDARDS: In accordance with TM Learning Step / Activity 1. IPAS Air Sources Figure 1. IPAS Air Sources a. The primary IPAS air source is bleed air from both engines when both engines are operating. Each engine supplies approximately 50% of the IPAS air required by the using systems. Either engine is capable of supplying 100% of the pressurized air for the IPAS. b. The secondary IPAS air source is bleed air from a single operating engine. D-4

3 c. During ground operations, the Auxiliary Power Unit (APU) supplies bleed air until engines are running and the APU is shut down. d. An Aviation Ground Power Unit (AGPU) can be used as an external air supply for the IPAS when APU or engine operation is not possible, required, or desired. Check on learning: 1. What is the primary pneumatic power source for the Integrated Pressurized Air System (IPAS)? 2. What is the secondary pneumatic power source for the IPAS? 3. What is used for external air source for the IPAS? D-5

4 B. ENABLING LEARNING OBJECTIVE 2 ACTION: CONDITIONS: Identify the characteristics of the AH-64D low-pressure IPAS components Given a written test without the use of student notes or references STANDARDS: In accordance with TM Learning Step / Activity 1. Identify IPAS components Figure 2. Identify IPAS components a. IPAS components The IPAS supplies both high and low pressure air to aircraft systems. The following aircraft components supply, regulate, and distribute low pressure air: (1) Low Pressure Venturi (2) Engine bleed air Pressure Regulator and Shutoff Valves (PRSOV) (3) Flow share sense lines (4) Engine/APU bleed air check valves (5) Air Turbine Starter (ATS) PRSOVs (6) Primary manifold / low pressure manifold (7) Bleed air precooler (8) Precooler bypass temperature thermostat (9) Precooler bypass control valve (10) Bleed air overtemperature switch (11) APU load control valve D-6

5 Figure 3. Low-pressure venturi b. Low-pressure venturi (1) The low-pressure venturi limits the flow of bleed air to 6.5% of the total engine compressor core flow in the event of an IPAS leak. (2) The venturi is mounted directly on the engines at the low-pressure bleed air port and connects to the IPAS ducting leading to the engine bleed air PRSOVs. Figure 4. Engine Bleed Air PRSOVs c. Engine Bleed Air PRSOVs (1) The air pressure from the engines varies depending upon engine power settings, operating parameters, and environmental conditions. Pressures will normally range between 45 to 55 pounds per square inch (psig). D-7

6 (2) The engine bleed air PRSOVs reduce the 45 to 55 psig air pressure from the engines and maintain a normal IPAS pressure of 25 ± 3 psig. (3) During engine cross-bleed starts, the PRSOV START solenoid is de-energized while the ON solenoid remains energized. This action results in a higher manifold pressure (28 to 35 psig) for the engine cross-start when the engine supplying the pressurized air is at a minimum of 95% N G. (4) The engine bleed air PRSOVs are located downstream of the fifth stage low-pressure air outlet of each engine. (5) The PRSOVs are normally closed, pneumatically actuated, solenoid controlled (ON/OFF solenoid and START solenoid), butterfly-type pressure regulating and shutoff valves. (a) The PRSOVs incorporate a position feedback mechanism which is monitored by the SP on aircraft power-up to verify that the PRSOVs are in the commanded positions. (b) The PRSOVs also incorporate a pneumatic servoactuator that is operated by downstream pressure. When downstream pressure changes, the valve will modulate to maintain the bleed air pressure at the desired psig value. (6) The System Processor (SP) monitors for manual control selection of the Engine 1 & 2 PRSOV from the Multipurpose Displays (MPDs) whenever AC power is available. (7) The SP will activate an advisory message when both Engine 1 and Engine 2 BLEED AIR options have been manually selected off from the A/C UTIL page. Figure 5. Flow share sense lines d. Flow share sense lines (1) Flow share sense lines interconnect the PRSOVs to ensure that both engines are supplying an equal amount of bleed air. D-8

7 (2) The stainless steel lines are routed through the aft equipment bay connecting engine one and engine two bleed air PRSOVs. Figure 6. Engine/APU bleed air check valves e. Engine/APU bleed air check valves (1) The engine bleed air check valves prevent: (a) Backflow of pressurized air to the engines while the APU is operating (b) Backflow from engine to engine during single engine operation (2) The APU check valve prevents IPAS system pressure (engine bleed air) from entering the APU bleed air outlet port. (3) An engine bleed air check valve is located downstream of each engine PRSOV in the low-pressure supply duct. The APU check valve is located downstream from the APU load control valve in the low-pressure supply duct. (4) The engine/apu bleed air check valves consist of two semicircular butterfly valves hinged about a pin. (5) When air flow is in the direction of the arrow, the butterfly valves are positioned against the stop tube, opening the flow path. When the flow is in the reverse direction, the butterfly valves are pushed away from the stop tube onto the seat, stopping the flow. D-9

8 f. ATS PRSOVs Figure 7. ATS PRSOVs (1) The ATS PRSOVs control IPAS air flow and pressure into the ATS as commanded by the SP. (2) The ATS PRSOVs are mounted on the accessory section of each engine at the 2 o clock position. (3) The ATS PRSOVs are 28 Vdc, solenoid-controlled, pneumatically actuated, spring-loaded closed pressure regulator and shutoff valves. The ATS PRSOVs incorporate a 2-inch diameter butterfly valve in a flowbody. (4) The SP monitors the engine N G speed signal from the time the engine start sequence is initiated. The SP commands the Electrical Load Center (ELC) to open or close the ATS PRSOVs. Should the SP command the valve open and it does not open within 3 to 3.2 seconds, the SP will activate fault messages to the MPD Data Management System (DMS) page FAULT column and DMS FAULT page. When the SP commands the valve to close and the return signal indicates the valve remained open above 68% N G, the SP will activate an Up-Front Display (UFD) advisory and a FAULT message. D-10

9 Figure 8. g. Primary manifold/low pressure manifold Primary manifold/low pressure manifold (1) The manifold receives low-pressure bleed air from the engine(s), APU, or an AGPU via the ground receptacle, and distributes it to the using systems and components. (2) The stainless steel manifold is located in the aft equipment bay, left of the catwalk, below the precooler. Figure 9. Bleed air precooler h. Bleed air precooler (1) The bleed air temperature from the engines varies depending upon engine power settings, operating parameters, and environmental conditions. Temperatures will normally range between 450 F (232 C) to 500 F (258 C). (2) The bleed air precooler limits maximum normal bleed air supply temperature to 450 F (232 C) by utilizing a 115 Vac vaneaxial fan to provide cooling air flow across the heat transfer surface. D-11

10 (3) The bleed air precooler is on the left side of the aft equipment bay, above the catwalk, immediately aft of the left transmission heat exchanger. (4) The bleed air precooler is a compact, platefin, heat exchanger design. The heat transfer surfaces are rectangular fins and are offset periodically in the flow direction for enhanced heat transfer. (5) Bleed air will be directed through the bleed air precooler depending on the position of the precooler bypass temperature thermostat and control valve. Figure 10. i. Precooler bypass temperature thermostat Precooler bypass temperature thermostat (1) The thermostat functions to control engine bleed air temperature downstream from the precooler below 450 F (232 C). (2) It is housed in the low pressure manifold. (3) The thermostat is a direct-acting thermostat with an inner probe (low expansion material) and an outer probe (high expansion material) used to control pneumatic pressure in response to temperature changes. (4) When high temperature is around the outer probe, the high expansion material lengthens to pull the poppet off the seat. This action vents the actuator supply pressure to ambient air, thereby reducing the control pressure of the precooler bypass control valve, allowing it to operate. As temperature increases, valve actuator pressure decreases and the poppet closes. D-12

11 Figure 11. Precooler bypass control valve j. Precooler bypass control valve (1) The bypass control valve allows IPAS air to bypass the precooler during cold operating conditions, allowing the system to reach normal operating temperatures quicker. (2) The bypass control valve is located in the aft equipment bay, in the precooler bypass line, slightly below and forward of the precooler. (3) The bypass control valve is a normally spring-loaded-closed valve. The valve is opened by system pressure until the bypass temperature thermostat senses an overtemperature condition. This causes the bypass control valve to modulate (close) to increase the flow of air through the precooler. The reference pressure regulator takes variable supply pressure and reduces it to a constant reference pressure. Figure 12. Bleed air overtemperature switch k. Bleed air overtemperature switch (1) The bleed air overtemperature switch monitors the IPAS temperature and provides an overtemperature signal to the SP. D-13

12 (2) The bleed air overtemperature switch is located downstream from the precooler in the low pressure manifold. (3) The switch closes at 490 F (253 C), sending a signal to the SP which activates an advisory for display on the UFD. The switch opens at 450 F minimum (231 C), removing the advisory message from the UFD. Figure 13. l. APU load control valve APU load control valve (1) The load control valve allows APU bleed air into the IPAS manifold after the APU reaches 95% speed. The APU, supplies all pressurized air to the IPAS system even when one or both engines are running. (2) The load control valve is attached to the APU bleed air port. (3) The APU load control valve is a normally closed, electrically opened, 28 Vdc solenoid operated, pneumatic diaphragm metering valve. The load control valve receives all its commands to open or close from the APU ECU. (4) The load control valve is closed during the initiation of the APU start sequence and opens when the ECU determines that the APU has reached 95% speed. During APU shutdown, the APU Start/Stop pushbutton commands the SP to command the ELC2 to de-energize the APU ECU, thereby de-energizing the APU load control valve to the closed position. Check on learning: 1. Which components maintain the pressure of low pressure Integrated Pressurized Air System (IPAS) air? 2. Which component limits maximum normal bleed air supply temperature to 450F? 3. When does the Auxiliary Power Unit (APU) load control valve open during APU starts? 4. At what temperature does the overtemperature switch close? D-14

13 C. ENABLING LEARNING OBJECTIVE 3 ACTION: CONDITIONS: Identify the components on the AH-64D that use low pressure IPAS Given a written test without the use of student notes or references STANDARDS: In accordance with TM Learning Step / Activity 1. Identify the components that use low pressure IPAS Figure 14. Low pressure IPAS driven components a. Low pressure IPAS driven components The following aircraft systems use low pressure IPAS air: (1) Environmental Control System (ECS) (2) Engine Air Turbine Starters (ATS) (3) Fuel system components (4) Ice detector probe (5) Nitrogen Inerting Unit (NIU) (6) Engine firewall/cooling (7) Utility receptacle (8) Canopy defog b. Environmental Control System (ECS) The ECS uses IPAS air for heating the crewstations and the Air Particle Separator (APS). Additionally, pressurized IPAS air is routed to each crewstation through the canopy defog shutoff valve to defog the side windows. c. Engine ATS The IPAS applies pressurized air to the air turbine starter impeller, causing the ATS shaft to turn. Pressurized air is routed to the ATS PRSOV from the combined Engine 1 and 2 and APU bleed air line before it enters the precooler. D-15

14 d. Fuel system components The fuel system pressure regulator valve reduces the IPAS pressure down to psig for use by the fuel boost pump, fuel transfer pump, and auxiliary fuel tank transfer/shutoff air valve. e. Ice detector probe aspirator f. NIU The IPAS supplies pressurized air to an outlet aft of the ice detector probe to create a constant airflow past the ice detector probe by inducing a low-pressure area aft of the probe. The NIU cools, dries, and removes oxygen (thereby increasing nitrogen concentration) from IPAS pressurized air which is routed to the fuel cells to inhibit explosive vapor build up. g. Engine firewall/cooling The IPAS supplies pressurized air to the engine louver actuator to close the engine louvers when the engine fire extinguishing system is activated from the cockpit. The louvers also designed to cool the engine and transmission. h. Utility receptacle The utility air receptacle provides a connection to the IPAS for troubleshooting and for air pressure to operate air-powered tools. A flow-restricting orifice just upstream of the utility air receptacle decreases the IPAS outlet pressure to 30 pounds per square inch gauge (psigg). i. Canopy defog The canopy defog system prevents or removes moisture (fogging) on the inside canopy side panels of both crewstations. Defogging is accomplished by mixing Integrated Pressurized Air System (IPAS) air with crewstation conditioned air and directing it against the four canopy side panels. NOTE: The engine cooling door actuators are held closed by 5th stage bleed air from each engine and not by air from the IPAS manifold. There is no electrical interface so when an engine is shut down the door for that engine will open. Check on learning: 1. What does the Environmental Control System (ECS) use IPAS air for? 2. What does the Nitrogen Inerting Unit (NIU) do with IPAS air? 3. What does the fuel system pressure regulator valve reduce IPAS pressure down to? D-16

15 D. ENABLING LEARNING OBJECTIVE 4 ACTION: Identify the components of the AH-64D high pressure IPAS CONDITIONS: Given a written test without the use of student notes or references STANDARDS: In accordance with TM Learning Step / Activity 1. Identify high pressure IPAS Figure 15. High pressure IPAS components a. High pressure IPAS components (1) High pressure manifold (2) High pressure check valves (3) Primary and utility hydraulic reservoir pressure regulators (4) Primary and utility hydraulic reservoir pressure relief valves D-17

16 Figure 16. b. High pressure manifold High pressure manifold (1) The high-pressure manifold supplies regulated high-pressure air to the hydraulic system reservoirs. (2) The high pressure manifold is routed from a connection on each engine s diffuser section through the aft equipment bay to the primary and utility hydraulic system reservoirs. c. High pressure check valves (1) The high pressure check valves are in-line, one-way pneumatic check valves which prevent: (a) Backflow of pressurized air to the engines while the APU is running and supplying the bleed air requirements (b) Backflow of the 5th stage bleed air from engine to engine (c) (c) Reverse airflow from the engines back through the APU (2) The check valves for engine No. 1 and the APU are located in the aft equipment bay area underneath the bleed air precooler, close to the No. 1 engine firewall. Engine No. 2 check valve is also located in the aft equipment bay area just inboard from engine No. 2 firewall. D-18

17 Figure 17. Hydraulic reservoir pressure regulators d. Primary and utility hydraulic reservoir pressure regulators (1) The hydraulic reservoir pressure regulators are factory calibrated to reduce high-pressure bleed air to 31 ± 3 psig for the primary and utility hydraulic reservoirs. (2) The primary and utility hydraulic reservoir pressure regulators are in the aft equipment bay. The primary pressure regulator is on the deck forward of the bleed air precooler. The utility pressure regulator is on the deck behind the L325 access door. (3) These units are normally open, pressure regulators. Inlet pressure is ported into the base of the regulator, past the poppet, and to the regulator outlet. The outlet pressure bleeds through the damping orifice and acts against the regulator diaphragm. As the outlet pressure increases, the diaphragm force increases and acts against the regulator spring to stroke the poppet toward its seat. The movement of the poppet toward its seat causes a decrease in the outlet pressure. When the outlet pressure decreases, the diaphragm force decreases and the poppet strokes away from its seat. In this manner a constant outlet or downstream pressure is maintained. An honest orifice is provided to allow accurate D-19

18 Figure 18. Hydraulic reservoir pressure relief valves e. Primary and utility hydraulic reservoir pressure relief valves (1) Primary and Utility hydraulic pressure relief valves are installed to limit pressure in case of pressure regulator failure. In the event a pressure regulator fails in the open position, the poppet will off seat to maintain bleed air pressure to the respective hydraulic reservoir at 55 1 psig. (2) The primary and utility hydraulic reservoir regulator pressure relief valves are located in the aft equipment bay, one left of the utility manifold, the other aft of the primary manifold. (3) The pressure relief valves are spring-loaded closed poppet valves. (4) In the event a pressure regulator fails in the open position, the poppet will off-seat to maintain bleed air pressure to the respective hydraulic reservoir at psig. Check on learning: 1. Which components control the pressure of high-pressure air? 2. What is the purpose of the Engine No.1 and Engine No. 2 high-pressure check valves? 3. The primary and utility hydraulic reservoir pressure regulators reduce high-pressure bleed air to what pressure? D-20

19 E. ENABLING LEARNING OBJECTIVE 5 ACTION: Identify the operation of the IPAS CONDITIONS: Given a written test without the use of student notes or references STANDARDS: In accordance with TM Learning Step / Activity 1. Identify IPAS operations Figure 19. IPAS operations a. Automatic operation IPAS operation is normally a completely automatic function of Aircraft Subsystem Management (ASM) dependent on the operational status of the APU and engines. (1) Operation with only the APU on The APU supplies air pressure to the low-pressure manifold through the APU load control valve. The pressurized air is routed through the low pressure manifold to the following: (a) Engine bleed air precooler When pressurized air from the low-pressure manifold flows to the precooler, the precooler bypass temperature thermostat senses the air temperature. The precooler bypass thermostat opens or closes the precooler bypass valve to allow air to pass through or around the precooler to limit the air temperature to a maximum temperature of 450 F. Pressurized air from the precooler is then routed to aircraft loads. D-21

20 (b) During APU only operations, pressurized air from the low pressure manifold flows through the hydraulic reservoir check valve and pressurizes the primary and utility hydraulic reservoirs. (c) Air turbine starter PRSOVs APU supplied air pressure passes through the air turbine starter PRSOVs to the Engine ATS when the engine start switches are activated. (2) Operation after the engines are started Once one or both engines are at 101% N P the high-pressure manifold is pressurized from the engine diffuser. The lowpressure manifold will continue to be pressurized by the APU through the APU load control valve until the APU is shut down. (3) Operation after the APU is shut down (engines running) (a) Both engine bleed air PRSOVs are automatically commanded open by the SP if their N G is greater than 80%. This is indicated by solid dots on the Aircraft Utility (UTIL) page BLEED AIR 1 and 2 VAB labels. (b) The APU load control valve is closed and the engine bleed air check valves will open and allow the engines to pressurize the system. (c) The pressurized airflow is identical to the pressurized airflow during APU operations. Figure 20. Aircraft Utility Page D-22

21 b. Manual operation (1) The engine PRSOVs may be commanded to open or close by using the aircraft UTIL page BLEED AIR 1 and 2 buttons. MPD control of the engine bleed air PRSOVs is provided to independently isolate the engine bleed air sources in the event of a bleed air over temperature condition. (2) The engine 1 and 2 bleed air PRSOVs have a hard-wired interlock to the ENG 1 and Engine 2 FIRE pushbuttons. When a pushbutton is activated, the engine 1 or 2 bleed air PRSOV will close. There is no SP control for this action. (3) Powering the APU down via the APU ON/OFF pushbutton commands the SP to command ELC2 to de-energize the APU ECU thereby de-energizing the APU load control valve to the closed position. (4) The APU load control valve has a hard-wired interlock to the APU fire pushbutton. When the pushbutton is activated, the APU load control valve is closed. There is no SP control. Check on learning: 1. Where are the bleed air controls located? 2. When one or both engines are at 101% N P and the APU is still operating, what supplies pressurized air to the low-pressure manifold? 3. When does air from the low-pressure manifold pressurize the primary and utility hydraulic reservoirs? D-23

22 F. ENABLING LEARNING OBJECTIVE 6 ACTION: CONDITIONS: Identify the warnings, cautions and advisories associated with the IPAS Given a written test without the use of student notes or references STANDARDS: In accordance with TM Learning Step / Activity 1. Warnings, cautions and advisories associated with the IPAS a. There are no warnings or cautions associated with the IPAS. b. Advisory messages are presented to crewmembers via the UFD and MPD Page formats. A listing of IPAS advisories and their cause is presented below. Advisory Messages UFD TEXT PARAMETER OR FAULT MPD TEXT BLEED AIR HOT These messages occur when the system BLEED AIR HOT processor detects a bleed air over temperature (> 490 F) condition. ENG 1 BLD AIR FAIL This message occurs when the system ENG1 BLD AIR FAIL processor commands the engine 1 bleed PRSOV OPEN or CLOSED, and it does not move as directed. ENG 2 BLD AIR FAIL This message occurs when the system ENG2 BLD AIR FAIL processor commands the engine 2 bleed PRSOV OPEN or CLOSED, and it does not move as directed BLEED AIR OFF This message occurs when engine 1 and 2 bleed air sources have been manually shut off BLEED AIR OFF Check on learning: 1. What does the advisory BLD AIR1 on the UFD indicate? 2. What does the advisory BLD AIR OFF indicate? 3. What does the advisory BLD AIR HOT indicate? D-24

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