Combined aircrew systems tester (CAST)

The invention enables testing of nearly all aircrew equipment including COMBAT EDGE system components which include a mask, a G-suit, communication systems, and a goggle. A gas system includes an input filter, a first compressor comprising at least one blower, preferably three blowers connected in series, a second compressor, a first flow sensor, a second flow sensor, a first flow valve, a second flow valve, a regulator, a first pressure sensor, a second pressure sensor, a first pressure valve, a second pressure valve, and a controller. The second compressor produces a lower flow at a higher pressure than the first compressor. When the G-suit inflates, initially there is a large change in volume without much change in pressure, and then, as the G-suit fills and becomes firm, the change in volume slows down and the rate of the pressure increases. A normal breathing test, a preflight test, a fit test, a G-suit leak test and two dynamic flow leak tests are conducted.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a combined aircrew systems tester, and more particularly, to a combined aircrew systems tester enabling functional testing of aircrew equipment.

2. Description of the Background Art

Life support systems are very crucial for members of an aircrew of aircraft and especially high performance aircraft. Life support systems include COMBAT EDGE (combined advanced technology enhanced design G-ensemble) system components. The system includes a G-suit, an oxygen mask, goggles, and a communication equipment. Specifically, the COMBAT EDGE system includes the MBU-20/P Oxygen Mask, CSU-17/P Vest Assembly, HGU-55/P Helmet with occipital bladder, CRU-94/P Integrated Terminal Block or PBG (pressure breathing for Gs) Chest Mounted Regulator or both CRU-94/P Integrated Terminal Block and PBG Chest Mounted Regulator, and all associated Anti-G garments.

Life support systems are very important for the aircrew and therefore, it is extremely important that such vital systems be properly tested. If any of the above systems do not work, a pilot for instance may be unable to control the aircraft.

Earlier systems had different testing units for each type of life support. A separate cumbersome unit would be needed for testing an oxygen mask and another separate large unit would be needed for testing the anti-G suit. This is expensive and very awkward for users to test their equipment at different stations while for instance they are wearing such equipment. Moreover, the power sources for such equipment are usually not commonly available because of the high power necessary to drive such complicated devices.

Particularly, a conventional tester for an oxygen mask requires a separate high pressure source of breathing air/oxygen. It is awkward for users to bring the tester and the separate high pressure source.

For the foregoing reasons, there is a need for a tester that can be inexpensively and efficiently test life support equipment.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to have an integrated unit that can functionally test the various aircrew equipment.

It is another object to have an aircrew systems tester that can test all of the aircrew life support equipment and communication systems.

It is yet another object to have a unit that can test the aircrew life support equipment and yet not require much power for operation.

It is still yet another object to have a unit that tests the aircrew life support equipment and yet not require high pressure air/oxygen cylinders.

It is still another object to have a unit that tests the aircrew life support equipment and significantly reduces supporting man-hours, deployment costs and mobility footprint.

It is still further another object to have a life support system tester that is able to operate in a chemical warfare environment.

To achieve the objectives of the present invention, there is provided a tester including a gas system which includes an input filter located in an inlet port, the input filter filtering an air to prevent foreign particles from entering the gas system, a first compressor compressing the air, the first compressor comprising at least one blower, a speed of the blower depending on a voltage applied to the blower, a second compressor compressing the air, the second compressor producing a lower flow than the first compressor, the second compressor producing a higher pressure than the first compressor, a first flow sensor detecting a flow of the compressed air and a leaking of the aircrew systems, a second flow sensor detecting the flow of the compressed air and the leaking of the aircrew systems, a first flow valve mounted for controlling the flow of the compressed air to the first flow sensor, a second flow valve mounted for controlling the flow of the compressed air to the second flow sensor, a regulator regulating a pressure of the second system, a first pressure sensor detecting a pressure of the mask, a second pressure sensor detecting the pressure of the second system, a first pressure valve for controlling the pressure of the first system, a second pressure valve for controlling the pressure of the second system, and a controller controlling an operation of the gas system. The inlet filter designed to accept a C2 (chemical) filter. The gas system is particularly suitable for testing a mask and a G-suit. It is preferred that the first compressor comprises three regenerative blowers, a first blower, a second blower, and a third blower, connected in series. It is preferred that each of the three regenerative blowers has 21 inch H2O of a maximum output pressure. In a preferred embodiment, the first compressor compresses the air until a G-suit pressure reaches 55 inch H2O, the second compressor starts to compress the air when the G-suit pressure is about 55 inch H2O and finishes when the G-suit pressure is about 70 inch H2O. The first flow sensor is able to measure the flow from 0 to 10,000 cc/min (cubic centimeters per minute), and the second flow sensor is able to measure the flow 0 to 300 cc/min. The first flow valve and the second flow valve determine which sensor is used. The gas system further includes a digital indicator reading out data outputted from the first and second flow sensors. The gas system further includes a first limit valve for limiting a pressure of the first system. The operation of the gas system is controlled by a main printed circuit board (PCB) which uses CMOS (complementary metal oxide semiconductor) logic. The present invention further includes a speed control printed circuit board (PCB) which controls the first compressor by controlling a voltage applied to the second first compressor.

The tester of the present invention includes a first unit for testing a mask, a second unit for testing a G-suit, and a third unit for testing a communication system. The tester can further includes a fourth unit for testing a goggle. Since the tester of the present invention is self contained and integrated, a control panel of the tester of the present invention has a plurality of switches and indicators for controlling the tests for the life support systems of an aircrew member. The third unit preferably includes an input accommodating a microphone, an input accommodating headset, and two inputs for carbon microphones. The third unit further includes a built-in continuity tester. The third unit can further includes an accommodation of a second headset and microphone accommodating a first user to communicate with a second user.

A method of operating a gas system for testing aircrew systems which includes a mask and a G-suit is comprised of the steps of selecting a test mode between the test mode for the normal breathing and the test mode for the PBG breathing, filtering an ambient air with a C2 filter, compressing the air, detecting a flow of the air, and detecting a pressure of the mask or G-suit. When the mask test mode is selected, the step of compressing the air further includes the step of turning on the first compressor. When the PBG mode test is selected, the step of compressing the air further includes the steps of turning on the first compressor until a G-suit pressure reaches 55 inch H2O, turning off the first compressor and turning on the second compressor when the G-suit pressure is about 55 inch H2O, and turning off the second compressor when the G-suit pressure is about 70 inch H2O. The first compressor is controlled by adjusting a voltage applied to each of the first, second, and third blowers and by deciding how many blowers are turned on.

With this configuration, the present invention enables functional testing of nearly all aircrew equipment including the COMBAT EDGE (Combined Advanced Technology Enhanced Design “G” Ensemble) system components.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is an integrated unit that can functionally test the various aircrew equipment. Life support systems include COMBAT EDGE (combined advanced technology enhanced design G-ensemble) system components. The system includes the MBU-20/P Oxygen Mask, CSU-17/P Vest Assembly, HGU-55/P Helmet with occipital bladder, CRU-94/P Integrated Terminal Block or PBG (pressure breathing for Gs) Chest Mounted Regulator or both CRU-94/P Integrated Terminal Block and PBG Chest Mounted Regulator, and all associated Anti-G garments.

A functional diagram of a gas system for a combined aircrew system tester (CAST) is shown inFIG. 1.

The gas system of the tester provides two air sources. One is for a mask or a vest, and the other is for a G-suit (a suit designed to counteract the physiological effects of acceleration on an aviator or astronaut—called also called an anti-G suit). The air for the G-suit is provided through a G-suit port and the air for the mask/vest through the mask port. These air sources are used to perform maintenance and preflight testing of the pilot's life support equipment. The mask port air is used to test the pilot's oxygen mask and COMBAT EDGE gear. There are two modes of mask testing, ‘normal’ and ‘PBG’ (Pressure Breathing for G (acceleration force of gravity)).

Referring toFIGS. 1 through 4, air for the mask starts by passing through an input filter101. The ambient air is inputted through an inlet port. A screen mesh filter assembly screws into the inlet port to prevent particles from entering the air stream. The thread on the inlet port is designed so that it can accept a C2 (chemical) filter246used for chemical warfare. This feature makes it possible to use the tester in a chemical environment. All the air outputted by the tester passes through the C2 when it is installed.

Then, the air for the mask is compressed by a low-pressure compressor system102.

The low-pressure compressor system102includes at least one blower but preferably includes at least three regenerative blowers102a,102band102cconnected in series to generate the necessary pressure and flow. The output pressure is determined by the speed of the blowers102a,102band102cand how many blowers102a,102band102care turned on. The voltage applied to each of the blowers102a,102band102ccontrols the speed. If the voltage decreases, the speed decreases and the output pressure is decreased. The voltage is controlled by a speed control circuit, which is part of the speed control PCB (Printed Circuit Board, PCB3).

Then, the air for the mask passes through one of two flow sensors106,107, which are used to alert the user that his or her equipment is leaking and to measure the leak rate. One flow sensor is a high flow sensor106which measures flow from 0 to 10,000 cc/min (cubic centimeters per minute) and the other flow sensor is a low flow sensor107which measures flow from 0 to 300 cc/min. A mask control valve104and a low flow valve105determine which sensor is used. One of two valves104and105which are normally closed is open to permit the air to flow through one of the flow sensors106and107. The output from the flow sensor106or107is fed into a digital indicator274(FIG. 2) to indicate flow. The indicator274reads out in the appropriate units. Its range is set by an embedded processor on a main PCB (Printed Circuit Board, PCB1).

These sensors are excited with 10.0 VDC (voltage of direct current). At zero flow their output is 1.0 VDC (voltage of direct current). At full scale the output is 5.0 VDC (voltage of direct current). The low flow sensor107is not quite linear. To compensate for this, five linear curves are fitted to the flow versus voltage curve. The slopes of these five curves are programmed into the digital indicator274that is used to indicate flow.

Next, the air passes through a check valve118and flows out the mask port242. The check valve118prevents foreign materials from entering the gas system of the tester. A pressure switch111and a mask pressure sensor112monitor the mask port pressure. They are used to control and limit the mask port pressure. The mask pressure sensor112converts pressure to voltage. The voltage is fed into the digital indicator270where it is converted to a digital signal, which is presented as number scaled in engineering units. This number is updated 13 times a second. The indicator has three logic high outputs, which output when the pressure exceeds their set pressure. In addition, the pressure switch111is connected to the mask pressure sensor112. The pressure switch111is normally closed, and is preferably set to open at 18 in (inch) H2O.

A mask limit valve114and a backup mask limit valve115are also provided for controlling the mask port pressure.

The air for the G-suit is produced by multiple compressors102a,102b,102cand103. At pressures below 55 in H2O, the low-pressure compressor system102compress the air. At pressures above 55 in H2O, a high-pressure compressor103compresses the air. This is done to minimize the amount of time to inflate the G-suit. The low-pressure compressors (with regenerative blowers)102a,102band102cproduce high flow at relatively low pressures while the high-pressure compressor103produces low flow but can compress the air to a higher pressure. This combination works particularly well when inflating the G-suit because when the G-suit inflates, initially there is a large change in volume without much change in pressure, and then, as the G-suit fills out and becomes firm, the change in volume slows down and the rate the pressure increases.

A G-suit regulator enable valve109and a G-suit regulator108are provided for regulating the G-suit pressure. The G-suit regulator enable valve109is normally closed. When the G-suit pressure increases up to a certain pressure, the G-suit regulator enable valve109is opened to vent the G-suit regulator108.

A G-suit control valve110is further provided for controlling the G-suit pressure.

With this configuration, the present invention does not require a separate high pressure source of breathing air and oxygen.

As explained above, the present invention is self contained. Thus, a control panel of the combined aircrew systems tester of the present invention has a plurality of switches and indicators for controlling the tests for the life support systems of an aircrew member.

FIG. 2shows a preferred embodiment of the control panel.

The mode select portion201includes a mode select switch201A preferably provides for two dynamic flow leak testing (high leak (‘LK-HI’)201D and low leak (‘LK-LO’)201C), a G-suit leak testing (‘LK-GS’)201B, and one mask testing (‘mask’)201E.

The pressure select switch202is preferably provided for 41M, 43M, or 45M (where M stands for 1000). Thus, the air is provided at one of four positive pressures; normal, 41M, 43M, or 45M.

The test select switch203provides for a PBG breathing testing (‘PBG’), a normal breathing testing (‘normal’), and ‘off’. The test select switch203is preferably a three-position toggle switch. The test select switch203drives two de-bouncers332,334, the PBG and the normal logic steps.

A leaking indicator235is also included in the control panel200.

The communication section includes audio input A222and B224, a carbon headset input226, a press to test (‘PTT’) jack228, a continuity status of a microphone230, a continuity status of the earphone232, a microphone “on” indicator234, an audio select switch236that can be switched to continuity test mode236a, ‘LIS/TLK1’ (listen/talk1)236b, or ‘LIS/TLK2’236c. A port for the goggle238and a ‘G-suit’ button240are included along with a mask port242. Indicators244aand244brelating to the PBG (pressure breathing for Gs) are also included. Reference244bindicates that ‘PBG timed out’,244aindicator concerns the ‘PBG’. The control panel200also includes the filter246. There are ports for the power248and the battery250. A switch or indicator for tare252is along with a hold254, and a reset256indicator or switch. A G-suit ready indicator258is also included along with a G-suit testing on/off switch260and a pressure control knob262. The tester also includes a G-suit port pressure displays268, a mask port pressure display270, a time display272, and a high and low flow display274. The displays can be a digital display such as light emitting diodes, or liquid crystal display or other types of indicators.

The operation of the tester is explained in more details as follows.

To test the mask when the aircrew does not wear COMBAT EDGE, the user selects a mask mode of operation by pressing the mode select switch201. The user selects a desired breathing pressure by pressing the pressure select switch202. Then the test select switch203is toggled to the ‘normal’ position, which starts air flow out of the mask port at slight positive pressure. Then the press to test button204is pushed to cause the air pressure to increase to the pressure selected. The air is preferably provided at one of four positive pressures; normal, 41M, 43M, or 45M. When the mask mode has been selected and the test select switch is in the ‘normal’ position, the mask control valve104opens permitting the air to flow out the mask port. When operating in the normal mask mode, the air outputted through the mask port is provided at a pressure from 1 to 10 in H2O.

The PBG (Pressure breathing for G) breathing is used to perform preflight tests and fit tests while the users are wearing COMBAT EDGE. The users wearing COMBAT EDGE are required to take the preflight test on their masks at PBG breathing pressure level. This test is performed at a breathing pressure of 16 in H2O with the G-suit not inflated. When the G-suit is not inflated, it is dangerous to breathe air at pressures much above 16 in H2O. When the mode select switch201is set to ‘mask’ and the test select switch203is in the ‘PBG’ position, the air flows from mask port at normal pressure. When the press to test button204is depressed, the breathing pressure increases to 16 in H2O. The user verifies that he or she is breathing normally, verifies proper mask functions and notes that their vest starts to inflate. Then the user momentarily stops breathing to test a leak. A light of the leaking indicator235will go out if there are no leaks greater than 5.5 lpm (liters per minute). When the press to test button204is pressed, the speed of the low-pressure compressor system102increases.

After a user is initially fitted with COMBAT EDGE equipment, a fit test is performed. This test is similar to the preflight test except the fit test is performed at32in H2O. The user has to be sitting down to perform this test. The fit test starts by performing the preflight test. Then the mask port pressure is increased slowly to 32 in H2O by adjusting the pressure control release and knob262until the air pressure reaches 32 in H2O. Then the preflight test is repeated.

During preflight and fitting a red light turns on when flow exceeds 5.5 lpm. The user momentarily holds his or her breath to check for leaks. If there are no leaks, the leak light is turned off.

The voltage from the low flow sensor107is compared with a preset voltage that is equivalent to the sensor output when the flow is 5.5 lpm. When the voltage exceeds the preset voltage, the light of the leaking indicator235is turned on.

In order to do the preflight test safely, the G-suit has to be inflated. The low-pressure compressor system102and the high-pressure compressor103provide the air for the G-suit. When the G-suit switch260is turned on, the G-suit control valve110opens and the low-pressure compressor system102is turned on at its maximum operating speed so that the air rapidly fills the G-suit to its final approximate shape. When the G-suit pressure reaches 55 in H2O, as sensed by G-suit pressure sensor113, the high-pressure compressor103takes over filling the G-suit to its final pressure. The output of the G-suit pressure sensor113is fed into the digital indicator/controller268. The indicator268turns the input voltage into a digital signal and processes it, rescaling it into engineering units and outputting it in the form of a number presented on the indicator. The G-suit pressure is maintained at 60 in H2O by the G-suit regulator108. If the G-suit pressure exceeds 70 in H2O, the high-pressure compressor103is turned off to limit the G-suit pressure to 70 in H2O. After the G-suit pressure stabilizes at 60 in H2O, the user turns off the G-suit switch260.

The G-suit is periodically checked for leakage. To do this, the G-suit is pressurized to 138.4 in H2O (5 psi, pounds per square inch) and monitored for a change in pressure over an interval of time.

When the mode select switch201is in ‘LK-GS’ and the G-suit switch260is turned on, the G-suit regulator enable valve109is turned on to disable the G-suit regulator108, allowing the G-suit pressure to rise to pressures greater than 60 in H2O, which is a normal G-suit operating pressure. The high-pressure compressor is turned off at 138.4 in H2O. When the pressure reaches 138.4 in H2O, the power to the G-suit control valve110and the high-pressure compressor103is turned off to limit the pressure to 138.4 in H2O. Once the pressure stabilizes, the user turns off the G-suit switch260to close off the G-suit. The tare switch252is pushed for zeroing the time and G-suit pressure. At 120 seconds the hold button254is pressed for holding the indicated change in time8and change in G-suit pressure. From these changes, the leak rate can be obtained.

When the mode select switch201is in the ‘LK-HI’ position (indicator201D), the mask control valve104is opened. The low flow valve105remains off for directing all the flow through the high flow sensor106.

When the mode select switch201is in the ‘LK-LO’ position (indicator201C), the mask control valve104is closed. The low flow valve105is turned on for directing all the flow through the low flow sensor107.

A second method used to verify the oxygen equipment seals is to measure a drop in pressure over an interval of time. The component under the test is attached to the mask port and is pressurized to 32 in H2O by setting the mode to ‘mask’ and the test select switch203to ‘PBG’. The press to test button204is pushed and the pressure control knob262is adjusted until air pressure reaches 32 in H2O. After the pressure has stabilized, the press to test button204is released to cut off the air source. The tare switch252is pressed to start a timer and zero the pressure indicator,268and270. At a prescribed time the hold switch254is pressed to hold the timer and the pressure indicator readings. If the change in pressure is less than a prescribed amount in the prescribed time, the leak rate is within tolerance.

The present invention is designed to address safety issues with the following features.

When performing COMBAT EDGE testing, it is necessary to expose the user to excessive breathing pressures. Exposure to excessive breathing pressure can hurt the user. It is only safe under curtain conditions and for limited periods of exposure. Under no circumstance should the breathing air pressure exceed 34 in H2O.

The present invention compresses the filtered ambient air to pressures close to the maximum allowable output mask pressure, while the conventional testers start with air that is compressed to pressures that are orders of magnitude greater than the maximum allowable output mask pressure. If the step down regulation system in the conventional pressures completely fails, the user is exposed to pressures that many times greater than what is safe. On the other hand, the user of the present invention would be exposed to pressures not higher than the maximum allowable mask output pressure.

As stated before, the blowers102a,102b, and102cprovide the breathing air. The maximum pressure that can be developed by each of the blowers102a,102b, and102cis 21 in H2O when being driven by main power supply voltage at zero flow. If all pressure limiting systems were to fail, the maximum breathing pressure that could be developed to 63 in H2O at zero flow, which is comparable to the maximum safe pressure of 34 in H2O. When the user is breathing, the pressure is significantly less.

Another safety feature of the present invention is a mask pressure limiting system. In the preflight test, if the pressure increases above 18 in H2O, the power to the mask limit valve114is cut, venting the system through a check valve119. This check valve119prevents back flow through the mask limit valve114when the user is inhaling. In addition, the mask port pressure is limited to 34 in H2O under all circumstances. The backup mask limit valve115operating current is passed through a pressure limit switch111set to open at 34 in H2O. The backup mask limit valve115is a normally open valve. When the pressure limit switch111opens, the operating current is interrupted to open the backup mask limit valve115.

The method of controlling the CAST is described in more detail below.FIG. 4A through 4Sillustrate schematic diagrams of sections4A through4S, respectively of the overall block diagram ofFIG. 3of the present invention. The schematics of4A through4S are sectioned to show the entire schematic of the present invention. Some portions may overlap in order to accurately show the connections between the individual elements.

The operation of the gas system is controlled by the main printed circuit board (PCB 1), which uses CMOS (complementary metal oxide semiconductor) logic to control the overall operation. There are two pressure sensors, two digital indicators, five switches and one potentiometer that input and drive the logic functions located on the main PCB (Printed Circuit Board, PCB1). The logic outputs control the speed control PCB (PCB3), and the valves that control flow.

All logic inputs are derived from either switch closures or TTL (transistor-transistor logic) located in the digital indicators. They pass through de-bouncers. The de-bouncers clean up these inputs and turning them into single pulse square waves with CMOS logic high levels.

The outputs refer to either compressor motors or valves. The valve outputs and the high-pressure compressor output are located on the main PCB (PCB1). They include an opto isolator and power relays. This is done to protect the CMOS logic from inductive spikes that occur when switching a valve. The high-pressure compressor output is located on the main PCB (PCB1) and the low-pressure compressors outputs are located on the speed control PCB (PCB3).

A mode select circuit includes the mode select switch201, a momentary push button driving a Johnson Counter (also known as a twisted-ring counter) (seeFIG. 4D). The Johnson counter provides the ‘MASK’ for the mask testing, ‘LK-HI’ for the high-leak testing, ‘LK-LO’ for the low leak testing, and ‘LK-GS’ for G-suit leak testing. It drives four buffers, which drive four LEDs (light emitting diodes)201B,201C,201D,201E, which indicate the mode that is selected. The pressure select circuit works the same way.

The test select circuit starts with a three-position toggle switch203, which drive two de-bouncers. The de-bouncer outputs are the ‘PBG’ and ‘normal’ logic steps. (SeeFIG. 4F)

The press to test switch204and the G-suit switch260drive two de-bouncers. Their outputs are the ‘TST’ and ‘GSUIT’ logic steps.

With respect to the G-suit pressure sensor113and the mask pressure sensor112, the output from the G-suit pressure sensor113is fed into a digital indicator268. The indicator268turns the input voltage into a digital signal and processes it, resealing it into engineering units and outputting it in the form of a number presented on the indicator268. It also provides a TTL logic high output at 55, 70 and 138.4 in H2O. The indicator provides 10-volt excitation for the pressure transducer. The mask transducer (sensor)112works the same except it outputs TTL logic high outputs at 1, 18 and 34 in H2O. (SeeFIG. 4, part O)

The G-suit regulator enable valve109is normally closed. It is turned on to vent the G-suit regulator108to regulate the G-suit pressure (GSP) to 60 in H2O, which is the normal suit operating pressure. It is turned off when performing a G-suit leak test (LK-GS).

The G-suit control valve110is normally closed. In any mode select position other than ‘LK-GS’, the G-suit control valve110is turned on until the G-suit pressure reaches 70 in H2O. In the ‘LK-GS’ position, the G-suit control valve110is turned on until the G-suit pressure reaches 138.4 in H2O.

With respect to the low flow valve105, this valve105is turned on until the mask pressure (MP) reaches 34 in H2O when the press to test switch204is pressed in the ‘LK-LO’ position

The mask limit valve114is normally open. When the test select switch203is in ‘normal’, the mask limit valve114is closed when the MP (mask pressure) is less than 18 in H2O. In the ‘LK-HI’ or ‘LK-LO’ or the test select in the ‘PBG’ position, the mask limit valve114is on until mask port pressure reaches 34 in H2O.

The mask control valve104is normally closed. In the ‘LK-HI’ position, the mask control valve104is on until the mask pressure reaches 34 in H2O. In the ‘mask’ position, the mask control valve104is on when the test select switch203is in the ‘PBG’ or ‘normal’ positions.

The backup mask limit valve115is normally open. It is closed at the same time the mask limit valve114is closed. Its power passes through the pressure switch111. If the mask pressure exceeds 34 in H2O, the pressure switch111opens to cut off power to the backup mask limit valve115. The backup mask limit valve115opens to reduce the mask port pressure.

The ‘High-Pressure Compressor’ output turns on the high-pressure compressor103at 55 in H2O and off at 70 or 138.4 in H2O. In the ‘LK-GS’ position, it turns off at 138.4 in H2O.

The ‘Low-Pressure Compressor1’ output turns on the low-pressure compressor1102awhen the test select switch203is in either the PBG or ‘normal’ positions. If the mode select switch201is in the ‘LK-HI’ or ‘LK-LO’ position, the blower102ais on. This is done to provide positive flow whenever the mask port is in use.

The ‘Low-pressure Compressor2’ output and the ‘Low-Pressure Compressor3’ output turn on the low-pressure compressor2as ‘102b’ inFIG. 1and the low-pressure compressor3as ‘102c’ inFIG. 1when the test select switch203is in the ‘normal’ or ‘PBG’ position and the mask pressure drops below 1 in H2O. When the test switch203is in the ‘normal’ and the mode select switch is ‘LK-LO’ or ‘LK-HI’ position, the low-pressure compressor2and3102band102care turned on when the press to test switch204is pushed. When the test switch203is in the ‘PBG’, the low-pressure compressor2and3102band102care turned on when the press to test switch204is pushed and, after one minute, these two low-pressure compressors102band102care turned off.

The ‘Full ON’ output is used to turn on the three low-pressure compressors102a,102b, and102cof the low-pressure compressor system102at their maximum operating speed when they are used to inflate the G-suit. This output is high when the G-suit switch260is turned on if no output is required from the mask port. The ‘Mask Port’ output takes precedence over G-suit inflation.

If the ‘Variable Speed Enable’, ‘41 M Speed Enable’, ‘43M Speed Enable’ or ‘45M Speed Enable’ is not turned on, the ‘Normal Speed Enable’ is on (high).

When 41 M is selected, the press to test button204is pushed, and the test select switch203is in the ‘normal’ or ‘PBG’ position, the ‘41 M Speed Enable’ is on (high).

When 43M is selected, the press to test button204is pushed, and the test select switch203is in the ‘normal’ or ‘PBG’ position, the ‘43M Speed Enable’ is on (high).

When 45M is selected, the press to test button204is pushed, and the test select switch203is in the ‘normal’ or ‘PBG’ position, the ‘45M Speed Enable’ is on (high).

When ‘LK-HI’ or ‘LK-LO’ or ‘PBG’ with the press to test button204is pushed, the ‘Variable Speed Enable’ is on provided the G-suit pressure is greater than 55 in H2O. The output from the G-suit pressure transducer (sensor)113is compared with a preset level to determine whether condition is being met.

The high-pressure compressor is turned on by the ‘HP CMPR ON’ signal. The ‘HP CMPR ON’ goes high when the G-suit switch is turned on and the following conditions are met; the G-suit pressure is greater than 55 in H2O but less than 138.4 in H2O, and the G-suit pressure is less than 70 in H2O or ‘LK-GS’ mode selected.

The speed control PCB (PCB3) provides power to the three low-pressure compressors102a,102band102c. The power provided to the low-pressure compressors voltage is variable. This is done to vary the compressors output pressure. The low-pressure compressor1102ais turned off and on independently of the low-pressure compressors2102band3102c. The speed control section outputs one of four fixed voltages or a variable voltage to the compressors that are turned on. Three adjustable voltage regulators tied in parallel supply the compressor voltage. Five external variable resistors set the regulators output voltage. (SeeFIG. 4N)

The speed control PCB (PCB3) has eight logic inputs. The logic inputs set the variable speed control and determine which compressors are turned on. The logic inputs are ‘Full On’, ‘the Low-Pressure Compressor1’, ‘the Low-Pressure Compressor2and3’, ‘Normal Speed Enable’, ‘41M Speed Enable’, ‘43M Speed Enable’, ‘45M Speed Enable’, and ‘Variable Speed Enable’.

The low-pressure compressor motor outputs include four power relays. Two power relays drive the low-pressure compressor1motor and the other two power relays drive the low-pressure compressor2and3motors. Opto isolators drive the power relays. This is done to protect the CMOS logic from inductive spikes that occurs when switching the motors. When the ‘Full On’ input goes high, one set of relays turns on, outputting 15 VDC (voltage of direct current) to all three low-pressure compressor motors102a,102band102c. When either or both of the second set relays turn on, the variable voltage from the voltage regulators is outputted to the appropriate motors. (SeeFIGS. 4M and 4N)

The pressure control262located on the control panel200is the variable resistor that is inputted to the speed control board. It is bypassed when the variable pressure switch290is in the ‘CONST’ position290acausing the mask port pressure to stay at 16 in H2O. Otherwise the output pressure can be varied between 16 and 34 in H2O when the test select switch203is set to ‘PBG’.

As part of preflight, the user verifies his or her communication equipment. The user attaches to the tester and talks into the microphone. The sound picked up by the microphone should be clearly heard with the earphones. Audio system is made up of a preamp and a power amp. Several different kinds of microphones can be inputted into the tester. There are four different microphone inputs. The primary input is ‘audio A’222. This input is configured to accept a 5-ohm dynamic microphone when the audio select switch236is in the LIS/TLK1(listen/talk)236b. In the LIS/TLK2position236c, it is configured to interface with an Electret microphone that requires 10-VDC (voltage of direct current) bias with 8 mA (milliamperes) current limit. In this position an audio input transformer and bias circuit is added to the input circuit. The output of the audio input transformer is fed into the preamp. There are two carbon microphone inputs parallel together. The two inputs are the carbon headset jack226and the PTT (Press to talk) talk jack228. These inputs226and228have 24-VDC bias current limited to 10 mA. The input from the carbon microphone is fed directly to the power amplifier bypassing the preamp. The primary audio output is through the audio A jack222. In the LIS/TLK1236b, it is setup to output into a 10-ohm dynamic microphone. In the LIS/TLK2position236c, it is designed to output to 600 ohm input impedance earphones. The ‘audio B’ jack224is always configured to accept 5 ohm dynamic microphone and output to a 10 ohm dynamic load. The audio A jack222also provides +28 VDC (voltage of direct current) up to 200 mA power. It can be used to drive an ANR (Active Noised Reduction) unit.

A built in continuity tester can be provided to trouble shoot the communication gear. When the audio select switch236is in the ‘cont’ (continuity) position236a, the communication circuits turn into a continuity tester. The carbon microphone, dynamic microphone and dynamic headset output DC resistance is monitored. If the dynamic microphone input resistance is between 4 to 7 ohms, the microphone light230will turn green. If it is less than 2 ohms, the microphone light230will turn red. If the output resistance is between 8 to 12 ohms, the earphone light232will turn green. If the output resistance is less than 2 ohms, the earphone light232will turn red. If the carbon microphone input resistance is between 80 to 500 ohms, the microphone light230will turn green. If it is less than 20 ohms, the microphone light will turn red. The input/output resistance of these three circuits is determined by holding the current through input/output constant. Now the resistance is directly proportional to the voltage. This voltage is amplified and fed into a window comparator and a limit comparator. The window comparators control the microphone/earphone green lights. If the comparators input voltage falls within the upper and lower set points, the green light will turn on. If the input voltage is less than limit comparator set voltage, the red light will turn on.

To perform a goggle test, the EEU-2P flash goggles or equivalent are attached to the tester. After 10 seconds, the PTT button228is pressed. The goggles will turn opaque if they are working. 28 to 32 VDC is supplied to the EEU-2P goggles through the goggle jack238. This voltage has to be 27 VDC min (minimum voltage), when outputting 20 ma into 1400 ohm. The shorted output current must be 70 mA minimum and not more than 100 mA maximum. This is accomplished with voltage regulator and current limiting circuits.

FIG. 5illustrates a general block diagram of a portion of the present invention. The diagram includes a gas system unit802which includes elements such as valve and compressor units and a speed control unit (See PCB3). The gas system unit802is controlled by the main PCB (PCB1) which uses the logic unit804to control the overall operation (SeeFIG. 4). The logic unit804outputs control the speed control unit (See PCB3), and the valves that control the flow. The communication unit806is also included in the present invention and includes the audio unit808(See PCB2) which is connected to PCB1.

The present invention integrates a plurality of testers into one unit and yet requires less power than earlier systems. The unit runs on standard 115 or 230 VAC (voltage of alternating current), 47-440 Hz (hertz), 4 Amperes. Input requirements are 85-132/170-264 VAC 47-440 HZ (hertz) 400 W (watts). The mask port pressure/flow output schedule is shown by the following table:

The tester100can be run from an internal rechargeable battery pack as an alternative to alternating current input from an outside source connected to for example the battery port250. The battery pack can be nickel metal hydride batteries accessible through a weatherproof side panel. Other types of batteries such as lithium-ion and lithium-polymer can also be used. The power cord for outside power source can be attached to the back panel when the console is mounted. A built in charger can charge the tester in one hour or less or 20 minutes on the average. The tester can run up to 8 hours or more from its internal rechargeable battery pack. The duration can be increased depending on the type and size of the battery.

The G-Suit port output pressure is shown by the following table:

An example specification of the present invention (CAST) is described as follows.

The leak indication is shown by a leak above 5.5±0.5 lpm (liters per minute). The flow indication is 0-10,000±25 sccm and 0-300±1 sscm. The pressure drop leak range is 0-5 lpm. The temperature limits for the operating range is 0° C. to 50° C. while for storage is −40° C. to 75° C. The flash goggle power is 28+2 VDC (voltage of direct current), 70-100 ma (milliamperes), current limited to 100 ma (milliamperes) maximum. The active noise reduction (ANR) power is +28±4 VDC (voltage of direct current)200ma (milliamperes) minimum. The microphone input current is 8 mA (milliamperes) maximum at 10 VDC (voltage of direct current).

With this configuration, the present invention can test all the aircrew's life support equipment. The present invention does not require anything more than commonly available local power to operate. The present invention is able to operate in a chemical warfare environment. The present invention does not require a separate high-pressure source of breathing air/oxygen. The present invention significantly reduces supporting man-hours, deployment costs and mobility footprint.