Abstract:
A method of using an aircraft pressurization test apparatus to perform diagnostic tests on an aircraft while the aircraft is at a first region of a ground site, such as an aircraft hanger. The method comprises: positioning the aircraft at the first region of the ground site, using a first delivery line in a manner to enable fluid communication between a shop air aperture of the aircraft pressurization test apparatus and an air coupler of a shop air system at the ground site; using a second delivery line in a manner to enable fluid communication between an aircraft cabin pressurization inlet opening of the aircraft and a delivery air aperture of the aircraft pressurization test apparatus; delivering air from a compressor of the shop air system through the aircraft cabin pressurization inlet opening and into the aircraft cabin via the shop air aperture and the delivery air aperture of the aircraft pressurization test apparatus; and regulating the delivery of air from the compressor of the shop air system through the aircraft cabin pressurization inlet opening by changing characteristics of the flow path between the shop air aperture and the delivery air aperture.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to aircraft pressurization test apparatus and method of using such apparatus to perform pressure-related diagnostic tests on aircraft. 
     A conventional aircraft pressurization test unit includes several measurement components for performing pressure-related diagnostics and an integral blower to pressurize the aircraft cabin. The blower of the test unit is noisy and the noise affects a user&#39;s ability to detect air leaks of the aircraft cabin. Also, the air delivered by the test unit to the aircraft cabin is hot. The hot air makes the aircraft cabin uncomfortably hot for people performing tests in the cabin. 
     SUMMARY OF THE INVENTION 
     Among the several advantages of the present invention may be noted the provision of an improved aircraft pressurization test apparatus which is sufficiently quiet so as to not substantially interfere in a user&#39;s ability to perform pressure-related diagnostics on an aircraft cabin; such an aircraft pressurization test apparatus adapted for delivering cool air to an aircraft cabin; and a method of using an aircraft pressurization test apparatus to perform pressure-related diagnostics on an aircraft cabin which provides improved results. 
     Generally, a method of the present invention is of using an aircraft pressurization test apparatus to perform diagnostic tests on an aircraft while the aircraft is at a first region of a ground site, such as an aircraft hanger. The ground site includes shop air. The shop air comprises a compressor fixedly secured to a second region of the ground site. The shop air further comprises fluid lines and a plurality of air couplers at different locations of the ground site. The compressor and fluid lines are configured and adapted for delivery of pressurized air to the air couplers. The aircraft comprises an aircraft cabin and an aircraft cabin pressurization inlet opening in fluid communication with the aircraft cabin. The aircraft pressurization test apparatus comprises a shop air aperture and a delivery air aperture. The method comprises: positioning the aircraft at the first region of the ground site, using a first delivery line in a manner to enable fluid communication between the shop air aperture of the aircraft pressurization test apparatus and one of the air couplers of the shop air; using a second delivery line in a manner to enable fluid communication between the aircraft cabin pressurization inlet opening and the delivery air aperture; delivering air from the compressor of the shop air through the aircraft cabin pressurization inlet opening and into the aircraft cabin via the shop air aperture and the delivery air aperture of the aircraft pressurization test apparatus; and regulating the delivery of air from the compressor of the shop air through the aircraft cabin pressurization inlet opening by changing characteristics of the flow path between the shop air aperture and the delivery air aperture. 
     Another aspect of the present invention is a method of using an aircraft pressurization test apparatus to detect air leakage from a cabin of an aircraft. The aircraft comprises the aircraft cabin and an aircraft cabin pressurization inlet opening in fluid communication with the aircraft cabin. The aircraft pressurization test apparatus comprises a source air aperture and a delivery air aperture. The method comprises positioning the aircraft at a first region of a ground site. The ground site further includes a second region with a source of pressurized air at the second region. The method further comprises: using a first delivery line in a manner to enable fluid communication between the source air aperture of the aircraft pressurization test apparatus and the source of pressurized air; using a second delivery line in a manner to enable fluid communication between the aircraft cabin pressurization inlet opening and the delivery air aperture; delivering air from the source of pressurized air through the aircraft cabin pressurization inlet opening and into the aircraft cabin via the source air aperture and the delivery air aperture of the aircraft pressurization test apparatus; and listening to the exterior of the aircraft for leakage of air from the aircraft cabin to locate leaks. The delivering of air is sufficient to pressurize the aircraft cabin to a cabin test pressure. The step of positioning the aircraft at the first region of the ground site comprises positioning the aircraft sufficiently remote from the source of pressurized air such that noise from the source of pressurized air is insufficient to interfere with the step of locating leaks. 
     Another aspect of the present invention is a method of using an aircraft pressurization test apparatus to perform diagnostic tests on an aircraft while the aircraft is at a ground site, such as an aircraft hanger. The ground site includes a source of pressurized air. The aircraft comprises an aircraft cabin and an aircraft cabin pressurization inlet opening in fluid communication with the aircraft cabin. The aircraft pressurization test apparatus comprises a source air aperture and a delivery air aperture. The method comprises: positioning the aircraft at the ground site; using a first delivery line in a manner to enable fluid communication between the source air aperture of the aircraft pressurization test apparatus and the source of pressurized air; using a second delivery line in a manner to enable fluid communication between the aircraft cabin pressurization inlet opening and the delivery air aperture; delivering air from the source of pressurized air through the aircraft cabin pressurization inlet opening and into the aircraft cabin via the source air aperture and the delivery air aperture of the aircraft pressurization test apparatus, the delivering of air being sufficient to pressurize the aircraft cabin to a cabin test pressure; detecting leakage of air from the aircraft cabin; and maintaining delivery of air from the source of pressurized air and into the aircraft cabin at a temperature of less than 120° F. (49° C.) during the step of detecting leakage of air from the aircraft cabin. 
     Another aspect of the present invention is an aircraft cabin pressurization test apparatus for performing diagnostic tests on an aircraft while the aircraft is at a first region of a ground site, such as an aircraft hanger. The aircraft comprises an aircraft cabin. The ground site includes a source of pressurized air. The aircraft cabin pressurization test apparatus comprises a housing, a shop air coupler, a delivery air coupler, at least one valve, a supply air flow gauge, a supply air pressure gauge, a cabin feedback air coupler, and a cabin pressure gauge. The shop air coupler is connected to the housing and configured and adapted to releasably receive a fluid line in fluid communication with the source of pressurized air of the ground site. The delivery air coupler is connected to the housing and configured and adapted to releasably receive a fluid line in fluid communication with an aircraft cabin pressurization inlet opening of the aircraft. A supply air pathway is defined between the shop air coupler and the delivery air coupler. The valve is in the supply air pathway and is adapted for controlling flow of air from the shop air coupler through the delivery air coupler. The supply air flow gauge is adapted and configured for gauging air flow in the supply air pathway. The supply air pressure gauge is adapted and configured for gauging air pressure in the supply air pathway. The cabin feedback air coupler is connected to the housing and adapted and configured to releasably receive a fluid line in fluid communication with the aircraft cabin. The cabin pressure gauge is at least partially within the housing and in fluid communication with the cabin feedback air coupler. The cabin pressure gauge is adapted and configured to gauge air pressure in the aircraft cabin when the cabin feedback air coupler is in fluid communication with the aircraft cabin. 
     Other objects and features will be in part apparent and in part pointed out hereinafter. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front elevational view of an aircraft pressurization test apparatus of the present invention; 
     FIG. 2 is a left end elevational view of the aircraft pressurization test apparatus of FIG. 1; 
     FIG. 3 is a right end elevational view of the aircraft pressurization test apparatus of FIG. 1; 
     FIG. 4 is a schematic view of the aircraft pressurization test apparatus of FIG. 1; and 
     FIG. 5 is a schematic view of the aircraft pressurization test apparatus of FIG. 1 connected to a source of pressurized air and connected to an aircraft, the aircraft being shown schematically, fragmented and with portions broken away to show an aircraft cabin. 
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views of the drawings. 
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings and first more particularly to FIGS. 1-4, an aircraft pressurization test apparatus of the present invention is generally indicated by the reference numeral  20 . The aircraft pressurization test apparatus  20  is adapted to perform pressure-related diagnostics on an aircraft cabin. As described in greater detail below, the aircraft pressurization test apparatus  20  may be employed to assist a user in detecting leakage of air from the aircraft cabin. 
     The aircraft pressurization test apparatus  20  comprises a housing  22  (FIGS.  1 - 3 ), a shop air coupler  24  (FIGS. 2 and 4) and a delivery air coupler  26  (FIGS.  3  and  4 ). The shop air coupler  24  is preferably adjacent to and extends out of the housing  22  and includes a shop air aperture  28  (FIG.  2 ). The shop air coupler  24  is preferably a quick-release air coupler and is configured and adapted to releasably receive an air line in fluid communication with a source of pressurized air (discussed in greater detail below). The delivery air coupler  26  is preferably adjacent to and extends out of the housing  22  and includes a delivery air aperture  30  (FIG.  3 ). The delivery air coupler is preferably a quick-release air coupler and is configured and adapted to releasably receive an air line in fluid communication with an aircraft cabin (discussed in greater detail below). The aircraft pressurization test apparatus  20  includes a plurality of components defining a supply air pathway between the shop air aperture  28  and the delivery air aperture  30  for passage of air from the shop air aperture through the delivery air aperture. 
     As shown in FIG. 4, the aircraft pressurization test apparatus  20  further includes a supply air shut-off valve  32 , a shop air pressure gauge  34 , a supply pressure regulator valve  36 , a supply air pressure gauge  38 , a delivery air flow gauge  40 , a flow control shut-off valve  42 , a delivery air temperature gauge  44 , and a delivery air shut-off valve  46 . The supply air shut off valve  32  is preferably a lever-type ball valve adapted and configured to enable a user to quickly shut off air flow through the aircraft pressurization test apparatus  20  and air flow through the supply air pathway. The shop air pressure gauge  34  is configured and adapted for gauging the pressure of incoming air. The supply air regulator  36  regulates supply air pressure to the aircraft cabin. The supply air pressure gauge  38  indicates the pressure of regulated supply air. The delivery air flow gauge  40  is in communication with the delivery air aperture  26  and senses differential pressure along the supply air pathway. The delivery air flow gauge  40  is configured and adapted to gauge air flow through the delivery air aperture  26 . The flow control shut-off valve  42  is preferably a gate valve and is used to check for proper operation of the supply air pressure regulator prior to applying air flow through the delivery air aperture  26  and to the aircraft cabin. The delivery air temperature gauge  44  gauges the temperature of air delivered through the delivery air aperture  26  and to the aircraft cabin. The delivery air temperature gauge  44  may be used for correcting actual air flow data (ACFM) to standard cubic feet per minute (SCFM) values. The delivery air shut off valve  46  is preferably a lever-type ball valve and is configured and adapted to prevent back flow of air through the aircraft pressurization test apparatus  20  when supply air is rapidly shut off by the supply air shut off valve  32 . Preferably, each of the shop air pressure gauge  34 , supply air pressure gauge  38 , delivery air flow gauge  40 , and delivery air temperature gauge  44  is at least partially within the housing  22  but has an externally readable display. Preferably, each of the flow control shut-off valve  42 , delivery air shut-off valve  46 , supply air shut-off valve  32 , and supply pressure regulator valve  36  is partially within the housing but has a portion (e.g., a knob or lever) extending from the housing to operate the valve. 
     The aircraft cabin pressurization test apparatus  20  further comprises a cabin feedback air coupler  50  (FIGS.  3  and  4 ). The cabin feedback air coupler  50  is preferably adjacent to and extends out of the housing  22  and includes a cabin feedback air aperture  52  (FIG.  3 ). The cabin feedback air coupler  50  is preferably a quick-release air coupler and is configured and adapted to releasably receive an air line in fluid communication with an aircraft cabin (discussed in greater detail below). Referring to FIGS. 2 and 4, the aircraft cabin pressurization test apparatus  20  further comprises a cabin pressure gauge  54  and a cabin vertical speed indicator  56 . Preferably, each of the cabin pressure gauge  54  and cabin vertical speed indicator  56  is at least partially within the housing  22  but has an externally readable display. The cabin pressure gauge  54  is in fluid communication with the cabin feedback air aperture  52  and is adapted and configured to gauge air pressure in the aircraft cabin when the cabin feedback air aperture is in fluid communication with the aircraft cabin. The cabin vertical speed indicator  56  is in fluid communication with the cabin feedback air aperture  52  of the cabin feedback air coupler  50  and is adapted and configured for indicating rate of change of air pressure. 
     The aircraft cabin pressurization test apparatus  20  further comprises a door seal output air coupler  60  (FIGS.  3  and  4 ). The door seal output air coupler  60  is preferably adjacent to and extends out of the housing  22  and includes a door seal output air aperture  62  (FIG.  3 ). The door seal output air coupler  60  is preferably a quick-release air coupler and is configured and adapted to releasably receive an air line in fluid communication with a door seal of an aircraft (discussed in greater detail below). A door seal air pathway is defined between the shop air aperture  28  and the door seal pressure output air aperture  62 . The aircraft cabin pressurization test apparatus  20  further includes a door seal regulator valve  64 , a close door seal vent valve  66 , and a door seal pressure gauge  68 . The door seal regulator valve  64  regulates pressure of air supply to an aircraft cabin door seal system. The close door seal vent valve  66  is adapted and configured for venting of the door seal pressure circuit once supply pressure has been turned off. The door seal pressure gauge indicates pressure of air supply to the aircraft cabin door seal system. 
     FIG. 5 is a schematic view of the aircraft pressurization test apparatus  20  connected to an aircraft cabin and connected to a source of pressurized air at a ground site, such as an aircraft hanger. Preferably the source of pressurized air comprises a shop air system, generally indicated at  70 . The shop air system comprises an air compressor  72 , fluid lines  74  and a plurality of air couplers  76  adapted for connection to an air hose. The ground site comprises a first region  80  and a second region  82 . Preferably, the first and second regions  80 ,  82  are separated from each other by at least one wall. Alternatively, the first and second regions  80 ,  82  are in a single room, but are sufficiently remote from one another that noise generated in the first region does not significantly affect hearing-related diagnostics performed in the second region. The first region  80  may constitute a compressor room. The second region  82  is preferably suitable for receive an aircraft, schematically indicated at  84 . Preferably, the air compressor  72  is in the first region  80  of the ground site. Preferably, the aircraft  84  is in the second region of the ground site. Also preferably, the air couplers  76  are at different locations of the ground site. The aircraft  84  comprises an aircraft cabin  86 , an aircraft cabin pressurization inlet opening  88  in fluid communication with the aircraft cabin, an aircraft cabin pressure sense fitting  90  in fluid communication with the aircraft cabin, an aircraft door  92  for providing access to the aircraft cabin, a door seal  94  adjacent the aircraft door and having an interior configured to be inflated, and a door seal inlet opening  96  in fluid communication with the interior of the door seal. 
     In operation, the aircraft cabin pressurization test apparatus  20  is first connected to the source of pressurized air and connected to the airplane  84 . In particular, one end of a first delivery line  100  (e.g., a shop air high pressure hose) is connected to one of the air couplers  76  and the other end of the first delivery line is connected to the shop air coupler  24  to enable fluid communication between the air coupler and the shop air aperture  28 . One end of a second delivery line  102  (e.g., a delivery air supply hose) is connected to the delivery air coupler  26  and the other end of the second delivery line is connected to the aircraft cabin pressurization inlet opening  88  to provide fluid communication between the delivery air aperture  30  and the aircraft cabin  86 . One end of a door seal pressure line  104  is connected to the door seal output air coupler  60  of the aircraft cabin pressurization test apparatus  20  and the other end of the door seal pressure line is connected to the door seal inlet opening  96  to provide fluid communication between the door seal output air aperture  62  and the door seal inlet opening. One end of a cabin feedback sensor hose  106  is connected to the cabin feedback air coupler  50  of the aircraft cabin pressurization test apparatus and the other end is connected to aircraft cabin pressure sense fitting  90  to provide fluid communication between the cabin feedback air aperture  52  and the aircraft cabin  86 . With the fluid lines (hoses) connected and with the supply air shut-off valve  32  closed, the supply pressure regulator valve  36  is closed, the flow control shut-off valve  42  is closed, the door seal regulator valve  64  is closed, and the door seal vent valve  66  is seated to prevent venting. While the shut off valve (not shown) of the shop air system is in a closed position, the supply air shut-off valve  32  is slowly opened and the user verifies that zero pressure is indicated on the shop air pressure gauge  34 . The shut off valve of the shop air system is then slowly opened and the user verifies that pressure is indicated on the shop air pressure gauge  34 . The supply pressure regulator valve  36  is then opened which should cause the pressure indicated by the supply air pressure gauge  38  to increase smoothly. The flow control shut-off valve  42  and the delivery shut-off valve  46  are opened. The foregoing constitutes the equipment set-up procedure. 
     After the equipment set-up procedure is performed, the aircraft cabin pressurization test apparatus  20  may be employed to determine aircraft leakage rates. Aircraft leakage rates may be determined in the following manner. First, the door seal regulator valve  64  is opened until a desired door seal pressure is indicated on the door seal pressure gauge  68 . Opening the door seal regulator valve  64  causes air from the compressor  72  to be delivered through the door seal inlet opening  96  of the aircraft  84  and into the interior of the door seal  94 . The aircraft cabin pressurization test apparatus  20  is then operated to supply pressurized air to the aircraft cabin  86 . The cabin vertical speed indicator  56  is observed to indicate the rate of pressure change of the aircraft cabin. The aircraft&#39;s maintenance manual should be checked to determine the cabin rate of change and pressure limitations. The rate of pressure change is controlled with the supply air pressure regulator valve  36 . The supply air pressure is then slowly increased while the specified rate of pressure change is maintained until the aircraft cabin pressure gauge  54  indicates the preferred cabin test pressure (found in the aircraft maintenance manual). The supply air pressure regulator valve  36  is then slowly moved toward its closed position until the cabin vertical speed indicator  56  indicates zero rate of pressure change and the cabin pressure gauge  54  indicates that the aircraft cabin  86  is held at the preferred cabin test pressure. In an exemplary aircraft, the preferred cabin test pressure is at least 8.0 psig. At this point, the amount of air flow entering the aircraft cabin  86  is equal to the amount of air leaking from the cabin. In other words, the aircraft cabin  86  is in an equilibrium state. With the aircraft cabin  86  in the equilibrium state, the user records the pressure indicated by the supply air pressure gauge  34 , the pressure indicated by the supply air flow gauge  40 , and the temperature indicated by the delivery air temperature gauge  44 . The user then uses the recorded information to convert the actual air flow data to the temperature corrected air flow. 
     With the aircraft cabin  86  maintained in the equilibrium state and with the aircraft cabin held at the preferred cabin test pressure, one or more users may listen to the exterior of the aircraft  84  to determine at least a general region from where the cabin&#39;s air is leaking. Additional detection methods (e.g., applying liquid soap to the general region to see if the air leakage causes the soap to bubble, or burning a cigarette or some other smoke generating element to see if the air leakage blows the smoke) may be employed to pinpoint the source of air leakage. To perform the listening procedure, the first region  80  of the ground site and the air compressor  72  are sufficiently remote from the aircraft such that noise from the air compressor does not interfere with the step of locating leaks. 
     In addition to detecting leaks when the user is outside the aircraft  84 , it is often necessary for the user to be within the aircraft cabin to detect the leaks. Accordingly, it is desirable to keep the aircraft cabin from getting unbearably hot. The air from the compressor  72  is delivered through the aircraft cabin pressurization inlet opening  88  preferably at a temperature of less than 120° F. (49° C.), and more preferably at a temperature of less than 100° F. (38° C.), and even more preferably at a temperature of less than 80° F. (27° C.). 
     A pressure decay method is another method of detecting aircraft leakage rates after the equipment set-up procedure is performed. With the pressure decay method, the aircraft cabin pressurization test apparatus  20  is employed to first pressurize the aircraft cabin to the preferred cabin test pressure. Delivery of air into the aircraft cabin  86  is then preferably abruptly stopped. The user reads and records the cabin pressure gauge  54  at a plurality of time intervals after the stoppage of air delivery into the aircraft cabin  86  to determine air pressure in the aircraft cabin at each such time interval. The cabin pressure decay over time can be plotted on a pressure decay limit graph provided in the aircraft maintenance manual. 
     Thus, the aircraft cabin pressurization test apparatus  20  may be used to perform diagnostics on an aircraft cabin without suffering from the deficiencies of conventional aircraft cabin pressurization test units. 
     In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained. 
     As various changes could be made in the above constructions and methods without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.