Aeronautics and astronautics – Aircraft structure – Details
Reexamination Certificate
1999-05-04
2001-05-08
Barefoot, Galen L. (Department: 3644)
Aeronautics and astronautics
Aircraft structure
Details
C004S321000, C244S118500
Reexamination Certificate
active
06227490
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to the field of the prevention of lavatory fluid leakage in connection with aircraft in flight where blue ice forms on aircraft surfaces.
2. Description of Prior Art
Aircraft that contain in-flight lavatory systems usually experience what is known as a “blue icing” condition. When the aircraft is in flight, air inside the aircraft is pressurized. At high altitudes, the outside air pressure is much lower and the air temperature is much colder than the inside air pressure and temperature of the aircraft causing a pressure differential and a temperature gradient. Any water that is disposed on the aircraft skin, whether if be from atmospheric accumulation or from leakage from inside the aircraft immediately freezes and accumulates in a mass on the aircraft skin.
Aircraft with lavatories contain a lavatory fluid reservoir which serves as the depository for all lavatory fluid and waste going to and from the lavatory or lavatories of the aircraft. A disposal hose connects from the lavatory fluid reservoir to a service valve located near the service door of the aircraft. When the aircraft has landed, the lavatory fluid and waste in the lavatory fluid reservoir can be removed from the reservoir by a suction hose of a service truck which is connected by ground crews to the service valve. In flight, the service valve along with the service door are shut and sealed.
Despite the service valve and service door being shut during flight, and despite the attempt to provide leak-proof seals, the differential in air pressure once the aircraft is in flight causes lavatory fluid to leak out of the service valve and pool around the inside base of the service door. The constant expansion and contraction of the aircraft and all of its parts with each take off and landing cycle due both to temperature and pressure cycling makes the retention of a leak-proof seal at the service valve and door impossible. The repeated rough handling of the service valve and door and their seals by repeated access by the ground crew also contributes to the comprise of the seal integrity. Sooner or later the occurrence of a leak of the lavatory fluid through the seal of the service valve and door will occur.
The fluid then leaks through the service valve and eventually through the service door. After leaking through the seal on the service door to the outer surface of the aircraft near the lower edge of the service door, a blue ice chunk or frozen solid mass of lavatory fluid results because of the cold outside air temperatures. The name “blue icing” comes from the fact that the frozen lavatory fluid has an additive for odor and sanitation, which is usually blue in color.
Blue ice has fallen from aircraft to the ground and unto homes, causing severe damage to structures and automobiles which have been hit and putting persons at jeopardy to injury. Even more often, depending in part on the proximity of the service door to the engine intakes, blue ice can and has entered jet engines resulting in engine failures and in some cases the destruction and physical detachment of the entire engine from the aircraft, not only jeopardizing land-based property and life, but also airborne property and life.
Therefore, what is needed is an apparatus and a method by which lavatory fluid can be prevented from leaking through the service door and, eventually, becoming blue ice.
BRIEF SUMMARY OF THE INVENTION
The invention is an apparatus and a method for preventing aircraft lavatory fluid from leaking out of the service door during flight and, consequently, becoming frozen on the outer surface of the aircraft.
The invention is an apparatus of interconnected devices working together to collect aircraft lavatory fluid leaking or escaping out from the service valve during flight and returning the lavatory fluid back for use, thus preventing any aircraft lavatory fluid from pooling around the inside base of the service door.
The system comprises a sump placed directly beneath the service valve. The pump comprises a container with an open top face and inner walls, such as a scupper pan, and a removable screen cover, which serves as a lid to the container. The removable screen cover, which is attached to the top of the container by quick-release latches, serves to filter out debris and solid matter from the lavatory fluid leaking from the service valve.
Inside the sump is a pump. The pump is attached to a bottom side of the removable screen cover. The pump need not be attached to the removable screen cover or to any particular part of the pump as long as the pump is located within the pump. The pump is powered via a power line that passes through the wall of the container. The pump may be any type of pump. Attached on an inner wall of the container near the top is a level sensor switch. The level sensor switch senses the level of the lavatory fluid in the container. Once the level rises to a predetermined level, the level sensor switch activates the pump.
The scope of the invention also encompasses any type of sensor, such as a weight sensor, which will activate the pump once the sump contains a predetermined amount of aircraft lavatory fluid.
The pump then pushes the lavatory fluid through a recirculation loop. The recirculation loop comprises a hose in circuit with a one-way valve to prevent back flow of the lavatory fluid. Attached on the opposite end of the recirculation loop is a fluid return fitting, shaped like a “T”, which has three ports, a top port, a middle port and a bottom port. Each of the top, bottom and middle ports of the fitting communicates with each other. The middle port connects to the recirculation hose. The bottom port of the fluid return valve connects to the lavatory fluid reservoir, allowing the lavatory fluid from the recirculation loop to return to the lavatory fluid reservoir. The top port of the fluid return valve connects to a vent hose that allows air pressure within the lavatory fluid reservoir to be equalized with the air pressure of the rest of the aircraft.
The system also comprises a splash shield which is located directly outside the service valve between the service valve and the service door. Once the aircraft has landed and the service valve is accessed by a service ground crew, the splash shield serves to catch any fluid or solid waste spilling out of the service valve and directs the spill fluids and solid wastes back into the sump to where it drains. In the event that lavatory fluid is forcefully squirted through the service valve, the splash shield also serves to direct the fluid from the service door and direct it toward the pump to where it drains.
Therefore, in summary it can be appreciated that the invention is an apparatus for collecting and returning aircraft lavatory fluid leaked from a service valve in an aircraft while in flight comprising a pump for collecting aircraft lavatory fluid leaked from the service valve; a lavatory fluid reservoir communicating with the service valve; and a pump located inside the sump, the pump being communicated to the lavatory fluid reservoir to return the aircraft lavatory fluid to the lavatory fluid reservoir.
The invention can also be characterized as a method for preventing leakage of aircraft lavatory fluid from a service valve through a service door in an aircraft while in flight and preventing formation of blue ice on the outer surface of the aircraft in flight comprising the steps of providing a reservoir of aircraft lavatory fluid; collecting the aircraft lavatory fluid leaked from the service valve; and transporting the collected aircraft lavatory fluid to the lavatory fluid reservoir.
The invention now having been briefly summarized, it may be better visualized by turning to the following drawings wherein like elements are reference by like numerals.
REFERENCES:
patent: 4070714 (1978-01-01), Bishton, Jr. et al.
patent: 4114203 (1978-09-01), Carolan
patent: 4787772 (1988-11-01), Wagner
patent: 5115520 (1992-05-01), Colebrook et al.
patent: 5372710 (1994-12-01), Frank
patent:
Barefoot Galen L.
Dawes, Esq. Daniel L.
Myers Dawes & Andras LLP
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