Relief of inter-compartment differential pressure in aircraft

#This invention relates to improved aircraft safety equipment, for preventing damage to an aircraft upon sudden depressurization of one of several pressurized compartments while in flight.

#A recent major aircraft crash in which many lives were lost was caused by accidental opening and loss in flight of a door to the cargo compartment of a wide-bodied jet aircraft. When this door opened, the sudden depressurization of the cargo compartment resulted in the development of such a high differential pressure between that compartment and a passenger compartment thereabove that the deck of the passenger compartment was deformed downwardly in a manner damaging control cables located beneath that deck. This caused complete loss of control of the aircraft, which then crashed. Similar difficulties might in some instances occur as a result of differential pressure induced deformation of a vertical bulkhead between two initially pressurized compartments if one of those compartments loses pressure in flight. For example, on a wide-bodied jet, depressurization of the cargo compartment on the lower level of the craft might cause bulging of the bulkhead between that compartment and a galley on the same level.

#The present invention provides a novel safety arrangement for preventing such deformation of an inter-compartment wall in an aircraft upon loss of pressure in a compartment at one side of the wall. In this connection, the term "wall" as used in the present application is intended to be interpreted broadly as including any type of wall structure separating two compartments, regardless of the direction in which the wall may extend, and in particular including both horizontal deck structures and vertical bulkheads.

#The above and other features and object of the invention will be better understood from the following detailed description of the typical embodiments illustrated in the accompanying drawings in which:

#FIG. 1 is a diagrammatic representation of an aircraft having walls containing pressure relief panels in accordance with the teachings of the present invention;

#FIG. 2 is an enlarged section through one of the frangible panel assemblies of FIG. 1, and typically taken on the line 2--2 of FIG. 1;

#Referring to FIG. 1; there is illustrated at 10 an aircraft having a fuselage 11 which is divided interiorly into a number of separate compartments, including an upper passenger compartment 12, a lower cargo compartment 13, and a galley 14 on the same level as the cargo compartment. A horizontal deck 15 defines the floor of passenger compartment 12, and the ceiling of the other two compartments 13 and 14, with a vertical bulkhead 16 extending between and separating the two lower level compartments 13 and 14. When the aircraft is on the ground, access is provided to each of the compartments through doors, hatch covers, or the like, including in the case of the cargo compartment 13 a door or hatch cover represented diagrammatically at 17. All of the compartments within the craft are pressurized in flight to a value substantially higher than the ambient pressure surrounding the plane at high elevation. The pressurizing equipment is diagrammatically represented in FIG. 1 at 18. Normally, this equipment maintains essentially the same pressure in the lower compartments 13 and 14 as in the upper compartment 12.

#For equalizing the pressure above and beneath deck 15, and at opposite sides of bulkhead 16, in the event of accidental depressurization of one of the compartments, the deck 15 and bulkhead 16 both contain a number of typically rectangular openings 19 of substantial size, with each of which there is associated one of a number of pressure relief units 20. One of these pressure relief units 20 is illustrated in FIG. 2, being represented in that figure as connected into the vertical bulkhead 16, though it is to be understood that the showing of FIG. 2 can also be considered as representing a cross section through one of the pressure relief units in deck 15.

#In FIG. 2, there is connected into the rectangular opening 19 in wall 16 a correspondingly rectangular frangible closure panel 21 which may take the form of a flat plate of a material which is extremely brittle and adapted to shatter into many pieces when impacted by a mechanical striker 22 in a manner which is to be described at a later point. Any suitable material capable of shattering in this manner may be employed, such as a highly tempered glass, frangible expanded rigid polyurethane, expanded polystyrene, acrylic sheet material, or the like. At the same time, however, the panel 21 should have sufficient thickness and strength to maintain its integrity effectively under such vibrational and other forces as occur in flight and in normal maintenance and operation of the aircraft.