Pressure relief door assembly

A pressure relief door (PRD) assembly includes a PRD frame, a PRD coupled to the PRD frame, a latch element configured to remain in a latched condition to maintain the PRD in a closed condition relative to the PRD frame and to assume an unlatched condition to permit the PRD to assume an open condition relative to the PRD frame in accordance with an occurrence of a burst duct event within the PRD frame and a retention element. The retention element is configured to automatically activate responsive to the PRD opening. The retention element includes an end disposable between the PRD and the PRD frame with the retention element automatically activated to provide positive interference to maintain the PRD in the open condition.

BACKGROUND OF THE DISCLOSURE

The subject matter disclosed herein relates to a pressure relief door assembly and, more particularly, to a pressure relief door assembly for burst duct detection.

Modern aircraft, such as commercial jets, include a fuselage that is formed to define a cabin and a cockpit and which has a nose cone section and a tail section, wings extending outwardly from the fuselage and a tail at the tail section of the fuselage. Thrust for the aircraft is generated by engines that are positioned within engine nacelles and typically either attach to the undersides of the wings, or the sides of the fuselage near the rear of the plane, or are built into the tail. The engines include an air inlet, a compressor to compress inlet air, a combustor in which fuel is mixed with compressed inlet air and combusted to produce a working fluid and a turbine in which the working fluid is expanded. The engines further include an outlet through which the working fluid is exhausted to generate the thrust.

The engine nacelles may include an inner fixed structure (IFS), which generally surrounds and provides an aerodynamic fairing for the engine and certain auxiliary devices including ducts that carry fluids to and from the engine sections and auxiliary devices and to the airplane. The engine nacelles further include several structures disposed radially outwardly of the IFS, some of which help define, along with the inner fixed structure, a duct for fan bypass air in a turbofan engine. The IFS may include one or more pressure relief doors.

A failure mode of compressed air ducts associated with the engine can occur when one or more ducts bursts in a “burst duct event.” When this occurs, the pressure relief door will open automatically due to its latch being triggered to relieve overpressure in the compartment formed around the engine by the IFS to prevent structural damage. If a burst duct event does occur, the burst duct event needs to be identified so that appropriate inspections and any necessary repairs can be accomplished.

Currently, burst duct events can be identified by degraded engine performance expressed by the cockpit instruments but, since degraded engine performance expressed by the cockpit instruments does not always lead to identification of the burst duct event, a visual means of detection is often needed as a primary detection means or as a backup means. Often, a burst duct event can be detected through a visual inspection of the nacelle and the pressure relief door by identifying that the pressure relief door has unlatched and opened. However, due to the location of some pressure relief doors generally being on the upper hemisphere of the engine nacelle, if a burst duct event occurs and the pressure relief door opens during flight, the pressure relief door may return to or close to its original position due to gravity, and therefore not allow for the burst duct event to be detected from an inspection of the pressure relief door.

BRIEF DESCRIPTION OF THE DISCLOSURE

According to one aspect of the disclosure, a pressure relief door (PRD) assembly is provided and includes a PRD frame, a PRD hinge-coupled to the PRD frame, a latch element configured to normally remain in a latched condition to maintain the PRD in a closed condition relative to the PRD frame and to assume an unlatched condition to permit the PRD to assume an open condition relative to the PRD frame in accordance with an occurrence of a burst duct event within the PRD frame and a retention element. The retention element is configured to automatically activate responsive to the PRD opening. The retention element includes an end disposable between the PRD and the PRD frame with the retention element automatically activated to provide positive interference directed to maintain the PRD in the open condition.

In accordance with additional or alternative embodiments, the retention element includes a first frame element affixed to the PRD, a second frame element affixed to the PRD frame and an elastic element. The elastic element is coupled to one of the first and second frame elements such that the end is elastically biased against the other of the first and second frame elements in a non-interfering position with the PRD in the closed condition and disposable in an interference position between the PRD and the PRD frame with the PRD in the open condition.

In accordance with additional or alternative embodiments, the first and second frame elements are misaligned.

In accordance with additional or alternative embodiments, the first and second frame elements include L-shaped brackets.

In accordance with additional or alternative embodiments, the elastic element includes a leaf spring.

In accordance with additional or alternative embodiments, the elastic element includes bent flanges extending along a portion of the end.

According to another aspect of the disclosure, a pressure relief door (PRD) assembly is provided and includes a PRD frame, a PRD hinge-coupled to the PRD frame, a latch element configured to normally remain in a latched condition to maintain the PRD in a closed condition relative to the PRD frame and to assume an unlatched condition to permit the PRD to assume an open condition relative to the PRD frame in accordance with an occurrence of a burst duct event within the PRD frame, frame elements affixed to the PRD and the PRD frame and an elastic element. The elastic element is coupled to one of the frame elements to be elastically biased against the other of the frame elements in a non-interfering position with the PRD in the closed condition and disposable in an interference position between the PRD and the PRD frame with the PRD in the open condition.

In accordance with additional or alternative embodiments, the first and second frame elements are misaligned.

In accordance with additional or alternative embodiments, the first and second frame elements include L-shaped brackets.

In accordance with additional or alternative embodiments, the elastic element includes a leaf spring.

In accordance with additional or alternative embodiments, the elastic element includes bent flanges.

DETAILED DESCRIPTION OF THE DISCLOSURE

As will be described below, a pressure relief door (PRD) assembly is provided for use with an engine nacelle of an aircraft or another suitable vehicle. The PRD assembly allows for a detection of a burst duct by maintaining the PRD in an open position after a burst duct event, until the PRD is reset and closed by a maintenance worker.

With reference toFIG. 1, an aircraft1is provided. The aircraft1includes a fuselage2, which has an aerodynamic nose cone and a trailing portion opposite the nose cone, wings3extending outwardly from the fuselage2, a tail portion4at the trailing portion of the fuselage2and engines5. The engines5are supported under the wings3and within engine nacelles6. Other engine mounting locations for the engines5include the rear side of the fuselage2. Alternatively, the engines5can be built into the tail portion4.

With continued reference toFIG. 1and with additional reference toFIGS. 2 and 3, the engine nacelles6each include an engine assembly60, an inner fixed structure (IFS)61and an outer fixed structure (OFS)62that surrounds the IFS61. For each engine nacelle6, the IFS61forms an aerodynamic fairing around and provides a PRD frame for the engine assembly60and multiple compressed air ducts601associated with the engine assembly60, along with several other auxiliary components, tubes, wire harnesses, etc.

The OFS62is disposed to surround the IFS61and may be provided as a generally annular element with an aerodynamic taper that narrows toward the trailing end of the engine nacelle6. The IFS61includes an engine PRD frame610, a PRD611that is hinge-coupled to the engine PRD frame610and a latch element612. The engine PRD frame610can serve as a frame for the PRD611that attaches to the IFS61(i.e., a housing) or, in some cases, the PRD611can include a door and a hinge that attaches directly to the IFS61. The latch element612may include a spring-loading613(seeFIG. 3) and is configured to normally remain in a latched condition to thereby maintain the PRD611in a closed condition. However, the latch element612may also assume an unlatched condition to thereby permit the PRD611to assume an open condition in accordance with an occurrence of a burst duct event in any one or more of the multiple ducts601to relieve excess pressures.

As shown inFIGS. 2-4, the PRD611is disposed in an upper hemisphere of the engine PRD frame610. As such, if a burst duct event occurs at some point during the operation of the engine5or at some other point, the force of gravity will act upon the PRD611and cause the PRD611to tend to “fall” toward the latched condition, which would make detection of the burst duct event difficult during a normal inspection of the engine5and the engine nacelle6. In fact, even if the PRD611remains open a little bit, it may be difficult for an operator to see because the PRD611is located on top of the IFS61(and inside of a dark duct), so a more obviously open PRD611would be helpful. To this end, each engine nacelle6further includes a PRD assembly10(seeFIG. 4). The PRD assembly10includes a PRD retention element20. The PRD retention element20is configured to automatically activate in an event the PRD611opens and is further configured to provide positive interference in a manner directed to maintain the PRD611in the open condition.

In accordance with embodiments, a single- or multiple-part hinge614may be provided proximate to a leading edge6110of the PRD611to thereby couple the PRD611to the engine PRD frame610such that the PRD611can pivot in an open condition about a hinge axis close to the leading edge6110. Also, the latch element612may be disposed at a trailing edge6111of the PRD611and the PRD retention element20may be disposed at a lateral edge6112of the PRD611. However, it is to be understood that this is not required and that other configurations are possible. These other configurations may include, but are not limited to, the latch element612and the PRD retention element20being disposed at other edges of the PRD611or the latch element612and the PRD retention element20being incorporated into a same device (e.g., a latch and retention element). With the above in mind, however, and for the purposes of clarity and brevity, the following description will only relate embodiments in which the latch element612and the PRD retention element20are disposed at the trailing and lateral edges6111and6112, respectively.

With continued reference toFIG. 4and with additional reference toFIGS. 5 and 6, the PRD retention element20includes a first frame element30, a second frame element40and an elastic element50. The first frame element30is affixed to the PRD611and may be provided as an L-shaped bracket31with a first leg310that is fastened to a surface of the PRD611and a second leg311that protrudes away from a plane of the surface of the PRD611. The second frame element40is affixed to the engine PRD frame610and may be provided as an L-shaped bracket41with a first leg410that is fastened to a surface of the engine PRD frame610and a second leg411that protrudes away from a plane of the surface of the engine PRD frame610.

In accordance with embodiments, the respective surfaces of the PRD611and the engine PRD frame610may be substantially parallel such that the respective first legs310,410of the first and second frame elements30and40are disposable at a similar plane with the PRD611in the closed condition. The respective second legs311,411of the first and second frame elements30and40may be, but need not be, disposed in parallel with one another. In some embodiments, the second leg411of the second frame element40may be at least partially superimposed over a portion of the PRD611.

In accordance with further embodiments, the first frame30and the second frame40may be axially misaligned with respect to one another and, with such a misaligned configuration, the elastic element50may be provided as a leaf spring501that is substantially as wide as the height of the respective second legs311,411of the first and second frame elements30and40. The elastic element50has a first end51and a second end52. The elastic element50is coupled to one of the first and second frame elements30and40at the first end51such that the second end52extends distally toward the other of the first and second frame elements30and40(for purposes of clarity and brevity, the following description will relate to the case in which the first end51is coupled to the second leg311of the first frame element30and that the second end52extends distally toward the second frame element40). The second end52includes bent flanges521on either lateral side thereof and further includes generally continuous first and second curves522,523that provide the elastic element with a predefined elasticity.

The second end52is thus elastically biased against the second leg411of the second frame element40in a non-PRD-interfering position with the PRD611in the closed condition (seeFIG. 5). Here, it is noted that since at least the second leg411of the second frame element40is superimposed over the portion of the PRD611, the second end52is maintained in a superimposed position over the PRD611and in a non-superimposed position with respect to the engine PRD frame610and thus does not impede movement of the PRD611from the closed condition to the open position during a burst duct event.

By contrast, the second end52is disposable in a PRD-interference position between the PRD611and the engine PRD frame610with the PRD611in the open condition. That is, once the PRD611moves into the open condition, the second end52passes away from the second leg411and is no longer prevented from elastically extending into the PRD interference position between the PRD611and the engine PRD frame610(seeFIG. 6). In this position, the bent flanges521impinge against the interior surface of the PRD611and the outer surface of the engine PRD frame610.

In accordance with alternative embodiments and, with reference toFIG. 7, the first and second frame elements30and40may be axially aligned with respect to one another. In this case, the elastic element50may be provided as a compression spring502that extends along a substantially straight line in the closed and open conditions.