GB1559663A

GB1559663A - Safety arrangements for casing parts of an aircraft jet propulsion engine

Info

Publication number: GB1559663A
Application number: GB462778A
Authority: GB
Original assignee: Societe Nationale dEtude et de Construction de Moteurs dAviation SNECMA; SNECMA SAS
Current assignee: Safran Aircraft Engines SAS
Priority date: 1977-02-08
Filing date: 1978-02-06
Publication date: 1980-01-23
Also published as: FR2379433A1; FR2379433B1

Description

(54) IMPROVEMENTS IN OR RELATING TO SAFETY ARRANGEMENTS FOR CASING PARTS OF AN AIRCRAFT JET PROPULSION ENGINE (71) We, SOCIETE NATIONALE D'ETUDE ET DE CONSTRUCTION DE MOTEURS D'AVIA TION, of 2 boulevard Victor, 75015, Paris, France, a French Body Corporate, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This inventon relates to a safety arrangement for use in connecting together various casing parts of an aircraft jet propulsion engine.

According to the present invention there is provided a safety arrangement for incorporation in the casing of an aircraft jet propulsion engine including an air intake fairing secured to a first annular flange of the casing, a jet nozzle housing secured to a second annular flange of the casing, an intermediate housing formed as two hinged parts enclosing the space lying between the first and the second annular flanges, and connecting means serving, when the intermediate housing is in its operative configuration, to provide a connection between the intermediate housing and the air intake fairing and the jet nozzle housing respectively.

Further according to the present invention there is provided a safety arrangement for installation on a double flow type of aircraft jet propulsion engine with a front fan bounded by a fan casing comprising an air intake fairing secured to an upstream flange of the fan casing, a jet nozzle housing secured to a downstream flange of the fan casing, an intermediate housing of two hinged parts enclosing the said fan casing, and connecting means serving, when the intermediate housing is closed to connect the latter respectively with the air intake fairing and the nozzle housing.

Still further according to the present invention there is provided an aircraft jet propulsion enRine comprising a casing assembly including an air intake fairing. a jet nozzle housing and an intermediate housing between the fairing and the jet nozzle housing, first connection means operative between the fairing and a fan casing within the intermediate housing and between the fan casing and the jet nozzle housing, and supplementary connection means operative when the assembly is closed to hold the intermediate housing connected to the intake fairing and the jet nozzle housing.

Yet further according to the present invention there is provided an aircraft jet propulsion engine incorporating a front fan and comprising means for supporting the engine from pylon or strut means of an aircraft, a casing assembly for enclosing the component parts of the engine, said casing assembly including an air intake fairing having an annular flange at its downstream end, a fan casing enclosing the front fan having an annular flange at its upstream end and an annular flange at its downstream end, a jet nozzle housing having an annular flange at its upstream end connected to the downstream flange of the fan casing, a two part annular intermediate housing, each part being of semi-annular section and being hinged together, the intermediate housing being connected, when the housing is closed, to the intake fairing and the jet nozzle by respective profiled members rigid with the intermediate housing which engage in complementary recess defining members of the intake fairing and the jet nozzle housing, the profiles being of V-section and extending peripherally of the respective intermediate housing, intake fairing and nozzle housing.

An embodiment of a safety arrangement in accordance with the invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings, in which: Figure 1 is a longitudinal section of an installation in a nacelle of a double flow jet propulsion engine incorporating an emembodiment of a safety arrangement in accordance with the invention; Figure 2 is a cross-section on the line A-A of Figure 1; and Figure 3 shows, to an enlarged scale, a part B of Figure 1 including the safety arrangement.

Referring to Figure 1, a double flow jet propulsion engine with a front fan 2 is mounted on "pylon" or "strut" means of an aircraft 2 by connecting devices 3, and 4 secured respectively to the fan casing 5 and a primary casing 6.

The nacelle in which the engine 1 is located comprises three parts which are successively considered in the direction of flow, an air intake fairing 7, an intermediate housing 8 forming a fan compartment and a jet nozzle housing 9. Connecting means 10 secure a flange 1 1a of the air intake fairing to an annular upstream flange 1 1b of the fan casing 5. Similarly, connecting means 12 secure a flange 13a at the upstream end of the nozzle housing to an annular downstream flange 13b of the fan casing 5. The connecting means 10 and 12 may be constituted, for example, by bolts.

The arrangement of the intermediate housing 8 will be better understood by referring to Figure 2 which is a cross-section on the line A-A of Figure 1. The intermediate housing 8 surrounding the fan compartment comprises two parts 8a and 8b of semi-annular section respectively hinged together by means of hinges 14a and 14b mounted on the connecting device 3 of the fan casing 5, in turn connected to the "pylon" or "strut" of the aircraft 2. The closure of the intermediate housing 8 is effected by means of a rapid attachment system 15 of any known type.

It will be noted, in Figure 1, that if no special precautions are taken, failure at the zone of the connecting means 10 and 12 may have serious or catastrophic consequences leading even to the loss in flight, either of the air intake fairing 7 or of the nozzle housing 9. Such a failure may be caused by the connecting means 10 and 12 themselves but also by the flanges 1 la and 13a respectively of the air intake fairing and of the nozzle housing or the flanges llb and 13b of the fan casing 5 which may have cracks and fractures at an inopportune moment.

In order to overcome this disadvantage, the invention provides a safety system constituted by secondary connection means between the air intake fairing 7 and the nozzle housing 9, such "supplementary" connection ensuring maintenance in a correct position of the air intake fairing and the nozzle housing if the first connecting means fails. This supplementary connection is effected by the intermediate housing 8 when the latter is closed. The means which provide this supplementary connection are illustrated in detail in Figure 3 which shows, to a much enlarged scale, the part B of Figure 1.The description which follows, with regard to Figure 3 concerns the connecting means between the upstream edge of the nozzle housing 9 and the downstream edge of the intermediate housing 8, it being understood that a description and an exactly corresponding Figure may be made for the connection between the downstream edge of the air intake fairing 7 and the upstream edge of the intermediate housing 8.

The downstream edge of the central housing 8 carries a profiled member 16 which is inwardly directed when the intermediate housing is closed, and a member 17 defining a complementary recess directed outwardly and formed at the periphery of the upstream edge of the nozzle housing 9. Both members 16 and 17 are semi-annular.

In the form illustrated, which enables simultaneous achievement of a convenient and good connection, the profiled member 16 has a section in the form of a "V", the point being directed inwardly, the complementary recess-defining member 17 also having a section of "V" form, but opening outwardly.

It will be readily understood that by connecting the two parts 8a and 8b of the intermediate housing 8, by means of the attachment system 15, the engagement of the profiled members 16 in the recessed members 17 is effected with a pressure such, that in the case of a rupture of the connecting - means 10 and 12, the air intake fairing 7 and the nozzle housing 9 cannot become disengaged from the intermediate housing 8. The arrangement in accordance with the invention thus represents appreciable improvement in security in flight.

In a preferred embodiment and with a view to avoiding introduction into the casing 5, into the air intake fairing 7, into the nozzle housing 9, into the intermediate housing 8 and into the connecting means, of excessive stresses, the profiled members 16 and the complementary recess-defining members 17 are not in metal-to-metal contact but when the housings 8a and 8b are in their operative positions they are separated by a resilient member 18 enabling the absorption of manufacturing tolerances and deformations of different parts. It is also possible to omit this resilient member and to leave a sufficient clearance with the same objective of avoiding the introduction of high forces resulting from direct tight contact.

WHAT WE CLAIM IS: 1. A safety arrangement for incorporation in the casing of an aircraft jet pro

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. Figure 2 is a cross-section on the line A-A of Figure 1; and Figure 3 shows, to an enlarged scale, a part B of Figure 1 including the safety arrangement. Referring to Figure 1, a double flow jet propulsion engine with a front fan 2 is mounted on "pylon" or "strut" means of an aircraft 2 by connecting devices 3, and 4 secured respectively to the fan casing 5 and a primary casing 6. The nacelle in which the engine 1 is located comprises three parts which are successively considered in the direction of flow, an air intake fairing 7, an intermediate housing 8 forming a fan compartment and a jet nozzle housing 9. Connecting means 10 secure a flange 1 1a of the air intake fairing to an annular upstream flange 1 1b of the fan casing 5. Similarly, connecting means 12 secure a flange 13a at the upstream end of the nozzle housing to an annular downstream flange 13b of the fan casing 5. The connecting means 10 and 12 may be constituted, for example, by bolts. The arrangement of the intermediate housing 8 will be better understood by referring to Figure 2 which is a cross-section on the line A-A of Figure 1. The intermediate housing 8 surrounding the fan compartment comprises two parts 8a and 8b of semi-annular section respectively hinged together by means of hinges 14a and 14b mounted on the connecting device 3 of the fan casing 5, in turn connected to the "pylon" or "strut" of the aircraft 2. The closure of the intermediate housing 8 is effected by means of a rapid attachment system 15 of any known type. It will be noted, in Figure 1, that if no special precautions are taken, failure at the zone of the connecting means 10 and 12 may have serious or catastrophic consequences leading even to the loss in flight, either of the air intake fairing 7 or of the nozzle housing 9. Such a failure may be caused by the connecting means 10 and 12 themselves but also by the flanges 1 la and 13a respectively of the air intake fairing and of the nozzle housing or the flanges llb and 13b of the fan casing 5 which may have cracks and fractures at an inopportune moment. In order to overcome this disadvantage, the invention provides a safety system constituted by secondary connection means between the air intake fairing 7 and the nozzle housing 9, such "supplementary" connection ensuring maintenance in a correct position of the air intake fairing and the nozzle housing if the first connecting means fails. This supplementary connection is effected by the intermediate housing 8 when the latter is closed. The means which provide this supplementary connection are illustrated in detail in Figure 3 which shows, to a much enlarged scale, the part B of Figure 1.The description which follows, with regard to Figure 3 concerns the connecting means between the upstream edge of the nozzle housing 9 and the downstream edge of the intermediate housing 8, it being understood that a description and an exactly corresponding Figure may be made for the connection between the downstream edge of the air intake fairing 7 and the upstream edge of the intermediate housing 8. The downstream edge of the central housing 8 carries a profiled member 16 which is inwardly directed when the intermediate housing is closed, and a member 17 defining a complementary recess directed outwardly and formed at the periphery of the upstream edge of the nozzle housing 9. Both members 16 and 17 are semi-annular. In the form illustrated, which enables simultaneous achievement of a convenient and good connection, the profiled member 16 has a section in the form of a "V", the point being directed inwardly, the complementary recess-defining member 17 also having a section of "V" form, but opening outwardly. It will be readily understood that by connecting the two parts 8a and 8b of the intermediate housing 8, by means of the attachment system 15, the engagement of the profiled members 16 in the recessed members 17 is effected with a pressure such, that in the case of a rupture of the connecting - means 10 and 12, the air intake fairing 7 and the nozzle housing 9 cannot become disengaged from the intermediate housing 8. The arrangement in accordance with the invention thus represents appreciable improvement in security in flight. In a preferred embodiment and with a view to avoiding introduction into the casing 5, into the air intake fairing 7, into the nozzle housing 9, into the intermediate housing 8 and into the connecting means, of excessive stresses, the profiled members 16 and the complementary recess-defining members 17 are not in metal-to-metal contact but when the housings 8a and 8b are in their operative positions they are separated by a resilient member 18 enabling the absorption of manufacturing tolerances and deformations of different parts. It is also possible to omit this resilient member and to leave a sufficient clearance with the same objective of avoiding the introduction of high forces resulting from direct tight contact. WHAT WE CLAIM IS:

1. A safety arrangement for incorporation in the casing of an aircraft jet pro

pulsion engine including an air intake fairing secured to a first annular flange of the casing, a jet nozzle housing secured to a second annular flange of the casing, an intermediate housing formed as two hinged parts enclosing the space lying between the first and second annular flanges, and connecting means serving, when the intermediate housing is in its operative configuration, to provide a connection between the intermediate housing and the air intake fairing and the jet nozzle housing respectively.

2. A safety arrangement for installation on a double flow type of aircraft jet propulsion engine with a front fan bounded by a fan casing comprising an air intake fairing secured to an upstream flange of the fan casing, a jet nozzle housing secured to a downstream flange of the casing, an intermediate housing of two hinged parts enclosing the fan casing, and connecting means serving, when the intermediate housing is closed to connect the latter respectively with the air intake fairing and the nozzle housing.

3. A safety arrangement according to claim 1 or claim 2 wherein the connection of the intermediate housing with the air intake fairing and the jet nozzle housing is effected by profile means, directed inwardly and disposed at the upstream and downstream peripheries of the intermediate housing, the said profile means being engaged, when the intermediate housing is closed, in complementary recesses, directed outwardly and formed respectively in the periphery of the downstream edge of the air intake respectively in the periphery of air intake fairing and the periphery of the upstream edge of the jet nozzle housing.

4. A safety arrangement according to claim 1 or claim 2, wherein the connection of the intermediate housing with the air intake fairing and the jet nozzle housing is effected by profile means, directed inwardly and disposed at the upstream and downstream peripheries of the intermediate housing, the said profile means co-operating, through the intermediary of resilient members, when the intermediate housing is closed with complementary recesses directed outwardly, and formed respectively in the downstream peripheral edge of the air intake fairing and the upstream edge of the periphery of the jet nozzle housing.

5. A safety arrangement according to claim 1 or claim 2, wherein the connection of the intermediate housing with the air intake fairing and the jet nozzle housing is effected by profile means, directed inwardly and disposed at the upstream and downstream peripheries of the intermediate hous incur, the said profiles co-operating, whilst leaving a reduced clearance, when the intermediate housing is closed, with complementary recesses, directed outwardly and formed respectively in the downstream periphery of the air intake fairing and the upstream peripheral edge of the jet nozzle housing.

6. 'claims A safety arrangement according to one of claims 3 to 5, wherein the profiles disposed on the intermediate housing have a 'V' section, the point being directed inwardly, the complementary recesses both in the air intake fairing and the jet nozzle housing then having a 'V' section with the opening directed outwardly.

7. An aircraft jet propulsion engine comprising a casing assembly including an air intake fairing, a jet nozzle housing and an intermediate housing between the fairing and the jet nozzle housing, first connection means operative between the fairing and a fan casing within the intermediate housing and between the fan casing and the jet nozzle housing, and supplementary connection means operative when the assembly is closed to hold the intermediate housing connected to the intake fairing and the jet nozzle housing.

8. An aircraft jet propulsion engine incorporating a front fan and comprising means for supporting the engine from pylon or strut means of an aircraft, a casing assembly for enclosing the component parts of the engine, said casing assembly including an air intake fairing having an annular flange at its downstream end, a fan casing enclosing the front fan having an annular flange at its upstream end and an annular flange at its downstream end, a jet nozzle housing having an annular flange at its upstream end connected to the downstream flange of the fan casing, a two-part, annular, intermediate housing, each part being of semi-annular section and being hinged together, the intermediate housing being connected, when the housing is closed, to the intake fairing and the jet nozzle housing by respective profiled members rigid with the intermediate housing which engage in complementary recess defining members of the intake fairing and the jet nozzle housing, the profiles being of V-section and extending peripherally of the respective intermediate housing, intake fairing and nozzle housing.

9. A safety arrangement for an aircraft jet propulsion engine substantially as hereinbefore described with reference to the accompanying drawings.