Folding, plug type aircraft door

A plug type door for a pressurizable aircraft fuselage is mounted by a door hinge assembly for swinging movement into and out of a door opening in the fuselage. The door is composed of three segments that are hinged to each other so that the door can be folded from a fully closed position in which the three segments are serially arranged to completely cover the door opening, into an unplugged position in which the three segments are oriented in a generally Z-shaped configuration. Stop members are mounted on the fuselage adjacent the door opening and cooperate with corresponding stop members on the door to plug or secure the door in the door opening when the door is in a closed position. The stop members on the door and the door opening deregister as the door is folded to free the door for outward swinging movement about the hinge assembly.

BACKGROUND OF THE INVENTION 
The present invention relates to door assemblies for closing a door opening 
in a wall and more particularly to a plug type aircraft door that is 
constructed to withstand internal cabin pressure when in a closed position 
and yet that can be opened outwardly from the fuselage through the door 
opening. 
Aircraft having pressurizable passenger cabins normally employ ingress and 
egress doors that are generally referred to as plug type doors. Plug type 
doors are seated in the fuselage door opening and secured in that opening 
so that when the passenger cabin is pressurized, the internal pressure on 
the door will not cause the door to blow out. Such plug type doors are 
normally larger in at least one dimension, either horizontally or 
vertically, than the door opening. Thus such doors either must be opened 
inwardly, utilizing valuable passenger deck space, or must be constructed 
so that they can be moved outwardly through a door opening that is smaller 
than the door itself. 
Since cabin space is at a premium, most commercial aircraft in use today 
utilize plug type doors that are modified in configuration during the 
opening sequence to reduce the size of the door relative to the opening or 
are reoriented relative to the door opening during the opening sequence so 
that the doors can be moved outwardly through the door opening. One such 
door is disclosed in U.S. Pat. No. 3,051,280 to Bergman, Eisenhart and 
Wood. The door disclosed in the Bergman et al. patent has retractable tabs 
mounted at the upper and lower edges of the door that seal the gap between 
the upper and lower edges of the door and the lintel and sill, 
respectively, of the door opening when the door is closed. The retractable 
tabs are moved inwardly by an actuator during the opening sequence to 
decrease the vertical dimension of the door. The Bergman et al. hinge 
mechanism then allows the door to be moved inwardly, rotated through 
approximately 90.degree. and then swung outwardly through the door 
opening. Since, however, the door must rotate inwardly, valuable cabin 
space must always remain free of obstacles so that the door can be opened 
at any time. 
It is accordingly a broad object of the present invention to provide a plug 
type door for an opening in a wall, and specifically for a door opening in 
an aircraft fuselage, that is configured so the door can be swung through 
the door opening without substantial inward movement relative to the door 
opening; that is relatively simple in design when compared with prior art 
plug type doors; and that reduces or virtually eliminates the seal 
abrasion problems of the prior art. 
SUMMARY OF THE INVENTION 
In accordance with the foregoing objects, and other objects that will 
become aparent to one of ordinary skill upon reading the following 
specification, the present invention is embodied in a plug type door 
assembly for covering an opening in a wall, for example, a doorway in the 
fuselage of an aircraft. The plug type door of the present invention 
comprises a segmented door panel having first and second end segments and 
an intermediate segment. When the door is closed, the segments are 
serially arranged in a generally continuous path so that the peripheral 
edge portions of the door segments lie adjacent the periphery of the 
doorway so as to close the doorway. Disengageable stop means are 
operatively associated with the doorway and the door for securing the door 
in the doorway against fluid pressure exerted upon one side of the closed 
door. A seal means is operatively associated with the door to seal the 
peripheral edge portions of the door segments to the periphery of the 
doorway when the door is in a closed position. Hinge means join the end 
segments of the door to the intermediate segment so that the door can be 
folded at the junctions of the end segments and the intermediate segment 
into a generally Z-shaped configuration. As the door is folded into the 
Z-shaped configuration, and the end segments of the door move toward each 
other, the movement of the end segments disengages the stop means, thus 
freeing the door from the doorway. 
In a preferred form of the invention, the door and doorway have generally 
hexagonal shapes. The intermediate segment spans the central portion of 
the door between two opposite apexes of the hexagon. As the door is folded 
into its Z-shaped configuration, not only are the opposite ends of the 
door moved away from the corresponding portion of the periphery of the 
doorway as the end segments move toward each other, but also the side 
portions of the end segments are translated away from the corresponding 
side portions of the doorway. Thus, as the door is folded into its 
Z-shaped configuration, the seal means associated with the peripheral edge 
portions of the door are spaced from the doorway periphery. The only 
dimension of the door that remains substantially the same as the 
corresponding dimension of the doorway is the span of the intermediate 
segment across the central portion of the doorway. The seal means 
associated with the peripheral edge portions of the intermediate segment 
of the door are retracted during the folding operation so as to disengage 
that portion of the seal from the door opening, thus completely freeing 
the door from the doorway and minimizing abrasion and wear on any portion 
of the seal.

DETAILED DESCRIPTION OF THE INVENTION 
Referring first to FIGS. 1, 2 and 3, the door 10 of the present invention 
functions to close an opening 12 in a wall structure 14. In the preferred 
form of the invention, the door 10 is a plug type door for closing a 
passenger ingress and egress doorway from the pressurized passenger cabin 
of an aircraft to outside the fuselage. The invention will be described in 
terms of its utilization as a plug type door for an aircraft, however, it 
is to be realized that the door can be employed for closing doorways or 
other openings in all structures, but especially those that require a 
pressure seal and means for securing the door in the door opening against 
internal or external fluid pressure on the door. Thus, for purposes of the 
ensuing description, the door opening will be referred to as a fuselage 
doorway, while the wall structure in which the doorway is situated will be 
referred to as an aircraft fuselage. 
The preferred peripheral configuration of the doorway 12 is a generally 
hexagonal shape with the junctions or apexes of the sides of the hexagon 
smoothly rounded. Moreover, the doorway is preferably elongated in the 
vertical dimension and foreshortened in the transverse dimension to 
conform the height and width dimensions of the doorway to generally 
acceptable dimensions for normal passenger ingress and egress. For ease of 
manufacture and interchangeability of the doors with doorways on both 
sides of the fuselage, it is also preferred that the doorway be 
symmetrical about a generally vertical axis. In the preferred form of the 
invention, the bottom portion or sill 12a of the doorway is situated 
adjacent the passenger deck 16 of the aircraft while the upper portion or 
lintel 12b is spaced upwardly from the bottom portion 12a by a distance 
sufficient to allow ingress and egress for passengers of normal height. 
The central portion 12c of the doorway has a transverse dimension that is 
wider than the transverse dimension of the remainder of the doorway. The 
periphery of the doorway extends upwardly from the central portion 12c 
with converging sides merging into the upper portion 12b of the periphery 
of the doorway. Likewise, the sides of the doorway below the central 
portion 12c converge downwardly and merge into the bottom portion 12a of 
the doorway periphery. 
The door 10 in its presently preferred form comprises three segments: an 
upper segment 18, an intermediate segment 20 and a lower segment 22. The 
upper and lower segments 18 and 22 when viewed from the inside of the 
fuselage can be mirror images of each other, or can be dissimilar. It is 
most preferred, however, that the door be symmetrical about a vertical 
axis so that the door is interchangeable with doorways on both sides of 
the fuselage. The intermediate segment 20 extends generally horizontally 
to span the central portion 12c of the doorway and has edge portions 20a 
and 20b that conform to the curvature of the central portion 12c of the 
periphery where the convergent upper and lower portions of the doorway 
periphery sides meet in a smooth, rounded curve. The vertical dimension of 
the intermediate segment 20 is relatively small compared to the 
corresponding vertical dimensions of the upper and lower segments 18 and 
22. The upper segment 18 of the door has peripheral edge portions that 
generally conform to and lie adjacent the upper side portions and the 
upper portion of the periphery of the doorway. Likewise, the lower segment 
22 has peripheral edge portions that converge downwardly from the 
intermediate segment 20 and conform generally to the shape of the lower 
side portions and the bottom portion of the doorway periphery. The upper 
horizontal edge of the intermediate segment 20 is joined to the lower 
horizontal edge of the upper segment 18 by a hinge 24. Likewise, the lower 
edge of the intermediate segment 20 is joined to the upper edge of the 
lower segment 22 by a similar hinge 26. Both hinges 24 and 26 are 
illustrated as piano hinges; however, it is understood that any suitable 
hinge structure can be utilized as an alternate for a piano hinge 
structure. The upper hinge 24 joining the intermediate segment 20 and the 
upper segment 18 of the door is constructed so as to allow the upper 
segment of the door to rotate about the hinge axis in a counterclockwise 
direction relative to the intermediate segment. The lower hinge 26 joining 
the intermediate segment 20 and the lower segment 22 of the door is also 
constructed to allow the lower segment 22 of the door to rotate in a 
counterclockwise direction relative to the intermediate segment 20. As 
will be explained in greater detail below, the hinge structure thus allows 
the door to be foreshortened in the vertical dimension. When the door is 
fully closed, latched and secured in the door opening, as illustrated in 
FIGS. 1, 2 and 3, the outer skins 18c, 20c and 22c, respectively, of the 
upper, intermediate and lower segments 18, 20 and 22 are serially aligned 
to form a generally continuous exterior surface that conforms to the 
exterior surface configuration of the fuselage 14, thus providing a 
continuous, aerodynamic fuselage and door structure when the door is 
closed. 
A continuous peripheral fluid pressure seal 30 is affixed to the peripheral 
edge portions of the door adjacent the outer skins 18c, 20c and 22c. The 
pressure seal is of a conventional type normally utilized with aircraft 
doors and can be one of several seal configurations available in the art. 
A preferred seal configuration will be described in greater detail below. 
When the door is closed, the pressure seal 30 engages the periphery of the 
doorway 12 and a shoulder 14b (shown best in FIGS. 13 and 14) formed by a 
projection of the outer skin 14a of the fuselage 14 into the doorway to 
prevent fluid leakage between the door/doorway interface. Still referring 
to FIGS. 1 through 3, in the preferred embodiment of the invention, the 
fluid seal 30 is employed to prevent pressurized cabin air from escaping 
the passenger cabin when the air pressure exterior of the fuselage is less 
than that in the pressurized cabin. It is preferred that the seal engage 
the door frame 12d with sufficient force to also prevent ingress of fluid 
from outside the door. 
Stops of two different types are employed in the preferred embodiment of 
the door to plug or secure the door in the opening and prevent the door 
from blowing out when the cabin pressure exceeds the external pressure of 
the fuselage. A plurality of interengageable arm type door stops 32 
(hereinafter "arm stops") are employed in conjunction with a plurality of 
cam type door stops or guides 34 and 36 (hereinafter "cam stops" 34 and 
36). The arm stops 32 are associated with both the upper and lower 
segments 18 and 22 of the door 10. Four arm stops 32 are employed along 
each of the sides of the upper segment 18 while a similar set of four arm 
stops 32 are employed along each of the sides of the lower segment 22. 
Only two of the arm stops can be seen adjacent the lower right hand 
portion of the door because hinge structure (to be described in greater 
detail below) excludes the remaining two stops from view. 
Referring to the upper left hand one of the arm stops 32 as shown in FIG. 
1, each of the stops comprises a door arm 32a and a doorway arm 32b. The 
doorway arm 32b is mounted on the door frame 12d and extends transversely 
into the doorway a relatively short distance at a location inside the 
closed position of the door 10. The door arm 32a is affixed to the door 
adjacent the end of the doorway arm 32b, is spaced from the door frame 12d 
and extends behind and overlaps the doorway arm 32b. The overlapping 
portions of the door arm 32a and doorway arm 32b have mutually 
interengageable stop surfaces that are in sliding contact when the door is 
in a closed position. Thus an outward fluid pressure force on the door 10 
will be transmitted through the door arm 32a to the doorway arm 32b and 
thus to the door frame 12d. The remaining ones of the arm stops 32 are 
constructed in a similar manner and are spaced at predetermined locations 
about the periphery of the doorway so that a fluid pressure on the inside 
of the door will be transmitted evenly through a plurality of points to 
the surrounding fuselage structure to prevent the door from blowing out of 
the doorway when the door is closed. Although no arm stops are illustrated 
at the upper and lower ends of the door, it is to be understood that arm 
stops similar to stops 32 can be employed along the upper and lower edges 
of the door and door frame. 
The upper and lower cam stops 34 and 36 serve three functions: first as a 
stop when the door is in a closed position to react negative pressure 
loads from outside the door; secondly to act as a fail safe stop in the 
event of failure of an adjacent arm stop; and primarily to guide the upper 
and lower door segments 18 and 22 along a predetermined path when the door 
is unplugged from the opening. Two upper cam stops 34 are employed at each 
side of the upper segment 18 of the door while two vertically spaced lower 
cam stops 36 are employed along each side of the lower segment 22 of the 
door. Each of the cam stops includes a doorway cam bracket 34a and 36a 
mounted on the door frame 12d and extending transversely into the doorway 
a short distance. The upper and lower cam brackets 34a and 36a carry 
guideways 34b and 36b in which followers 34c and 36c reside when the door 
is in a closed and plugged position. The followers 34c and 36 c are 
rotatably mounted on follower brackets 34d and 36d, in turn affixed to the 
door frame adjacent the cam brackets 34a and 36a. The two upper guideways 
34b each extend from an upper terminus downwardly and slightly inwardly 
relative to the fuselage. An outwardly extending portion joins the lower 
end of the downwardly and inwardly extending portion and opens outwardly 
to provide an exit path for the followers 34c. The four lower cam stops 36 
have similar guideways 36c except that each of the guideways in the four 
lower stops 36 extends from a lower terminus generally upwardly and 
outwardly. An outwardly extending portion of the guideways joins the 
upwardly and outwardly extending portion of the guideways and opens 
outwardly relative to the fuselage to provide an exit path for the 
followers 36c. When the door 10 is in a closed position, the followers 34c 
in the two upper cam stops 34 reside at the upper terminus of the 
guideways 34b while the followers 36c engaging the guideways 36b in the 
four lower cam stops 36 reside in the lower termini of the guideways 36c. 
Thus the cam stops 34 and 36, in conjunction with the arm stops 32, 
securely fasten the door in the doorway and most will aid in preventing 
blowout of the door when the cabin pressure exceeds the pressure external 
to the fuselage, and will react any inwardly acting force on the door. 
A door actuating assembly, generally designated 40, is located inwardly 
from and adjacent the lower segment 22 of the door. A hinge assembly 42 
supports the door actuating assembly 40 and extends transversely to one 
side of the doorway where it is affixed to the door frame 12d. The door 
actuating assembly 40 is operably coupled to the upper and lower segments 
18 and 22 of the door and, when manually actuated, functions to pull 
downwardly on the upper segment 18 of the door and upwardly on the lower 
segment 22 of the door. As this occurs, the intermediate segment 20 
rotates about the hinges 24 and 26 so that the door is folded in 
longitudinal section into a Z-shaped configuration as shown in FIGS. 4, 5 
and 6. The actuating assembly 40 is so connected to the upper and lower 
segments 18 and 22 as to move the upper portion 18a of the upper segment 
18 downwardly and slightly inwardly relative to the doorway while the 
lower portion of the upper segment 18 is moved downwardly and inwardly as 
it rotates about the hinge 26. The upper portion 22a of the lower segment 
is moved upwardly relative to the doorway while the lower portion of the 
lower segment is moved upwardly and slightly inwardly relative to the 
doorway. As the upper and lower segments 18 and 22 are moved downwardly 
and upwardly, respectively, the intermediate segment 20 rotates about both 
hinges 24 and 26 from a closed position (as shown in FIG. 3) through an 
arc of about 110.degree. so that the upper portion of the intermediate 
segment 20 resides below the lower portion of the intermediate segment 20 
when the door is Z-folded (as shown in FIG. 6). 
Referring to FIGS. 4 through 6, as the door is folded into its Z-shaped 
configuration, it is disengaged from the arm stops 32 and from the cam 
stops 34 and 36. Since the upper and lower segments are moved downwardly 
and upwardly, respectively, the door arms 32a on the upper segment are 
deregistered in a downward direction from the doorway arms 32b. Likewise 
the door arms 32a on the lower segment 22 of the door are deregistered in 
an upward direction relative to the doorway arms 32b. Thus the engagement 
surfaces of the arm stops are offset from each other, allowing the door to 
be swung outwardly relative to the doorway about the hinge assembly 42. As 
the door is Z-folded from its fully closed position, the lower portion of 
the upper segment 18 and the upper portion of the lower segment 22 are 
guided through an arcuate path by virtue of the respective 
interconnections to the intermediate segment 20 by the hinges 24 and 26. 
The upper portion of the upper segment 18 is guided by the upper guideways 
34b of the two upper cam stops 34 downwardly and inwardly. Thus, as the 
followers 34c traverse the downwardly and inwardly oriented portion of the 
guideways 34b, the upper portion of the upper segment 18 is guided 
downwardly and inwardly so that at the completion of the Z-folding of the 
door, the followers 34c reside within the outwardly opening portion of the 
guideways 34b. Likewise, as the lower segment 22 of the door is pulled 
upwardly by the actuating mechanism 40, the followers 36c of the four 
lower cam stops ride upwardly in the guideways 36b of the four lower cam 
stops 36. At the completion of the Z-folding of the door, the followers 
36c of the lower cam stops all reside in the outwardly opening portions of 
the lower guideways 36b. In this manner, the door 10 is completely 
disengaged from the cam stops 34 and 36 and the arm stops 32; that is, the 
door is unplugged from the doorway 12 and is ready to be swung outwardly 
to open the doorway. 
The base member 48 of the actuating apparatus 40 is mounted adjacent the 
upper end of the lower segment 22 of the door. A shaft 50 is rotatably 
journalled in the base member 48. The shaft 50 is oriented generally 
horizontally and extends from a location adjacent the outer skin 22c of 
lower segment 22 inwardly to the inside of the door. The hub 52a of a 
manually-actuatable handle 52 is affixed to a stub shaft 54 projecting 
inwardly from the inner end of shaft 50. A cam member 56 is mounted on the 
shaft 50 at a location spaced outwardly from the hub 52a of the handle 52 
and carries a cam guideway 58 that extends in a generally arcuate path 
about the shaft 50 and opens outwardly relative to the door. The guideway 
58 has a lower portion that is situated adjacent the bottom of the shaft 
50 when the handle 52 is in its normally closed position and extends in an 
arcuate path in a clockwise direction around the hub (when viewed from the 
inside of the door 10). The cam guideway 58 follows an arc that is 
situated at an ever increasing radius relative to the shaft as it extends 
upwardly and around the shaft 50. The upper end of the guideway 58 
terminates above the shaft 52. 
An L-shaped follower arm 60 has its one end pivotally mounted on the base 
member 48 via a pivot pin 62. The pivot pin 62 is located on the opposite 
side of the shaft 50 from the guideway 58. One leg of the follower arm 60 
extends downwardly from the pivot pin 62 under the shaft 50 and joins with 
the other leg of the follower arm in a 90.degree. curve. The other leg of 
the follower arm 60 then extends upwardly and terminates at a location 
spaced radially outwardly relative to the shaft from the guideway 56. A 
follower 64 is pivotally mounted on the central curved portion of the 
follower arm 60 and engages the lower portion of the guideway 58 in the 
cam member 56 when the actuating handle 52 is in its closed and plugged 
position. 
The entire door 10 is suspended from a main hinge arm 68 that extends 
transversely across the door opening from the hinge assembly 42. The end 
68a of the hinge arm adjacent the doorway periphery is coupled to the 
hinge assembly 42 in a manner that will be described in greater detail 
below. The inner end 68b of the hinge arm 68 terminates centrally of the 
door opening in the transverse direction adjacent and below the base 
member 48 of the actuating apparatus 40. Two support arms 70 and 72 that 
are integral with the hinge arm 68 extend upwardly from the inner end 68b 
of the hinge arm. The support arms 70 and 72 are spaced transversely from 
opposite sides of the base member 48 and have upper ends terminating at a 
location slightly above the base member 48. An upper support shaft 74 
extends transversely between the upper ends of the support arms 70 and 72 
and has its ends respectively journalled in the upper ends of the arms 70 
and 72. The shaft 74 is located above the base member 48. A pair of 
downwardly and outwardly extending suspension arms 76 and 78 are affixed 
to the shaft 74. The lower ends of the suspension arms 76 and 78 are 
pivotally coupled, respectively, to the upper ends of a pair of upright 
coupling links 80 and 82. The lower ends of the links 80 and 82 are 
pivotally coupled to a pair of transversely spaced yokes 84 and 86, that 
are in turn fixed to and extend upwardly from the upper portion of the 
base member 48. Thus, the base member 48 is suspended from shaft 74 via 
suspension arms 76 and 78, coupling links 80 and 82 and yokes 84 and 86; 
and thus the entire lower segment 22 of the door is suspended from the 
main hinge arm 68. 
As previously mentioned, the L-shaped follower arm 60 extends upwardly from 
below the main actuating shaft 50. The outer end 60a of the follower arm 
60 terminates adjacent the left support arm 70 on the main hinge arm 68. 
The outer end 60a of the L-shaped cam arm also is located below the 
location of shaft 74 where it is journalled in the support arm 70. An 
inwardly and slightly upwardly extending actuating arm 88 is affixed to a 
stub shaft extension 74a of the shaft 74. The outer end of the actuating 
arm 88 terminates above the upper end of the follower arm 60 and is 
pivotally coupled to the upper end 60a of the follower arm 60 via 
actuating link 89. 
As shown in FIGS. 1, 2 and 3, the actuating handle 52 extends transversely 
toward the hinge assembly when the actuating assembly is in its closed and 
plugged position. To unplug the door 10 from the doorway 12, the handle 52 
is rotated in a counterclockwise direction as indicated by arrow 94. As 
the handle 52 is rotated through approximately 180.degree. to the position 
shown in FIGS. 4, 5 and 6, the cam member 56 is rotated via its connection 
to actuating shaft 50 (also rotated through about 180.degree.) so as to 
cause the arcuate guideway 58 to swing about the rotational axis of main 
shaft 50. As this occurs, the ever increasing radius of the guideway 58 
causes the follower 64 to move downwardly relative to the shaft 50. As the 
follower 64 moves downwardly, the outer end 60a of the L-shaped follower 
arm 60 will also move downwardly. The downward movement of the outer end 
60a of the follower arm pulls downwardly on the actuating link 89, which 
motion is transmitted via actuating arm 88 to the support shaft 74, 
causing the shaft 74 to rotate in a clockwise direction, as indicated by 
arrow 91 (FIG. 2). As the shaft rotates, the lower ends of the suspension 
arms 76 and 78 traverse an arcuate path in a clockwise direction with the 
shaft 74 pulling upwardly on coupling links 80 and 82 and thus pulling 
upwardly on the base member 48. As the base member 48 is pulled upwardly, 
the lower segment 22 of the door 10 is also pulled upwardly to deregister 
the arm stops 32 and to move the followers 36c upwardly in the guideways 
36b from the plugged position as shown in FIGS. 1 through 3 to the 
unplugged position as shown in FIGS. 4 through 6. 
Referring to FIGS. 1 through 3, to prevent the lower end of the door from 
swinging outwardly about the hinge 24 once the followers 36c reside in the 
outwardly opening portion of the guideways 36b a keeper linkage, generally 
designated 90, flexibly attaches the bottom portion of the lower door 
segment to the main hinge arm 68. Two keeper arms 93 and 95 extend 
downwardly from the inner end 68a of the main hinge arm 68 in opposite 
directions from the support arms 70 and 72. A transversely extending 
keeper shaft 96 having two parallel, upwardly extending arms 98 and 100 
affixed thereto is journalled in the lower ends of the keeper arms 93 and 
95. A double yoke bracket 102 is attached by suitable fasteners to the 
lower central portion of the lower segment 22. Each of the yokes 102a and 
102b on the bracket 102 is spaced by the same distance that arms 98 and 
100 are spaced on the keeper shaft 96. A pair of connecting links 104 and 
106 are pivotally connected by pins at their respective ends to the yokes 
102a and 102b and the upwardly extending arms 98 and 100. 
When the door 10 is in its closed and plugged position (FIGS. 1 through 3), 
the keeper linkage 90 can pivot about the various rotational axes thereof 
so as to allow the followers 36c in the lower cam stops 36 to rest in the 
bottom of the guideways 36b as shown in FIG. 3. When, however, the door is 
unplugged by rotation of the actuation handle 52, the keeper linkage 90 
allows the door to move upwardly and slightly outwardly as shown in FIG. 
6. A stop arm 99 illustrated best in FIG. 2 extends transversely to the 
keeper arm 95 in a direction parallel with the keeper shaft 96 and behind 
the right hand arm 100. The stop arm 99 prevents the arm 100 from rotating 
too far in a counterclockwise direction when the door is in an unplugged 
position. If it were not for this stop, the bottom portion of the lower 
segment 22 of the door could swing out to a full extension of the arms 98 
and 100 and connecting links 104 and 106. If this occurred, it would be 
very difficult to close the door with a single pull on the actuation 
handle as the lower followers 36c would not completely seat at the inner 
end of the forwardly opening portion of the guideways 36b. Thus a second 
pull would have to be exerted on the bottom portion of the door to 
properly seat the followers 36c so that, upon rotation of the actuation 
handle 52, the followers could traverse downwardly into and seat in the 
bottom of the upwardly oriented portion of the guideway 34b. 
The upper segment 18 of the door is pulled inwardly and downwardly upon 
rotation of the actuation handle by coupling linkage, generally designated 
108, associated with the upper shaft 74. Referring to FIGS. 1, 2 and 3, 
the upper segment coupling linkage includes two upwardly and slightly 
outwardly extending coupling arms 110 and 112, each having their lower 
ends affixed to the rotatable shaft 74 at spaced locations. The upper ends 
of the arms 110 or 112 are pivotally connected by suitable pins to 
connecting links 114 and 116. The upper ends of connecting links 114 and 
116 are privotally connected by suitable pins links 114 and 116 to a pair 
of downwardly extending yokes 118a and 118b forming part of a double yoke 
bracket 118. The double yoke bracket 118 is affixed to a structural panel 
120 that extends inwardly from the lower portion of the upper door segment 
18 immediately above the upper hinge 26. 
When the actuating handle 52 is in its closed position, the pivotal 
connections between the arms 110 and 112 and the connecting links 114 and 
116 lie outboard of a plane defined by shaft 74 and the axes of the 
pivotal connections between connecting links 114 and 116 and yokes 118a 
and 118b. When the pivotal connections between the arms 110 and 112 are so 
located, and when an internal cabin pressure exists that is greater than 
the external pressure on the aircraft, the links cannot be forced across 
the previously mentioned plane. Thus the overcenter location of the 
pivotal connections of arms 110 and 112 and links 114 and 116 prevents the 
door from being inadvertently opened when the cabin is pressurized. 
When the actuation handle 52 is rotated from its closed to its open 
position as shown in FIGS. 4, 5 and 6, the shaft 74 rotates in a clockwise 
direction, indicated by arrows 91, as previously described. As the shaft 
74 rotates, the upper ends of arms 110 and 112 are swung inwardly and 
downwardly relative to the axis of shaft 74, pulling downwardly on the 
links 114 and 116 and thus pulling the lower portion of the upper segment 
18 of the door downwardly and inwardly. As this occurs, the upper 
followers 34c associated with the upper cam stops 34 move from their 
seated locations in the upper portions of the downwardly and inwardly 
extending guideways 34b and are positioned adjacent the outwardly opening 
portion of the guideways 35b. 
Thus, in a single movement of the actuating handle 52 from its closed 
position as shown in FIGS. 1, 2 and 3 to its unlocked position as shown in 
FIGS. 4, 5 and 6, the door is moved from a closed and plugged position to 
an unplugged position ready for swinging movement outwardly through the 
doorway. It is to be understood that the door is moved back to its plugged 
position by simply rotating the handle 52 in a clockwise direction, 
reversing the motion of the actuating linkage and thereby plugging the 
door 10 in the doorway 12. 
To assure that the upper segment 18 of the door is secured so that it will 
not move upwardly during opening of the door, an upper segment locking 
mechanism is actuated upon rotation of the handle 52. Referring again to 
FIGS. 1 and 2, a radial arm 56a extends downwardly from the cam member 56 
when the actuating handle 52 is in its closed position. As the actuating 
handle is rotated approximately 180.degree. to its open position, the 
downwardly extending arm rotates through the same arc and is moved to an 
upright position as shown in FIGS. 4 and 5. The end of the arm 56a carries 
a slot that engages a pin 118a as the arm 56a rotates toward its upright 
position. The pin 118a extends inwardly from a mounting bracket 118b in 
turn connected to the central portion of the double yoke bracket 118. 
Thus, as the upper segment 18 of the door moves downwardly and inwardly, 
so does the pin 118a. The pin 118a and the mounting bracket 118b are so 
sized and positioned that the slot 56b in the radial arm 56a will engage 
the pin 118a when the actuation handle 52 is in its unlatched position. 
The door is thereby secured against being inadvertently moved upwardly 
while the door is in an open position. 
Additionally, a latch mechanism is provided to prevent the handle 52 from 
being rotated back to its plugged position when the door is open. A small 
tab 56c extends upwardly from the upper portion of the cam member when the 
actuating handle is in a closed position. As the actuating handle is 
rotated through 180.degree., the tab is moved to the bottom of the handle 
assembly. The latch mechanism 200, mounted on the main hinge arm 68 below 
the main shaft 50 and cam member 56, engages the backside of the tab 56c 
as the door is opened. The latch mechanism 200 includes a mounting bracket 
202 carrying a horizontally oriented shaft 204. An arm 206 is affixed to 
the latch shaft 204 and extends upwardly and inwardly when the door is in 
a closed position. A second arm 208 extends downwardly from the opposite 
end of the shaft and carries at the end opposite the shaft connection a 
pin that extends horizontally and parallel to the shaft 204 toward the 
main hinge link 132. An extension of the pivot pin 138 coupling the main 
hinge link 132 to the connecting link 134 extends downwardly behind the 
pin 210 and engages the pin 210 when the door is in a closed position. A 
biasing spring 212 is mounted between the main hinge arm 68 and the pin 
carrying arm 208 to exert a biasing force on the arm 208 which biases the 
latch shaft 204 in a counterclockwise direction. As the door is opened, 
the horizontal pin 210 moves outwardly with the main hinge arm 68 and is 
disengaged from the pivot pin 138, allowing the latch shaft 204 to rotate 
in a counterclockwise direction. As this occurs, the latch member 206 
engages the tab 56c, thus preventing the actuating handle 52 from being 
inadvertently rotated in a clockwise direction to move the door segments 
to the latched position while the door is open. 
For actuation of the door into its Z-fold unplugged configuration from 
outside the door, an exterior opening handle 122 is provided. The exterior 
opening handle is mounted on a hub 124 in turn affixed to a splined shaft 
(not shown) that is axially slidable in a mating splined recess in the 
main actuating shaft 50. The handle is biased toward its innermost closed 
position by a suitable spring mechanism (not shown). When the door is 
opened from the inside, the exterior handle 122 is pushed outwardly by a 
cam mechanism (not shown) to free it for movement with the interior handle 
52. When it is desired to actuate the door from the outside, unplugging it 
and readying it for opening, the handle 122 is grasped at one or both of 
its diametrically spaced ends 122a and 122b and pulled outwardly so that 
it is spaced from the outer surface of the door 10. An internal stop (not 
shown) prevents the splined shaft from being pulled all the way out of the 
main actuating shaft 50. The handle is shown in the extended position in 
FIG. 8. When the exterior handle 122 is rotated, the main actuating shaft 
50 is rotated in a manner identical to that which occurs when the interior 
actuating handle 52 is rotated, causing the actuating apparatus 40 to 
function in a manner identically to that occurring when the door is opened 
from the inside. 
Referring now to FIGS. 7 and 1 in conjunction with the isometric view of 
FIG. 2, the main hinge arm 68 on which the actuating assembly 40 is 
mounted extends transversely from the central location of the actuating 
assembly 40 toward the periphery of the doorway 12, terminating short of 
the periphery of the doorway 12. The main hinge arm 68 is coupled by 
several links, described in greater detail below, to a doorway hinge 
bracket 126. As can be seen in FIGS. 2 and 7, a plurality of links 128, 
128', 130 and 130', 132 and 134 interconnect the main hinge arm 68 to the 
hinge bracket 126. The links are all pivotally coupled at their ends for 
movement about upright or generally vertical pivot axes. For purposes of 
concision, further discussion of links 128' and 130' will be omitted as 
their operation and function in the hinge assembly 42 is identical to that 
of links 128 and 130. Still referring to FIGS. 1, 2 and 7, the main link 
132 is pivotally connected at its upper end by pin 136 to an upper flange 
138 on the hinge bracket 126. The main hinge link 132 extends inwardly 
relative to the fuselage from its pivotal connection to the hinge bracket 
and in a L-shaped curve extends parallel to and along the inward side of 
the main hinge arm 68, terminating at the central portion of the main 
hinge arm 68. The terminus of the main hinge link 132 is coupled to the 
main hinge arm 68 via the connecting link 134. The terminus of the main 
hinge link 132 is pivotally coupled by pin 139 to a first end of the 
coupling link 134. The coupling link 134 extends outwardly relative to the 
door and into a slot 140 located in the main hinge arm 68 outwardly from 
the connecting link 134. The connecting link 134 then turns in an L-shaped 
curve back toward the door periphery but terminates short of the end of 
the main hinge arm 68 adjacent the door periphery and is there pivotally 
coupled by pin 142 to the main hinge arm 68. Thus, the main hinge link 132 
and the connecting link 134 serve as the primary supports for the main 
hinge arm 68 and thus the entire door. 
Programming links 128 and 130 adjust the lateral movement of the door as it 
is swung outwardly about the pivot pin 136. The first programming link 138 
is L-shaped and is pivotally coupled at the short leg of the L by pivot 
pin 144 to a second bracket 146 located at the upper end of the hinge 
bracket 126. The end of the long leg of the first programming link 128 
extends inwardly to the L-shaped curve and then toward the central portion 
of the door. The first programming link 138 terminates at its other end 
short of the location of the pivot pin 139 connecting the main hinge link 
132 to the connecting link 134. The second programming link 130 is 
pivotally connected at one end by pin 148 to the end of the long leg of 
the first programming link 128, extends across and above the main hinge 
link 132 where the central portion of the second programming link 130, is 
pivotally coupled to the main hinge link by a pin 150 and terminates at a 
second end above the end of the main hinge arm 68 adjacent the door 
periphery. At that location, the other end of the second programming link 
130 is pivotally connected by pin 152 to the main hinge arm 68. 
Referring now to FIGS. 8 and 9, as the door is swung open after it is 
unplugged, the main hinge link 132 swings outwardly toward the exterior of 
the fuselage. As the main connecting link 134 swings outwardly, the first 
programming link 128 causes the second programming link 130 to rotate in a 
counterclockwise direction. As it rotates, the main hinge arm 68 is pushed 
outwardly (transversely relative to the door as it opens) by the second 
programming link 130. The connecting link 134 follows the motion of the 
main hinge arm 68 and a space between the main connecting link 134 and the 
main hinge arm 68. As the door continues to swing outwardly from the 
doorway, the second programming link 130 continues to rotate in a 
counterclockwise direction until it is aligned in plan view with the main 
hinge arm 68. Thus the main hinge arm 68 and the entire door 10 are moved 
outwardly by a distance slightly less than twice the distance between the 
pivot pin 150 connecting the second programming link to the main hinge 
link and the pivot pin 152 connecting the second programming link to the 
end of the main hinge arm 68. When the door is fully open as shown in 
ghost outline in FIG. 8 and as shown in FIG. 9, the short leg of the main 
hinge link 132 extends outwardly and slightly away from the periphery of 
the doorway while the long leg of the main hinge link 132 thereafter 
extends outwardly and back in the direction of the periphery of the 
doorway. Thus, by the coaction of the positioning of the outer end of the 
long arm of the main hinge link 132 and the operation of the programming 
links 128 and 130, the door is positioned almost completely away from the 
door opening 12 to allow full use of the doorway without any substantial 
blockage by the open door. It is to be noted that the hinge linkage 
operates in a manner in conjunction with the Z-folded door to not require 
any interior cabin space as the door is opened, as is the case with prior 
art doors. Moreover, the hinge assembly 42 is relatively simple to 
manufacture, easy to service and requires little maintenance. 
As previously mentioned, a pressure seal 30 is affixed to the interior 
peripheral edge portion of the door, as shown in FIGS. 1 and 12. As best 
seen in FIGS. 12 and 13, the seal is of the resilient hollow tubular type 
having a substantially tangential flange 30a formed integrally therewith. 
The seal is preferably formed of a synthetic elastomeric material. The 
flange 30a is abutted against the interior surface of the outer skins 18c, 
20c and 22c of the door panel adjacent the peripheral edge portions of the 
door segments. The tubular portion of the seal 30 extends outwardly beyond 
the peripheral edge portions of the door segments; and when the door is in 
the closed position, the seal resiliently abuts the periphery of the 
doorway 12 adjacent the outer skin 14a of the fuselage 14, thus sealing 
the entire peripheral edge portion of the door to the periphery of the 
door frame 12d. A small shoulder 14b formed by a small extension of the 
outer skin 14a of the fuselage past the door frame 12d (or otherwise 
suitably formed by an interior shoulder in the doorway) prevents the seal 
from being squeezed outwardly through the gap between the peripheral edge 
of the door and the fuselage skin when internal cabin pressure is exerted 
on the seal. 
When the door is vertically foreshortened by manipulating the actuating 
mechanism 40 and thereby moving the upper segment 18 of the door 
downwardly and the lower segment 22 of the door upwardly, the seal 30 
around the peripheral edge portions of the upper and lower segments moves 
along with the door segments, thus spacing the seal 30 from the upper 
portion 12b of the doorway periphery and the lower portion 12a of the 
doorway periphery. At the same time, because of the unique hexagonal shape 
of the doorway and the corresponding hexagonal shape of the door, the seal 
along the sides of the upper segment moves downwardly by a distance that 
is also sufficient to clear the shoulder 14b surrounding the periphery of 
the doorway 12. Likewise the sides of the lower segment 22 move upwardly a 
distance sufficient to laterally space the seal around the sides of the 
lower semgent from the lower shoulder 14b around the lower portion of the 
periphery of the doorway 12 as fully illustrated in FIG. 4. 
The only portion of the seal that is not completely separated from the 
shoulder 14b by the folding movement of the door segments is the central 
portion of the seal 30, generally indicated by numerals 30a and 30b, that 
reside on the ends of the intermediate segment 20 of the door. The central 
portions 30a and 30b of the seal are retracted away from the shoulder 14b 
as the door segments are folded by a relatively simple pull cord 
arrangement illustrated in FIG. 1 and in FIGS. 10, 11, 13 and 14. 
Referring to FIGS. 1, 10 and 13, the central portion 30a and 30b of the 
seal carry integral pull tabs 164 and 166. The pull tabs 164 and 166 are 
connected respectively by pull cords 168 and 170 to respective ones of the 
connecting links 114 and 116 for connecting the coupling arms 110 and 112 
on folding shaft 74 to the upper segment 18 of the door. As previously 
described, as the shaft 74 is rotated in a counterclockwise direction, the 
arms 110 and 112 are swung forwardly relative to the door. This movement 
in turn swings the connecting links 114 and 116 forwardly as shown in FIG. 
11. Since the inner end of the pull cords 168 and 170 are connected 
respectively to the coupling links 114 and 116, the forward movement of 
the links 116 and 114 will exert an inward pulling force on the cords, and 
thus on the tabs 164 and 166 coupled to the central portions 30a and 30b 
of the seal 30 as shown in FIG. 14. The inward movement of the pull cords 
will pull the seal 30 away from the doorway periphery sufficiently far to 
clear the shoulder 14b on the fuselage. Thus the seal 30 completely clears 
the entire periphery of the door and the shoulder 14b as the door segments 
are folded to allow unrestricted movement of the door outwardly through 
the door opening. 
The present invention has been described in relation to a preferred 
embodiment. One of ordinary skill, after reading the foregoing 
specification, will be able to make various alterations, substitutions of 
equivalents and other changes without departing from the broad concept 
embodied in the door assembly disclosed. For example, a variety of 
actuating mechanisms for Z-folding the door can be substituted for the 
actuating mechanism 40. Moreover, the intermediate panel can, if desired, 
be divided into two generally horizontal segments with the two segments 
joined at their center by a third hinge. The intermediate segments could 
then fold into a W configuration as the upper and lower segments of the 
door move toward each other, thus accomplishing the same end result as the 
preferred embodiment illustrated and described. Other flexible members can 
also be employed to allow vertical foreshortening of the door. 
As will be appreciated, the invention has been disclosed in the form of a 
preferred embodiment in which both the door opening and the door are 
generally shaped in the form of a hexagon. The invention is applicable, 
however, to any door assembly for closing an opening in a wall, provided 
that the sides of the opening and the door are convergent in a direction 
away from a line bisecting the door and the opening into two not 
necessarily equal parts. Thus, the broad concept of foreshortening a door 
in a directon transverse to the bisecting line can be employed with a door 
having an elliptical or polygonal shape. For a door having a periphery 
generally configured in the shape of a polygon with at least four sides, 
the sides of the polygon on either side of a line joining two nonadjacent 
apexes of the polygon are convergent. A door panel for such a polygonal 
opening has at least first and second end segments and a junction means 
for joining the first and second segments. The door panel for the 
polygonal opening has a peripheral edge portion that conforms to the shape 
of the polygon when the door is covering the opening. The first and second 
end segments of the door panel have adjacent edge portions that lie 
generally parallel to the line joining two nonadjacent apexes of the 
polygon. The junction means must so join the first and second end segments 
as to align them to completely close the opening when the door is covering 
the opening. An actuating means can also be associated with the first and 
second end segments and the junction means for moving the adjacent edge 
portions of the first and second end segments in generally opposing 
directions transverse to the line joining the nonadjacent apexes and 
thereby spacing the peripheral edge portions of the door panel from the 
periphery of the opening. 
It is therefore intended that the grant of Letters Patent hereon be limited 
only by the definition contained in the appended claims.