Portable non-gravitational positive pressure generator and method of use

An apparatus for applying non-gravitational pressure to a surface includes a frame structure having a longitudinal axis, a pair of connecting members coupled to the frame structure along parallel axes normal to the longitudinal axis of the frame structure, vacuum fasteners coupled to the connecting members to secure the frame structure on an underlying surface, a vacuum pump mounted on the frame structure for activating the vacuum fasteners and a positive pressure pump mounted on the frame structure for inflating a collapsible diaphragm to apply pressure to the underlying surface. The apparatus is useful for applying doublers to aircraft repair localized damage.

TECHNICAL FIELD 
The invention relates to a portable non-gravitational positive pressure 
generator for use in repairing thin skinned composite or similar 
structures such as an aircraft fuselage. 
BACKGROUND 
Many modern aircraft are constructed with composite components and 
laminates such as bonded honeycomb structures with relatively thin skin 
surfaces. These thin surfaces are susceptible to being easily dented or 
ruptured by, for example, the impact of a bird during flight. These thin 
skin surfaces are also susceptible to cracking due to mechanical stresses, 
environmental conditions or imperfections in the materials. Once a thin 
skinned aircraft component has been dented, cracked or ruptured, it is 
necessary to repair the surface in order to prevent further damage to the 
component. 
Advances in materials, particularly in adhesives, have permitted the repair 
of localized damage to thin skinned aircraft components with composite 
patches also known as doublers. Typically the area to be repaired is 
cleaned and a doubler or patch is adhesively bonded over the damaged area. 
However, the effectiveness of the adhesive and the integrity of the repair 
is often dependent upon the application of uniform pressure over the 
doubler for the period required to cure the adhesive. Additionally the 
geometry of the skin surface to be repaired may be planer, curvilinear or 
a combination of both requiring that the pressure be applied over a 
non-uniform, variable geometry. 
In the past, repair of thin skinned aircraft components such as a wing or 
fuselage section with doublers required, in many cases, that the component 
be removed from the aircraft, necessitating moving the aircraft to a 
hangar. For example, in the case of an aircraft wing, it was necessary to 
demate the wing from the aircraft and place the wing in a specially 
constructed large steel frame. Internal support structures connected to 
the steel frame restrained the wing during the application of positive 
pressure over the surface to which the doubler was applied. Due to the 
different sizes and geometries of the various aircraft components, 
different frames were required for different components and for the same 
components of different aircraft. In some cases the necessary equipment to 
apply a doubler was not available at the site where the damaged aircraft 
was located. Additionally, the operation was extremely labor intensive, 
expensive and required extensive downtime for the aircraft. 
SUMMARY OF THE INVENTION 
The present invention provides a portable non-gravitational positive 
pressure generator for use in repairing thin skinned composite or similar 
structures such as an aircraft fuselage. The invention significantly 
reduces the amount of time, labor and equipment required to effect 
repairs, thereby reducing expense and aircraft downtime.

DETAILED DESCRIPTION 
Referring now to FIG. 1, the portable non-gravitational positive pressure 
generator 10 of the present invention includes a central frame member or 
frame structure 12 and connecting members 14. A pair of legs 13 are 
mounted on opposing ends 15 of the central frame member for supporting the 
portable non-gravitational positive pressure generator 10. The connecting 
members 14 may be slidably mounted on the central frame member 12 for 
adjustment in a longitudinal direction relative to the frame member 12 
parallel to axis A--A'. The longitudinal axis of connecting members 14 
intersect the longitudinal axis of central frame member 12 at an angle of 
approximately 90.degree.. Central frame member 12 and connecting members 
14 may be manufactured from any suitable material such as steel, aluminum 
or a sufficiently strong, rigid polymeric material. As illustrated, 
central frame member 12 and connecting members 14 are rectangular in 
crosssection, but it is anticipated that central frame member 12 and 
connecting members 14 could be tubular, hexagonal, octagonal or some other 
geometry. 
A plurality of vacuum fastener assemblies 16 are mounted on the connecting 
members 14 in a generally rectangular configuration. In the embodiment 
illustrated in FIG. 1, two pair of vacuum fastener assemblies are coupled 
to a pair of connecting members 14 and positioned along parallel axes 
normal to the longitudinal axis of central frame member 12. The vacuum 
fastener assemblies 16 may be slidably mounted for adjustment in the 
lateral direction relative to central frame member 12 and parallel to axis 
B--B'. As illustrated, the vacuum fastener assemblies 16 each comprise a 
vacuum type suction cup 17, a mounting plate 18 and a collar 20. Vacuum 
suction cups 17 may be made from any suitable flexible material such as a 
synthetic rubber or an elastomeric polymer. 
Also mounted on central frame member 12 are a series of ribs or spacers 22 
that are connected to plate 24. Plate 24 provides a uniform surface 
against which a collapsible bladder or diaphragm 26 reacts upon inflation. 
Ribs 22 are sized to position plate 24 at the appropriate location 
relative to central member 12 and vacuum fastening assemblies 16 to enable 
collapsible diaphragm 26 to be inflated against an underlying surface to 
which the vacuum suction cups 17 have been applied. 
A positive pressure pump 28 is mounted on central frame member 12 and is 
connected to collapsible diaphragm 26 via air line 30. Preferably, 
collapsible diaphragm 26 is constructed from an elastomeric rubbery 
material. It is however, anticipated that collapsible diaphragm 26 may be 
made from numerous materials known to those skilled in the art. 
A vacuum pump 32 is also mounted on central frame member 12 adjacent to 
positive pressure pump 28. Vacuum pump 32 is connected to vacuum type 
suction cups 17 through vacuum lines 34. If desired, positive pressure 
pump 28 and vacuum pump 32 may be equipped with pressure switches, 29 and 
35, respectively, for activating the positive pressure pump 28 and vacuum 
pump 32 to maintain predetermined levels of pressure and vacuum 
alleviating the need for manual switching or continuous operation of the 
pumps. 
Referring now to FIG. 2, there is illustrated a flow chart for repairs 
using the portable non-gravitational positive pressure generator 10 of the 
present invention. 
1. The surface area where the doubler or patch is to be applied is cleaned 
as necessary in step 50 and, if desired, an adhesive is applied during 
step 52 to the repair area and/or to the doubler or patch that will be 
used to effect the repair. 
2. The doubler or patch is applied over the damaged area in step 54. 
3. The portable non-gravitational positive pressure generator 10 is 
positioned in step 56 over the doubler or patch and the positions of the 
vacuum suction assemblies are adjusted if necessary during step 58. 
4. The vacuum pump 32 is turned on and vacuum is applied to the vacuum 
suction cups 17 through vacuum lines 34 in step 60 until the portable 
non-gravitational positive pressure generator 10 is secured in the desired 
position. 
5. The collapsible diaphragm or bladder 26 is positioned during step 62 
between plate 24 and the doubler and connected to the positive pressure 
pump 28 and inflated in step 64 to the desired pressure to apply the 
desired amount of uniform positive pressure against the doubler. 
6. The portable non-gravitational positive pressure generator 10 is 
maintained in position against the inflated collapsible diaphragm 26 
during step 66 by the action of the vacuum suction cups for the desired 
period to allow the adhesive to cure, bonding the doubler to the surface 
to be repaired. 
7. After the adhesive has cured, the collapsible diaphragm 26 is deflated 
in step 68 and removed in step 70. 
8. If necessary, the vacuum applied to the vacuum suction cups 17 is 
relieved and the portable non-gravitational positive pressure generator 10 
is removed. 
The foregoing method of repair alleviates the necessity for demating 
aircraft components such as wings from an aircraft in order to effect 
repairs to localized areas. The foregoing method also alleviates the 
necessity for large complicated repair frames in which to support such 
components during repair. The expense, labor and aircraft downtime 
previously required to accomplish such repairs is also reduced. 
Although the invention has been illustrated in the accompanying Drawings 
and described in the foregoing Detailed Description, it will be 
appreciated by those skilled in the art that various modifications and 
rearrangements of the component parts and elements of the present 
invention are possible without departing from the spirit and scope of the 
invention. The following claims are intended to cover all such 
modifications within the scope of the invention.