Abstract:
A system for inspecting a surface of a beam covered by at least one structure. The system includes at least one nut clip attached to the beam used to couple the structure to the beam, and at least one spacer inserted between the beam and the structure for creating a gap between the structure and the beam. A micro fiber-optic borescope is used to view the surface of the beam covered by the structure without removing the structure. The surface is viewed by inserting a micro fiber-optic thread of the borescope into the gap. The system eliminates the need for costly and time consuming disassembly and removal of components mounted on the structure before an inspection of the condition of the beam can be made.

Description:
FIELD OF INVENTION 
     The invention relates generally to the use of micro fiber-optic technology to inspect a beam surface. More specifically, the invention relates to inspecting a concealed surface of a beam by inserting a micro fiber-optic thread of a micro fiber-optic borescope between the beam and a structure concealing the surface. 
     BACKGROUND OF THE INVENTION 
     Inspection of a beam, such as a floor beam of an aircraft, for corrosion and/or cracks, usually requires the removal of whatever structure is mounted on the beam, for example floor panels. If a complex structure, such as an aircraft lavatory, is mounted to the beam, removal of such a structure in order to inspect the concealed surface of the beam is difficult, labor intensive, and very costly. 
     For example, maintenance programs for a commercial airline aircraft typically require heavy maintenance checks to be performed between every 5 to 7 years. During heavy maintenance checks, the floor structure is inspected for corrosion damage by completely removing everything that is mounted to the floor beams, including floor panels and all structures above the floor panels. Corrosion damage to the aluminum floor beams of an aircraft most frequently happens around ‘wet’ areas, near entry doors and under lavatories and galleys, which can leak fluids. Such corrosion damage is most frequently found on the upper surface of the aluminum floor beam, and particularly around the fastener holes used to attach the floor panels to the floor beams. 
     In order to inspect the upper surface of the floor beam, the airline inspection crew must remove the lavatories, seats, galleys, closets, etc., and then remove the floor panels. On the average, removing one galley, taking up the floor panels, inspecting the beams, replacing beams or treating the beams with a corrosion inhibiting compound, and then replacing the floor and galley, can require over 600 hours of labor per galley (or lavatory, etc.), thereby making such an inspection/repair process very costly. 
     Therefore, it would be highly desirable to be able to inspect a concealed surface of a beam, such as an aircraft floor beam, without having to remove the structure mounted to the beam. 
     BRIEF SUMMARY OF THE INVENTION 
     In one preferred embodiment, the present invention is directed to a system for inspecting a surface of a beam covered by at least one structure. The system includes at least one nut clip attached to the beam used to couple the structure to the beam and create a gap between the structure and the beam. Additionally, the system includes a micro fiber-optic borescope used to view the surface of the beam covered by the structure without removing the structure. Alternatively, the system also includes at least one spacer inserted between the beam and the structure for creating the gap between the structure and the beam. The surface is viewed by inserting a micro fiber-optic thread of the borescope into the gap. 
     The present invention also involves a method for inspecting a surface of a beam covered by at least one structure. The method includes attaching the structure to the beam utilizing a nut clip having an upper leg and a lower leg, wherein the upper leg is shorter than the lower leg. The method also includes creating a gap between the beam and the structure utilizing the upper leg of the nut clip, and viewing the beam surface covered by the structure utilizing a micro fiber-optic borescope. Alternatively, the method includes inserting at least one spacer between the beam and the structure, thereby creating the gap between the beam and the structure. 
     In another preferred embodiment an apparatus is provided for securing panels over an upper surface of a support beam to permit inspection of the beam upper surface. The apparatus includes a plurality of nut clips attached to the beam for mounting the panels to the beam, and at least one spacer inserted between the beam upper surface and the panel. The spacer creates a gap between the beam upper surface and the panel. The gap is sufficient to introduce a micro fiber-optic thread of a micro fiber-optic borescope used to view the covered surface of the beam. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description and accompanying drawings, wherein; 
     FIG. 1 is a perspective view of a system for inspecting a surface of a floor beam covered by a floor panel, in accordance with a preferred embodiment of the present invention; 
     FIG. 2 is a top view of a nut clip included in the system shown in FIG. 1; 
     FIG. 3 is cross-sectional side view of the nut clip taken in accordance with section line  3 — 3  shown in FIG. 2; and 
     FIG. 4 is perspective view of a spacer included in the system shown in FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Although the preferred embodiments are described below in terms of inspecting floor beams of an aircraft, the invention should not be so narrowly construed or limited as to apply only to aircraft. It is envisioned that the invention is applicable to the inspection of a concealed surface of any beam, whether the beam be in an aircraft, bus, ship, building or any other structure. 
     FIG. 1 is a perspective view of a system  10 , in accordance with a preferred embodiment of the present invention, for inspecting an upper surface  14  of a floor beam  18  covered by a floor panel  22 . The term “floor beam” is intended to include any beam or structural member used to support floor panel  22 , for example, in the context of aircraft, the term “floor beam” includes aircraft seat tracks. 
     Inspection system  10  includes at least one nut clip  26 , at least one spacer  30  and a micro fiber-optic borescope  34 . Nut clip  26  attaches to a floor beam flange  36  and is used to mount floor panel  22  to floor beam  18  utilizing a fastener  38  that couples with nut clip  26 . Additionally, nut clip  26  creates a gap  42  between floor panel  22  and beam upper surface  14 , Nut clip  26  is described in detail below in reference to FIGS. 2 and 3. Flange  36  includes the beam upper surface  14 , a lower surface  46  and a plurality of flange apertures  48  used in mounting floor panel  22  to beam  18 . 
     Each floor panel  22  is coupled to floor beam  18  by attaching a pair of nut clips  26  to floor beam flange  36  such that a panel aperture  50  in each of the two corners along one edge of floor panel  22  align with the nut clips  26  and one of beam apertures  48 . Then a fastener  38  is inserted through the panel apertures  50  at each corner of panel  22 , through the related flange aperture  48  and threaded into the related nut clip  26 . Fastener  38  may comprise any fastener suitable to mount floor panel  22  to beam  18  via nut clip  26 , such as a bolt, a screw, or a high lock. Preferably, at least one spacer  30  is installed between floor panel  22  and beam upper surface  14  and positioned between the nut clips  26  at each corner of panel  22 , thereby creating gap  42  in the area between nut clips  26 . Spacer  30  is described in detail below in reference to FIG.  4 . 
     Micro fiber-optic borescope  34  is a hand held device that includes a micro fiber-optic thread  54  and a borescope viewing device  58 . When an imaging end  60  of micro fiber-optic thread  54  is inserted into gap  42 , images of beam upper surface  14  are transmitted through micro fiber-optic thread  54  to viewing device  58  where an inspector views the transmitted images. Alternately, micro fiber-optic borescope  34  may include an auxiliary device cable  61  used to connect borescope  34  to peripheral remote devices (not shown) such as a viewing monitor or an image recording device. 
     Referring to FIGS. 2 and 3, FIG. 2 is a top view of nut clip  26  and FIG. 3 is a cross-sectional side view of nut clip  26  along line  3 — 3  in FIG.  2 . Nut clip  26  includes an upper leg  62 , a lower leg  66  that includes a hole  64  and a means  65  for coupling fastener  38  with nut clip  26 , and an intermediate section  68  that joins upper leg  62  and lower leg  66 . In a preferred embodiment, lower leg  66  includes a first section  70  and a second section  74  that includes the fastener coupling means  65 . In this embodiment the fastener coupling means  65  includes a nut housing  78  and a nut  82  enclosed in housing  78 . In an alternate embodiment, the fastener coupling means includes a nut attached to lower leg second section  74 . In another alternate embodiment, hole  64  is threaded and the fastener coupling means includes threaded hole  64 . 
     Nut clip  26  attaches to floor beam flange  36  by inserting flange  36  between nut clip upper leg  62  and lower leg  66  such that upper leg  62  is in frictional contact with beam upper surface  14 , lower leg  66  is in frictional contact with flange lower surface  46 , and nut clip hole  64  aligns with one of flange apertures  48 . Additionally, upper leg  62  has a shorter length than lower leg  66  such that when nut clip  26  is placed on floor beam flange  36  the aperture  48  that aligns with nut clip hole  64  is free from interference by upper leg  62 . Furthermore, nut clip upper leg  62  creates gap  42  in the area adjacent upper leg  62 . Thus, by creating gap  42  and keeping flange aperture  48  free from interference, upper leg  62  allows a person inspecting floor beam  18  to insert borescope micro fiber optic thread  54  into gap  42  and view beam upper surface  14  around beam aperture  48 , which is an area where corrosion and damage are more likely to occur. 
     FIG. 4 is a perspective view of spacer  30  (shown in FIG.  1 ), in accordance with a preferred embodiment of the present invention. The preferred embodiment includes at least one spacer  30 . However, when a floor panel  22  is relatively small in size, the use of spacer  30  may not be necessary. In the preferred embodiment, spacer  30  includes a first leg  86 , a second leg  90  and an intermediate section  94  that joins first leg  86  and second leg  90 . For each floor panel  22  coupled to floor beam  18 , at least one spacer  30  is attached to beam flange  36  between the nut clips  26  positioned at the two corners along one side of the floor panel  22 . Alternately, a plurality of spacers  30  are attached to flange  36  at predetermined intervals between nut clips  26 . Spacer  30  attaches to floor beam flange  36  by inserting flange  36  between spacer first leg  86  and second leg  90  such that first leg  86  is in frictional contact with beam upper surface  14  and second leg  90  is in frictional contact with flange lower surface  46 . Additionally, spacer first leg  86  creates gap  42  in the area adjacent first leg  86 , thereby allowing a person inspecting floor beam  18  to insert borescope micro fiber optic thread  54  into gap  42  and view beam upper surface  14 . Preferably first leg  86  is shorter in length than second leg  90 . However, it is envisioned that first leg  86  could alternately have a length, equal to or longer than spacer second leg  90 . 
     In an alternate embodiment spacer  30  comprises a shim that is removably inserted between floor panel  22  and beam upper surface  14  during inspection of floor beam  18 . Therefore, when floor beam  18  is to be inspected, spacer  30  is temporarily inserted between floor panel  22  and beam upper surface  14 , thereby creating gap  42 . After gap  42  is created an inspector can insert micro fiber-optic thread  54  into gap  42  and view upper surface  14  via viewing device  58 . Spacer  30  can be any shape suitable to be removably inserted between floor panel  22  and beam upper surface  14  to create gap  42 . For example, shim  30  can be rectangular, oval or round, and have a constant thickness or be wedge shaped. Additionally, it is envisioned that spacer  30  may include a handle to aid in its insertion and removal. 
     In operation, an inspector accesses the floor beams  18  from under the beams  18 , for example from the cargo area of an aircraft. The inspector then inserts the imaging end  60  of micro fiber-optic thread  54  into gap  42 . Images are transmitted from imaging end  60  through micro fiber-optic thread  54  to viewing device  58 . Viewing device then creates high resolution video images of the images received and displays the images on an eye piece viewer  94  (shown in FIG.  1 ). Thus, using viewing device  58 , the inspector views the condition of beam upper surface  14 . Alternately, the images can be viewed on a larger viewing screen by connecting micro fiber-optic borescope  34  to the larger viewing screen using auxiliary device cable  61 . Additionally, the images of beam upper surface  14  can be recorded by connecting micro fiber-optic borescope  34  to a recording device using auxiliary device cable  61 . 
     By viewing beam surface upper  14  using system  10 , an inspector can determine the amount and severity of corrosion or damage occurring to beam  18  without having to completely remove all floor panels  22  and all other structures mounted to floor beams  18  above floor panels  22 . Additionally, gap  42  allows corrosion inhibiting compounds to be applied to beam upper surface  14  from below floor beam  18  without removing all the structures mounted to floor beam  18 . 
     While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.