Aircraft Sheet Metal Repair - At Lee Aerospace, we have over 50,000 square feet of assembly floor space and a highly skilled aerostructures assembly workforce. We can assemble anything from small tabletop groups to large groups. The details of these assemblies are assembled using bench top tools such as Mounting Jigs (AJ) and Floor Mounting Jigs (FAJ). Our installation techniques include solid rivet installation, fasteners, tooled holes, hand drilled holes, coordinated pilot holes (ATA), close tolerance hi-lok holes, wet installed fasteners, and riveter automatic.
We are qualified to assemble sealed 'wet' structural fins to meet your fuel tank requirements. We also seal the pressurized parts of the fuselage required to pass aircraft pressure tests without leaks.
Aircraft Sheet Metal Repair
Quality control of assemblies uses the progressive buyback technique. Sub-assemblies are purchased before being put into larger assembly tools. Detail parts are sourced from production drawings that describe the pilot hole production plan. Our current installers include:
Sheet Metal Repair
Lee Aerospace manufactures aviation tail cone assembly for OEM production. Our airframe manufacturing processes incorporate best practice anti-corrosion and lightning protection applications where applicable. The tail cone sections meet stringent prescribed loads and flight characteristics, as well as contain components that play many roles for different airframes. An aviation tail cone assembly often contains major components of various systems, including hydraulics, ambient, electrical distribution, flight controls, engine fire suppression, and external toilets. The baggage compartment is also often located in the tail cone, where external access to both the equipment and the baggage compartment is required to allow maintenance via external removable panels, as well as baggage compartment doors, which meet high certification standards.
These prefabricated aviation tail cone structures are matched to meet energy transfer requirements through various load paths. There may also be replacement structures designed as part of the metal airframe, where metal joining techniques, rather than traditional assembly, are used to further reduce weight and durability if required. Weight savings can also be achieved in acceptable applications with parts made of composite materials. This section describes typical repairs to major structural parts of the aircraft. When repairing a damaged component or part, consult the appropriate section of the aircraft manufacturer's SRM. Usually a similar repair is illustrated and the types of materials, rivets and rivet spacing, methods and procedures to be used are given. All the additional knowledge needed for the repair are also detailed. If the required information is not found in the SRM, try to find a repair or similar assembly installed by the aircraft manufacturer.
Floats To maintain the float in an airworthy condition, periodic and frequent inspections are required due to the corrosion rate of metal parts, especially when the aircraft is operated in salt water. Inspection of floats and hulls includes examining for damage due to corrosion, collision with other objects, hard bottoms, and other conditions that can lead to failure.
Sheet metal panels should be repaired using approved practices; however, the joints between the sheet metal parts must be waterproofed with a suitable fabric and sealant. A float undergoing hull repair should be tested by filling it with water and letting it sit for at least 24 hours to see if there are any leaks. [Figure 1]
Sheet Metal Fabrication, Inspection And Repair Level 2
Some of the smaller general aviation aircraft flight controls have beads in their panels. The beads lend a certain stiffness to the thin sheets of leather. The repair beads can be formed using a rotary die or press. [Figure 2]
Panel Replacement Damage to the aircraft's metal skin that exceeds repairable limits requires replacement of the entire panel. [Figure 3] The plate also needs to be replaced when there are too many previous repairs in a given part or area.
In aircraft construction, a panel is a single sheet of metal skin. A panel section is the part of the panel between adjacent stringers and bulkheads. When a piece of leather is damaged to the point where it is impossible to incorporate a standard leather repair, a special type of repair is required. The specific type of repair required depends on whether the damage can be repaired on the outside of the member, inside the member, or at the edges of the slab.
Outer Member For damage of 8½ diameter rivets or more material after cutting, extend the patch to include the manufacturer's row of rivets and add an additional row inside members.
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Inner Member For damages that after trimming are less than 8½ the manufacturer's rivet diameter within the members, use a patch that extends through the members and an additional row of rivets along the outside of the members.
Panel Edges For damage extending to the edge of the panel, use only one row of rivets along the edge of the panel, unless the manufacturer has used more than one row. The procedure for repairing the other edges of the damage follows the methods previously explained.
The procedures for all three types of panel repair are similar. Cut the damaged part to the tolerances specified in the previous paragraphs. To relieve stress on trim corners, round them to a minimum ½-inch radius. Place a new row of rivets with a cross pitch of approximately five rivet diameters and offset the rivets with those set by the manufacturer. Cut the seam plate from material of the same thickness as the original or a later thicker thickness, leaving a gap between the edges of 2½ diameters of the rivet. At the corners, draw arcs whose radius is equal to the distance from the edge.
Chamfer the edges of the splice plate to a 45° angle and shape the plate to match the contour of the original structure. Tuck the edges down a bit so they fit snugly. Place the seam plate in the correct position, drill a hole for the rivets and temporarily secure the seam plate in place with fasteners. Using the hole finder, locate the location of the second hole, drill it and insert the second fastener. Then, from the back and through the original holes, locate and drill the remaining holes. Deburr rivet holes and apply corrosion inhibitor to mating surfaces before riveting patch in place.
U.s. Navy Aviation Structural Mechanic Careers
Lighting Hole Repair As mentioned earlier, lighting holes are cut into rib sections, fuselage frames, and other structural parts to reduce part weight. The holes are lined to make the mesh stronger. Cracks can develop around the flanged light holes and these cracks should be repaired with a repair plate. The damaged area (fissure) must be blocked by drilling or the damage must be removed. The repair plate is made of the same material and thickness as the damaged part. The rivets are the same as the surrounding structure and the minimum edge is 2 times the diameter and the distance between them is four to six times the diameter. Figure 4 illustrates a typical lightning repair.
Pressure Zone Repairs The skin of a pressurized aircraft is highly stressed during flight. Pressure cycles place stress on the skin, and repairing this type of structure requires more rivets than repairing skin without pressure. [Figure 5]
Crossbar repair. Spars run from the nose of the aircraft to the tail, and wing spars run from the fuselage to the wingtip. Control surface stringers usually extend the length of the control surface. The skin of the fuselage, wings or control surface is attached with rivets.
Traverses can be damaged by vibration, corrosion or impact. Because crossmembers come in many different shapes, repair procedures vary. The repair may require the use of preformed or extruded repair material, or it may require material made by an airframe technician. Some repairs may require both types of repair materials. When repairing a bolt, first determine the extent of the damage and remove the rivets from the surrounding area. [Figure 6] Then remove the damaged area using a hacksaw, wrench, drill or file. In most cases, support repair requires the use of an insert and joint angle. When locating the transom angle during repair, be sure to consult the appropriate structural repair manual for the location of the repair piece. Some battens are repaired by installing a joint angle on the inside, while others are repaired by installing it on the outside.
California National Guard Makes Historic Gray Eagle Repairs > National Guard > Article View
Extrusions and preformed materials are commonly used to repair corners and inserts or fillers. If the repair corners and fills are to be formed from flat sheet metal, use a brake. You may need to use bend margins and sight lines when creating layouts and bends for these formed parts. For bent string repairs, have the repair parts match the original outline.
Figure 7 shows string repair via patch. This repair is permitted when the damage is no more than two-thirds of the width of a leg and no longer than 12 inches. Damage exceeding these limits can be repaired
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