TM-9-2320-280-20 HMMWV Technical Manual Unit Maintenance Volume 3 Download
Page 128 of 1170
TM 9-2320-280-20-3 10-66. BODY REPAIR (Cont’d) 1. The damaged area should be thoroughly cleaned and inspected to determine cause and extent of damage. Body parts should be inspected for holes, cracks, dents, distortion, or breaks. Fasteners should be inspected for breaks, stretching, looseness, cocked heads, or hole elongation. Seams, flanges, and joints should be inspected for straightness or local deformation as an indication that fasteners may have been stretched or holes elongated. It is possible for this to happen and fasteners still appear to be tight in their holes. In addition, make thorough inspection of adjacent areas to determine if high loads have been transmitted from the damaged area to other areas. This can result in secondary damage in the form of distorted panels or seams, loosened or sheared fasteners, elongated fastener holes, and cracks. 2. Signs of rivet failure include tipped heads, looseness, and sometimes chipped or cracked paint. If heads are tipped in the same direction and rivets are loose in consecutive groups, the joint has undergone excessive load. Rivet heads which are tipped in different directions and are not in groups may be improperly installed. With chipped or cracked paint, it may be necessary to remove paint to check true condition of rivets. Rivets subjected to critical loads but showing no distortion, should be inspected if failure is suspected. The head should be drilled off, and the shank should be carefully punched out. Failure is indicated by notched rivet shank and misaligned holes. Flush rivets showing head slippage within the dimple or countersink indicate either sheet bearing or rivet shear failure and must be removed for inspection and replacement. If failure of rivets cannot be detected by visual inspection, the joint can be checked by drilling and punching out several rivets. If rivet shanks are notched, rivets should be replaced with next larger size rivets. If rivet holes show elongation due to local failure in tearing of the sheet, next larger size rivet must be used in replacement. Any deformation of the sheet around the rivet, tear outs, or cracks between rivets usually indicates partially failed or damaged rivets. Complete repair of the joint will require replacement by next larger size rivets. Use the next 1/32 inch larger diameter rivet to obtain a tight joint when original hole has been enlarged. If original size rivet is installed, the rivet would not be able to carry its share of the shear load, and the joint would not meet its strength requirement. c. Rivet Replacement NOTE When removing rivets, care should be taken to not enlarge rivet hole as this would require use of an oversize or larger rivet for replacement. 1. Solid Rivet Removal. (a) (b) (c) (d) (e) File a flat surface on the manufactured head if accessible, It is always preferable to work on manufactured head rather than the one that is bucked over, since the former will always be more symmetrical about the shank. Indent center of the filed surface with a center punch. Drill through rivet head. Be sure to use a drill slightly smaller than diameter of rivet shank to avoid making rivet hole oversized. Shear weakened rivet head off with a sharp chisel. For this operation, support back side of rivet and cut rivet head along direction of rivet line or panel edge. This will prevent distortion of the panel. Firmly support the panel from the opposite side and drive out shank with a pin punch. If rivet is unduly tight because of swelling between sheets, drill rivet shank out with an undersize drill. 2. Blind Rivet Removal. (a) File a small flat on rivet head. (b) Center punch the flat. Support rivet backside, if possible. (c) Using a small drill about the size of rivet pin, drill off tapered end of pin which forms the lock. 10-106