Service and Repair Manual

the shank. Care should be exercised not to elongate the rivet hole. See this section, paragraph 19. for information concerning enlarged rivet holes. After the removal of the rivet, inspect the hole to see that particles of metal are not lodged between the sheets holding them apart.

9. Removal of Countersunk Head Rivets.

     The same procedure as followed in this section, paragraph 8., is a good method, except that a center mark should be made on the center of the rivet head before proceeding to drill. Use a drill of the same size or slightly smaller than the rivet shank. Drill into the head of the rivet to half the thickness of the nearest plate or sheet. The head should come away on the drill in the form of a washer. If this does not happen the remainder of the rivet may be punched out with a flat-ended pin punch small enough to pass through the hole.

10. Fitting Solid Rivets.

     a. Replacing Solid Rivets. - Solid rivets maybe replaced by several methods. Press countersunk 100 degree rivets are used extensively on skin gage .051 inch and under. For skin over .051 inch, drill countersunk 100-degree rivets are used. Drill countersunk rivets should never be used on sheets under .051 inch. All rivets should be a good fit in their holes. When press countersinking the sheet for a 5/32-inch rivet first drill with an 1/8-inch drill and then form with a male and female steel die. The hole is then re drilled using a No. 22 (.157-inch) drill and the rivet is inserted and driven by hand with a moderate weight hammer.

     b. Skin Countersinking. - Drill counter sinklng of the sheet offers less support against shearing of the rivet than does the press countersunk sheet. In the fabrication of drill countersunk rivets, care must be taken to be sure that the head of the. rivet is flush with the surface. If the drill countersink is allowed to go too deep, the joint is weakened.

     c. Riveting Operations. - For rivet operations, insert the rivet from the outside, place the heading tool on the rivet head, and drive the rivet. The blow should he shocked on the inside~by a dolly whose distance from the member will become less as the body of the rivet becomes shorter. The counterblock of the dolly should be adjusted during clinching and head forming. Uniform and straight driving of the rivet and if body will be difficult unless the dolly is in the exact center of the rivet. Caution should be taken that the rivet does not fit too tightly as it will cause the plates to bulge, and when the rivet is not pulled tight, clinches will be formed between the plates. Also avoid closing the head too flat. Avoid material buckling of the skin due to an apparent "bulge" between the press countersinks. See figure 3. for flush riveting tools.

     d. Effecting Repairs on Wing Skin.

When effecting repairs on the wing skin, flush-type doors are recommended, because of structural value and also for access ln locating any future damage that may occur on or around the vicinity. (See section VI, paragraph 3.a.(2).)

11. Rivet Allowance - Modified Brazier Head Rivet (671-D).

For 1/8-inch diameter rivet: The formed head thickness should be .047 inch the diameter of the formed head should be .156 inch the extruded length of the rivet, after insertion, should be 5/32 inch.

For 5/32-inch diameter rivet: The formed head thickness should be .063 inch the diameter of the formed head should be .203 inch the extruded length of the rivet, alter insertion should be 5/32 inch.

For 3/ 16-inch diameter rivet: The formed head thickness should be .078 inch the diameter of the formed head should be .234 inch the extruded length of the rivet, after insertion, should be 3/16 inch. (See figure 4.)

12.Countersunk 78-Degre Rivet (673-D).

For 1/8-inch diameter rivet: The formed head thickness should be .064 inch the diameter of the formed head should be .188 inch the extruded length of the rivet, after insertion, should be 3/16 inch the protrusion due to the press counter sinking of the metal sheets should be 1/32 inch.

For 5/32-inch diameter rivet: The formed head thickness should be .063 inch the diameter of the formed head should be .234 inch the extruded length of the rivet, after insertion, should be 3/16 inch the protrusion due to the press countersinking of the metal sheets should be 5/64 inch.

For 3/16-inch diameter rivet: The formed head thickness should be .078 inch the diameter of the formed head should be .281 inch the extruded length of the rivet, after insertion, should be 3/16 inch the protrusion due to the press counter sinking of the metal sheets should be 1/16 inch. (See figure 4.)

13. Countersunk 100-Degree Rivet (AN426).

For 1/8-inch diameter rivet: The, formed head thickness should be .063 inch the diameter of the formed head should be .188 inch the extruded length of the rivet, after insertion, should be 3/16 inch.

For 5/32-inch diameter rivet: The formed head thickness should be .078 inch the diameter of the formed head should be .234 inch the extruded length of the rivet, after insertion, should be 15/64 inch.

For 3/16-inch diameter rivet: The formed head thickness should be .094 inch the diameter of the formed head should be .281 inch the extruded length of the rivet, after insertion, should be 9/32 inch.