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AIRFRAME ORALS
CHAPTER 2 - SHEET METAL STRUCTURES
Question | Answer |
---|---|
WHAT IS THE MAJOR TYPE OF DAMAGE TO ALUMINUM STRUCTURES THAT IS CAUSED BY EXPOSURE TO THE WEATHER? | CORROSION |
NAME SEVERAL METHODS FOR FORMING SHEET METAL. | BENDING/FOLDING, STRETCHING, SHRINKING, BUMPING, AND CRIMPING. |
WHAT ARE THE DIMENSIONS OF A PROPERLY FORMED RIVET HEAD? | THE HEAD SHOULD BE 1 1/2 TIMES THE SHANK DIAMETER IN WIDTH AND 1/2 THE SHANK DIAMETER IN HEIGHT. |
DESCRIBE THE MARKINGS FOUND ON THE HEADS OF A, B, D, AD, AND DD RIVETS. | A RIVETS ARE PLAIN, B RIVETS HAVE A CROSS, D RIVETS HAVE A RAISED DOT, AD RIVETS HAVE A DIMPLE AND DD RIVETS HAVE A DOUBLE DASH. |
WHAT HAPPENS TO THE STEM OF A SELF-PLUGGING (FRICTION LOCK) RIVET WHEN THE RIVET IS INSTALLED? | THE STEM IS PULLED UNTIL IT SNAPS OFF AND THE REMAINING PROJECTING PART IS TRIMMED FLUSH WITH THE HEAD. |
NAME AT LEAST THREE TYPES OF SELF-PLUGGING MECHANICAL LOCK RIVETS. | CHERRYMAX, CHERRYLOCK, OLYMPIC-LOK, AND HUCKLOK RIVETS. |
WHAT IS THE DIFFERENCE BETWEEN THE TOOLS REQUIRED TO PULL A CHERRYLOCK RIVET AND A CHERRYMAX RIVET? | CHERRYLOCK RIVETS REQUIRE A TOOL FOR EACH DIFFERENT SIZE AND HEAD SHAPE, WHILE ONE PULLING TOOL WILL SET ANY SIZE CHERRYMAX RIVET. |
WHICH OF THE FIVE STRESSES IS THE MOST COMMON CAUSE OF RIVET FAILURE? | SHEAR. |
IF A 2024 RIVET MUST BE REPLACED WITH A 2117 RIVET, HOW DO YOU DETERMINE THE SIZE TO BE USED? | FOR 5/32" OR SMALLER DIAMETER, USE THE NEXT LARGER SIZE 2117 RIVET, ASSUMING THAT THE EDGE DISTANCE AND SPACING MEET THE MINIMUM REQUIREMENTS. |
DESCRIBE THE PROCESS FOR DETERMINING THE TOTAL LENGTH OF A SOLID RIVET FOR A PARTICULAR INSTALLATION. | ADD THE GRIP LENGTH (THICKNESS OF THE MATERIALS BEING JOINED) PLUS 1 1/2 TIMES THE RIVET DIAMETER. |
WHAT MINIMUM EDGE DISTANCE AND SPACING SHOULD BE USED FOR A SINGLE ROW OF PROTRUDING HEAD RIVETS? | NOT LESS THAN TWO RIVET DIAMETERS FROM THE EDGE AND NOT LESS THAN THREE RIVET DIAMETERS APART. |
HOW CAN A MECHANIC DETERMINE WHEATHER THE COUNTERSINK FOR A FLUSH RIVET SHOULD BE DIMPLED OR DRILLED? | BY THE THICKNESS OF THE TOP SHEET; THIN SHEETS ARE DIMPLED WHILE THICK SHEETS MAY BE COUNTERSUNK. |
WHAT ACTION IS TAKEN TO PREVENT CRACKS FROM FORMING WHILE DIMPLING MAGNESIUM OR SOME HARD SHEET METALS? | HOT DIMPLING EQUIPMENT IS USED TO PREHEAT AND SOFTEN THE METAL BEFORE THE DIMPLE IS FORMED. |
WHAT TYPE OF DAMAGE CAN OCCUR WHEN USING A RIVET SET THAT DOES NOT PROPERLY FIT THE RIVET? | IF THE RADIUS OF THE SET IS TOO SMALL, THE RIVET HEAD MAY BE DAMAGED, WHEREAS A SET WITH AN OVERSIZED RADIUS MAY CAUSE DAMAGE TO THE SHEET METAL. |
WHY IS IT IMPORTANT TO USE THE PROPER SIZE AND WEIGHT BUCKING BAR WHEN PERFORMING SHEET METAL RIVETING? | IF A BUCKING BAR IS TOO LARGE OR HEAVY IT MAY BE DIFFICULT TO CONTROL AND MAY CAUSE DAMAGE TO THE SURROUNDING STRUCTURE, WHERAS A BUCKING BAR THAT IS TOO LIGHT WILL NOT PROPERLY UPSET THE RIVET BEFORE WORK HARDENING OCCURS. |
WHAT PROCEDURES SHOULD BE FOLLOWED TO PROPERLY REMOVE A SOLID-SHANK RIVET? | CENTER PUNCH THE RIVET, THEN DRILL JUST TO THE BASE OF THE RIVET HEAD WITH SAME SIZE OR ONE SIZE SMALLER DRILL. ONCE DRILLED, USE A PIN PUNCH TO TIP OFF THE RIVET HEAD AND DRIVE THE REMAINING SHANK OUT OF THE HOLE WHILE SUPPORTING THE SURROUNDING METAL. |
WHAT ARE THE TWO SPECIAL CALCULATIONS THAT MUST BE MADE WHEN BENDING SHEET METAL? | BEND ALLOWANCE AND SETBACK. |
WHAT FACTORS MUST BE CONSIDERED IN ORDER TO DETERMINE SETBACK? | THE THICKNESS OF THE METAL AND THE BEND RADIUS. |
WHAT IS DONE TO A CORNER WHERE TWO BENDS INTERSECT TO PREVENT CRACKING? | RELIEF HOLES ARE DRILLED IN THE CORNER. |
WHAT ARE THE TWO REASONS FOR INSTALLING A LIGHTENING HOLE IN A SHEET METAL WING RIB? | LIGHTENING HOLES REDUCE THE WEIGHT AND INCREASE STIFFNESS. |
DESCRIBE A JOGGLE AND EXPLAIN ITS FUNCTION. | A JOGGLE IS AN OFFSET FORMED AT AN INTERSECTION OF TWO OR MORE SHEETS OF METAL TO ALLOW THE MULTIPLE SHEETS TO BE STACKED FLAT AGAINST EACH OTHER. |
WHEN REPAIRING AN ALL-METAL AIRCRAFT, HOW DO YOU DETERMINE WHAT METALS SHOULD BE USED? | ALWAYS USE METAL OF THE SAME TYPE AND THICKNESS AS THE ORIGINAL STRUCTURE. |