AMT – 110 Sheet Metal

AMT – 110 Sheet Metal Herb Spenner Introduc8on •  Herb Spenner –  herbspenner@gmail.com –  (408) 314-­‐1610 •  Guidelines –  Gavilan College –  FAA Class Requirements •  AC 43-­‐1B/2B •  AC 65-­‐15 •  Op8onal – ASA Test Guides and SoQware –  General and Airframe Test Guide books –  Prepware soQware •  Safety –  Glass –  Ear plugs –  Gloves –  Cloths Class Room Tools • 
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Calculator Machinist's Ruler (1/32, 1/64,1/100) Compass Right angle or triangle Op8onal –  Graph paper –  Computer •  Text books and handout available in “soQ copy” Shop Tools •  No stress risers –  Envelop example –  M&M Test –  Use the correct tool •  Drill bits – 5 each –  #40 bit – 0.98” -­‐ #3 rivet – 3/32” – 0.09375” –  #30 bit – 0.1285” -­‐ #4 rivet – 4/32” (1/8”) – 0.125” –  #21 bit – 0.159” -­‐ #5 rivet – 5/32” – 0.15625” •  Center punch –  Automa8c -­‐ best Shop Tools • 
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Sharpie -­‐ Ultra Fine – (no pencil for marking) File Scrape of wood Op8onal –  Rivet Gauges –  Old dill bit – deburring –  Clamps –  Rive8ng tape –  Caliper or Micrometer –  www.aircraQspruce.com & www.yardstore.com Let’s Do Some Math Rivets •  Start reading AC65-­‐15 – Chapter 5 -­‐ AircraQ Structural Repairs -­‐ page 127 –  Repairs must maintain the original strength of the structure. •  Pop, “Cherry”, Solid •  Solid Rivet Heads –  Fig 3.1 –  Universal -­‐ AN470 (MS20470) –  100° Countersunk – AN426 (MS20426) – flush Rivet Heads Rivet Squeezer Rivet Gun Rivet Gun Rivet Gun Process • 
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Select set Select and install set retainer (spring) Adjust regulator Test regulator adjustment on wood –  Never shoot gun with no load/in the air •  Test on a sample Solid Rivet Material • 
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A – 1100 – Pure aluminum B – 5056 -­‐ Magnesium AD – 2117 – Most common type D – 2017 – “Ice box” DD – 2024 – “Ice box” Rivet Material Rivet Dimensioning •  Diameter is in 1/32’s –  #3 – 3/32, #4-­‐ 4/32 (1/8), #5-­‐ 5/32 •  Length is in 1/16 –  AN470 – shaQ length –  AN426 – full rivet length Rivet Designa8on •  (Head Type) (Material) (Diameter in 1/32s) – (Length in 1/16’s) •  Universal head, 2117, 3/32 diameter, 5/16 length –  AN470AD3-­‐5 or MS20470AD3-­‐5 •  Countersunk head, 1100, 1/8 (4/32) diameter, 1/2 (8/16) length –  AN426A4-­‐8 or MS20426A4-­‐8 Drill Sizes •  #3 – 3/32 -­‐ #40 drill •  #4 – 1/8 (4/32) -­‐ #30 drill •  #5 – 5/32 -­‐ #21 drill Shop Head Dimensions • 
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D – Rivet diameter 1/2 D – Height 1 1/2 – Wide Fig 3.3 Rivet Diameter •  D – At least 3X the thickest sheet –  or what the aircraQ manufacturer used –  Remember to convert to 1/32s •  D ≥ 3 X sheet thickness X 32 (conver8ng to 1/32s) •  Sheet thickness -­‐ 0.025 –  D = 3 X 0.025 X 32 = 2.4 -­‐> 3 •  Sheet thickness – 0.032 –  D = 3 X 0.032 X 32 = 3.072 -­‐> 4 •  Sheet thickness – 0.040 –  D = 3 X 0.040 X 32 = 3.84 -­‐> 4 Rivet Length •  Length = 1.5 X D + Total thickness of all sheets •  Length = (1.5 X D + Sheet 1 + Sheet 2. . .) X 16 –  X 16 is to convert to 1/16s –  Remember to add all the sheets Rivet Length •  2 Sheets of 0.025 – 3/32 rivet –  (1.5 X 3/32 + 0.025 + 0.025) X 16 = 3.05 -­‐> 4 –  AN470AD3-­‐4 or AN426AD3-­‐4 •  2 Sheets of 0.032 – 1/8 rivet (4/32) –  (1.5 X 1/8+ 0.032 + 0.032) X 16 = 4.024 -­‐> 4 or 5 –  AN470AD4-­‐5 or AN426AD4-­‐5 •  2 Sheets of 0.040 – 1/8 rivet (4/32) –  (1.5 X 1/8+ 0.040 + 0.040) X 16 = 4.28 -­‐> 5 –  AN470AD4-­‐5 or AN426AD4-­‐5 Rivet Length •  3 Sheets of 0.025 – 3/32 rivet –  (1.5 X 3/32 + 0.025 + 0.025 + 0.025) X 16 = 3.45-­‐> 4 –  AN470AD3-­‐4 or AN426AD3-­‐4 •  Three sheets -­‐ 0.025, 0.032 and 0.040 sheets –  #4 rivet because of 0.040 –  (1.5 X 1/8 + 0.025 + 0.032 + 0.040) X 16 = 4.552-­‐> 5 –  AN470AD4-­‐5 or AN426AD4-­‐5 Rivet Dimensions •  D – At least 3X the thickest sheet –  or what the aircraQ manufacturer used –  Remember to convert to 1/32s •  D ≥ 3 X sheet thickness X 32 (conver8ng to 1/32s) •  Length = 1.5 X D + Total thickness of all sheets –  Remember to convert to 1/16s •  Length = (1.5 X D + Sheet 1 + Sheet 2 . . .) X 16 –  X 16 is to convert to 1/16s –  Remember to add all the sheets Rivet Spacing •  Distance is measured from the center of the rivet •  Edge distance – 2 to 4 D •  Distance between rivets 3 to 10 D per AC43.13-­‐1B –  Handout says 3 to 12 Read AC43-­‐13.1B Par 4-­‐57 Rive8ng Rivet Plates • 
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4” X 6” #3, #4 and #5 rivet plates 2D edge distance 6” direc8on – about 6D 4” direc8on – about 75% of 6” Get paper design approved –  Show math Rivet Plate -­‐ #4 •  D = 1/8” = 0.125 •  6” side –  Distance between first and last •  6 – 2D – 2D = 6 – 4D •  6 – 4 * 0.125 = 5.5 –  Rivet spacing is about 6D or 0.75 •  5.5 /0.75 = 7.3333 (use 7) •  5.5 / 7 = 0.7857 = ~ 25.1/32 Rivet Plate -­‐ #4 •  4” side –  Distance between first and last •  4 – 2D – 2D = 4 – 4D •  4 – 4 * 0.125 = 3.5 –  Rivet spacing is about 75% of 0.7857 •  0.7857 X 75% = 0.5893 •  3.5 / 0.5893 = 5.9392 (use 6) •  3.5 / 6 = 0.5833 = ~18.6/32 Rivet Plate -­‐ #4 Remaining Topics • 
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Aluminum sheet metal proper8es Bending Patch design Sheet metal fasteners Flush rive8ng Aluminum Sheet Metal Strength • 
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Alloys (e.g. 1100, 2024 & 6061) Treatment/tempering Thickness Shape Look at 43.12-­‐1B Page 4-­‐8 Table 4-­‐5 Aluminum Sheet Hardness Temper •  Work hardening –  Work hardening –  Cold hardening –  Strain hardening •  Heat trea8ng/hardening •  Age hardening •  Look at 43.12-­‐1B Page 4-­‐4 Metal Bending Layout Procedure 1.  Determine stock size or “where to cut” 2.  Locate brake reference lines or “where to bend” 3.  Mark centers or “where to drill” Radius Bending Brake Bending Brake Bending Brake Bend Radius Neutral Line Bend Defini8ons •  MLD – Mold Line Dimension – the length of the side from the edge to the center of a perfect bend (0 radius) •  BTLD – Bend Tangent Line Dimension – the length of the side from the edge to the beginning of the bend •  BA – Bend Allowance – The area that will be bent •  Developed Width – Length of the material used to make bracket Bend Set Back •  SB – Set Back – the difference between the Mold Line Distance and Bend Tangent Line Dimension –  SB = MLD – BTLD Brake Reference •  Brake Reference (Line) – The line were the brake is lined up Open Angle •  Open Angle – Bent less than 90° Page 3-19
Closed Angle •  Closed Angle – Bent greater than 90° Non 90° Angles •  Set Back – K * (T + R) –  K is found 5-­‐25A page 150 in AC 65-­‐15 •  Bend Allowance: # of degrees * small number in 5-­‐24 page 149 in AC 65-­‐15 Countersinking From
AC65-15
Countersinking Countersink Microstop Countersink Cage Dimple Dimple Also called a “nest” or “well”
Dimple Set Dimple Set Dimple Tool Dimple Tools Dimple Tools Dimple Tools Cold Dimpling •  If possible use a smaller drill size –  Die can stretch the rivet hole •  Don’t cold dimple hard metal •  Coin dimpling –  Using a rivet as the male die –  Use a “normal” female die in special bucking bar –  “Buck” dimple –  Hard to reach places Thermal Dimple Tools Thermal Dimpling •  Heated dies •  Use for hard metals –  Reduces changes of cracking –  7075-­‐T6, magnesium or 8tanium •  Radius –  Solid female die •  Coin –  Sliding ram female die –  Forms a more uniform dimple (nest or well) Thermal Dimpling Countersink/Dimple Flush Rivet Guidelines Patching Skin Damage •  Stop drill cracks or cut out damage. –  Leave no stress risers – no sharp corners •  Calculate the number of rivets •  Make a paper design of a patch –  Mark holes to insure no interference •  Create a patch –  Same material and same thickness or greater –  Patch will go under skin if possible Patching Skin Damage • 
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Make filler plug if needed Drill holes Apply corrosion inhibitor/primer Rivet Prime and Paint Stop Drill Rivet Spacing •  Rivet pitch -­‐ the distance between the centers of adjacent rivets in the same row. –  Minimum – 3D; Maximum – 10D –  Typical 6D to 8D •  Transverse pitch -­‐ the perpendicular distance between rivet rows –  75% of rivet pitch –  Minimum – 2 1/2D •  Edge Distance – 2D to 4D Rivet Spacing Rivet Spacing Elongated Octagonal Patch AC65-15
Fig. 5-74
Page 190
Elongated Octagonal Patch Round Patch AC65-15
Fig. 5-76
Page 191
Turn Down Edge AC65-15
Fig. 5-77
Page 192
Panel Repair AC65-15
Fig. 5-78
Page 192
Patch Ideas AC43.13
Fig. 1-15
Page 1-29
Patch Ideas AC43.13
Fig. 1-17
Page 1-32
Your Guides •  Follow manufacturer’s instruc8ons –  Maintenance/Repair manual –  Copy hole rivet payern –  Use same material and rivets •  Use AC43.13-­‐1B Par 4-­‐58 •  Read AC65-­‐15 189-­‐198 Number of Rivets When any kind of repair to an aircraft structure
is made. the basic requirement is to restore all
of the strength that has been lost. There must
be enough rivets on one side of the damage to
carry all of the required stresses into the patch,
with enough rivets on the opposite side to put
the stresses back into the skin.
Number of Rivets -­‐ AC65-­‐15 •  # Rivets = Length of Crack X Thickness of Metal ÷ Shear Strength •  N = L X T / Shear Strength •  Book says Shear or Bearing strength, which ever is less –  A good joint should be based on Shear strength •  User fig 5-­‐1 for Shear strength or fig 5-­‐2 for Bearing strength (page 128 or 129) Number of Rivets – AC43.13-­‐1B •  Use Tables 4-­‐9, 4-­‐10 or 4-­‐11 for rivets per inch. –  Page 4-­‐37, 4-­‐38 or 4-­‐39 •  # Rivets = Length of crack X Rivets per inch •  # Rivets is only for one side. •  The rivet used is 2 X # Rivets Crack Patch Blind Rivets •  Also called “Mechanically Expanded Rivet” •  Installed by “pulling” on rivet stem –  Installed with a “pulling tool” –  “Blind Rivet” – need to access only on side –  No hammering •  Used with some plas8cs and plywood •  Nonstructural –  “Pop” rivet –  Stem doesn’t add strength –  Commonly used for engine baffling and interiors Structural Rivets •  “Cherry” Rivets •  Cherrylock or Huck •  ShaQ mechanically locks inside rivet and creates the strength of the rivet •  Cherry “2000” – one size larger than solid rivet •  CherryMax or “3000” – same size as solid rivet –  Only blind rivet interchangeable structurally with solid rivets •  hyp://www.cherryaerospace.com/images/
anima8ons/cherrymax/CherryMax_100MS.swf Structural Rivets Dimension •  Diameter in 1/32s –  Also available in oversize – 1/64 over •  Length in 1/16s –  Also specified in grip length •  Rivet specified like solid rivets –  e.g. 4-­‐3 or 5-­‐4 Structural Rivets Grip Structural Rivets Heads Remove Blind Rivet Hi-­‐Shear • 
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Same strength as a bolt Less labor to install than a bolt Lighter than a bolt Needs very specialized tools Hi-­‐Lok •  Like Hi-­‐Shear but can be installed with standard tools –  Allen wrench and socket/box wrench Turnlock Fasteners • 
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Ayach inspec8on panels, cowls, and fairings Self contained hardware Half turn on or off Limited shear and bearing strength Dzus Camloc Airloc Nutplates Rivnut AircraQ Structures Truss-­‐Type Fuselage Tube/Fabric Fuselage Monocoque/Semi-­‐monocoque Semi-­‐monocoque Fuselage Semi-­‐monocoque Fuselage Loca8on Designa8ons Loca8on Designa8ons •  Fuselage Sta;ons – numbered in inches from a reference or zero point know as the reference datum. (length wise) •  Bu=ock Line (buy line) – width measurement leQ or right of, and parallel to, the ver8cal center line. (width wise) •  Water Line – the measurement of height in inches perpendicular from a horizontal plane located a fixed number of inches below the boyom of the aircraQ fuselage (high wise) Wing Shapes Wing Posi8ons Can8levered Wing Cantilevered
Non-Cantilevered
Dihedral
Support Strut
Wing Sta8ons •  Wing Sta;on – wing sta8on 0 (zero) is located at the center line of the fuselage, and all wing sta8ons are measured outboard from the point, in inches Wing Structure Empennage Stabilator Ruddervators Engine Compartment Spinner
Engine Mount
Helicopter Components Aerodynamics All About Forces Air •  Air acts like a fluid (sub-­‐sonic) –  Has weight –  Flows •  Has Pressure –  Decrease with al8tude –  Changes with weather •  Density –  Directly related to pressure –  Inversely related to temperature –  Inversely related to humidity (water vapor weighs 5/8 of air) Drag Drag •  Drag is the fric8on caused by air flowing around the aircraQ •  Induced Drag – the drag created by genera8ng liQ. •  Parasi8c Drag – the total drag minus the induced drag –  Form drag –  Skin fric8on –  Interference drag Drag Bernoulli’s Principle •  Velocity goes up/Pressure goes down –  For subsonic –  Conserva8on of energy Bernoulli’s Principle Wing Terminology LiQ – Bernoulli's Principle LiQ – Angle of Ayack Stall Stall Center of Pressure Center of Pressure Axes of an AircraQ Primary Flight Controls Ailerons Adverse Yaw Use Rudder to Correct Yaw “Step on the Ball” Differen8al Ailerons •  The down going aileron moves less than the up going aileron –  Goal is to reduce adverse yaw Elevator Rudder Secondary Control Surfaces • 
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Also known as Auxiliary Control Surfaces Tabs Trailing Edge Flaps Leading Edge Flaps Spoilers Speed Brakes Purposes –  Reduce primary control forces –  Reduce land/takeoff speed or length –  Change aircraQ speed Tab •  Used to move control surface •  Tab forces control surfaces in the opposite direc8on –  e.g. up facing tab forces control surface down Trim Tab •  Enables the pilot to make adjustments from the cockpit Servo Tab •  Acts like power assist •  Tab is used to move flight control Spring Tab • 
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Spring is used to help link tab movement Acts like power assist Has more effect at high control forces Several different spring configura8ons Balance Tab •  Acts like power assist •  Tab is linked to fixed spot An8-­‐Servo Tab •  Acts against the pilots ac8ons •  Helps add stability to a control An8-­‐Servo Tab Ground Adjustable Tab Adjustable Surface Flap • 
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Increase liQ Used at slow speed Increased drag Moves center of pressure aQ on the airfoil –  Causes a nose-­‐down pitching moment Flap Plain Flap Split Flap Sloyed Flap Fowler Flap •  Only flap type that increases the wing size Fowler Flap Leading Edge Slot Leading Edge Slat Leading Edge Flap Spoiler Spoiler Speed Brake FAA Ques8ons Ques8on 8042 •  A main difference between Lockbolt/Huckbolt tension and shear fasteners (other than their applica8on) is in the –  a. number of locking collar grooves. –  b. shape of the head. –  c. method of installa8on –  Answer -­‐ A Ques8on 8046 •  One of the main advantages of Hi-­‐Lok type fasteners over earlier genera8ons is that –  a. they can be removed and reused again. –  b. the squeezed on collar installa8on provides a more secure, 8ghter fit. –  c. they can be installed with ordinary hand tools. –  Answer -­‐ C Ques8on 8047 •  The markings on the head of a Dzus fastener iden8fy the –  a. body diameter, type of head, and length of the fastener. –  b. body type, head diameter, and type of material. –  c. manufacturer and type of material. –  Answer -­‐ A Ques8on 8048 •  The Dzus turnlock fastener consists of a stud, grommet, and receptacle. The stud length is measured in –  a. hundredths of an inch. –  b. tenths of an inch. –  c. sixteenths of an inch. –  Answer -­‐ A Ques8on 8049 •  The Dzus turnlock fastener consists of a stud, grommet, and receptacle. The stud diameter is measured in –  a. hundredths of an inch. –  b. tenths of an inch. –  c. sixteenths of an inch. –  Answer -­‐ C Ques8on 8102 •  Longitudinal (fore and aQ) structural members of a semi-­‐monocoque fuselage are called –  a. spars and ribs. –  b. longerons and stringers. –  c. spars and stringers –  Answer -­‐ B Ques8on 8103 •  Shallow scratches in sheet metal may be repaired by –  a. burnishing. –  b. buffing. –  c. stop drilling –  Answer -­‐ A Ques8on 8104 •  What should be the included angle of a twist drill for soQ metals? –  a. 118° –  b. 90° –  c. 65° –  Answer -­‐ B Ques8on 8105 •  When comparing the machining techniques for stainless steel sheet material to those for aluminum alloy sheet, it is normally considered good prac8ce to drill the stainless steel at a –  a. higher speed with less pressure applied to the drill –  b. lower speed with more pressure applied to the drill –  c. lower speed with less pressure applied to the drill –  Answer -­‐ B Ques8on 8107 •  Which statement is true regarding the inspec8on of a stressed skin metal wing assembly known to have been cri8cally loaded? –  a. If rivets show no visible distor8on, further inves8ga8on is unnecessary –  b. If bearing failure has occurred, the rivet shanks will be joggled –  c. If genuine rivet 8pping has occurred, groups of consecu8ve rivet heads will be 8pped in the same direc8on –  Answer -­‐ C Ques8on 8109 •  When drilling stainless steel, the drill used should have an included angle of –  a. 90° and turn at a low speed. –  b. 118° and turn at a high speed. –  c. 140° and turn at a low speed. –  Answer -­‐ C Ques8on 8124 •  The monocoque fuselage relies largely on the strength of –  a. longerons and formers –  b. skin or covering –  c. bulkheads and longerons –  Answer -­‐ B Ques8on 8125 •  Which part(s) of a semi-­‐monocoque fuselage prevent(s) tension and compression from bending the fuselage? –  a. The fuselage covering. –  b. Longerons and stringers. –  c. Bulkheads and skin. –  Answer -­‐ B Ques8on 8147 •  Mild steel rivets are used for rive8ng –  a. nickel-­‐steel parts. –  b. magnesium parts. –  c. steel parts. –  Answer -­‐ C Ques8on 8149 •  When rive8ng dissimilar metals together, what precau8ons must be taken to prevent an electroly8c ac8on? –  a. Treat the surfaces to be riveted together with a process called anodic treatment. –  b. Place a protec8ve separator between areas of poten8al electrical difference. –  c. Avoid the use of dissimilar metals by redesigning the unit according to the recommenda8ons outlined in AC 43.13-­‐1A. –  Answer -­‐ B Ques8on 8152 •  Joggles in removed rivet shanks would indicate par8al –  a. bearing failure. –  b. torsion failure. –  c. shear failure. –  Answer -­‐ C Ques8on 8154 •  Which rivet is used for rive8ng magnesium alloy structures? –  a. Mild steel –  b. 5056 aluminum –  c. Monel –  Answer -­‐ B Ques8on 8155 •  Which rivet is used for rive8ng nickel-­‐steel alloys? –  a. 2024 aluminum. –  b. Mild steel. –  c. Monel. –  Answer -­‐ C Ques8on 8161 •  If a streamline cover plate is to be hand formed using a form block, a piece of dead soQ aluminum should first be placed over the hollow por8on of the mold and securely fastened in place. The bumping opera8on should be –  a. distributed evenly over the face of the aluminum at all 8mes rather than being started at the edges or center. –  b. started by tapping the aluminum lightly around the edges and gradually working down into the center. –  c. started by tapping the aluminum in the center un8l it touches the boyom of the mold and then working out in all direc8ons. –  Answer -­‐ B Ques8on 8165 •  If it is necessary to compute a bend allowance problem and bend allowance tables are not available, the neutral axis of the bend can be –  a. represented by the actual length of the required material for the bend. –  b. found by adding approximately one-­‐half of the stock thickness to the bend radius. –  c. found by subtrac8ng the stock thickness from the bend radius. –  Answer -­‐ B Ques8on 8171 •  The purpose of a joggle is to –  a. allow clearance for a sheet or an extrusion –  b. increase obstruc8on for a sheet or an extrusion –  c. decrease the weight of the part and s8ll retain the necessary strength –  Answer -­‐ A Relief Holes