Edge distance- distance from center of rivet to the edge of material (2xD to 4XD)

Limits for pitch (3D to 12D) regardless of how many rows.

Transverse pitch or gage in any type overlap is generally 75% of pitch.

3x thickest sheet is the rule to find rivet diameter.

Length of repair, metal thickness, alloy, rivet diameter determine how many rivets are to
be used AC43:131B chart.

Never use a scribe when laying out metal. Scoring of the metal can lead to cracking.

A light coat of Zinc Chromate primer can help with laying out meatal so you can see
your marks easier.

Always check your SRM (Structural Repair Manual) before you start your repair the
manual will have examples of repairs that can be done for a particular damage.

Edge distance is 2xdiameter to 4x diameter

Setback for 90 degrees is Bend Radios + metal thickness

Neutral axis is 46.6 % of the metal thickness that is not affected by starching or
shrinking of the metal while being bent.

Setback for other than 90 degrees is K(BR+MT)

The Empirical formula is used to find Bend Allowance ((.0078 X MT) +( .01743 X BR)) X
each degree of bent through.

Sight line is found by adding one bend radius to the flat coming out of the break.
Imagine that the piece is in the break already and is ready to be bent.

Minimum Bend Radius is the smallest you can bend a particular type of metal without
cracking.

Bend tangent line is where the flat ends and the bend begins.
The best possible bend is always 90 degrees or perpendicular to the grain of the metal.

When bending metal there are 4 main things to consider MT, BR, temper, grain of the
metal.

Pieces to be bent up are called flats and pieces that are already bent are called flanges,
unless one is longer than the other and then that is called the leg.

Sight line is used to line the meatal up to be bent in the break.

The strongest bend is always 90 degrees to the grain or perpendicular to the grain.

A relief hole is used to prevent cracking while bending.

Grain direction can be detected visually by observing the lines on the metal or by the
stenciling. The stenciling goes the same direction as the grain.

Sizing up repair: type of repair, size of repair, number of rivets, MT, type of material and
negligible weight change.
Damage is classified by the extent of the damage.

Surface repair is considered temporary and use protruding head rivets (470)

Flush repairs are considered permanent and use countersunk rivets. (426)

Always form metal before drilling it will elongate the holes.

Any type of forming; you want to use dead soft material or 2024-O or 7075-O or 5056-O
and then heat treat afterwards.

When forming material or doing any type of repair it is important to know material type
and temper.

There are 3 layouts. The bend radius chart is provided in the test. They are all 90
degree bends with only one bend. Make sure to do the layouts on the back of the
bubble sheet this will help you answer the last three questions. The layout are
worth 18 points.