Sheet Metal Structural Repair Flashcards

When performing a flush patch repair on aircraft skin, the patch must overlap the damaged area by at least how many rows of rivets?

Answer: Two rows

A flush patch must overlap the damage by at least two rows of rivets to restore original strength.

What is the primary purpose of a joggle in sheet metal repair?

Answer: To allow overlapping sheets to lie flush without a step

A joggle is an offset formed in sheet metal to allow two overlapping pieces to remain flush on the surface.

Which type of rivet is most commonly used in aircraft sheet metal repairs to original structure?

Answer: MS20470 (AN470) universal head

The MS20470 (AN470) universal head rivet is the most widely used rivet for general aircraft sheet metal repairs.

What is the minimum edge distance for a rivet in a sheet metal repair?

Answer: 2D (2 times the rivet diameter)

Minimum edge distance for rivets is 2D (twice the rivet diameter) measured from the center of the rivet to the edge of the sheet.

When selecting replacement rivets for a sheet metal repair, you find the original rivets are 2117-T4. What is the primary advantage of this rivet material?

Answer: It can be driven in the as-received condition without heat treatment

2117-T4 (AD) rivets are field-ready because they do not require refrigeration or re-heat treatment before driving.

What ratio is used to determine the correct rivet diameter for a sheet metal repair based on the thickness of the thickest sheet being joined?

Answer: 3 times the sheet thickness

Rivet diameter should be approximately 3 times the thickness of the thickest sheet being joined.

When drilling out a rivet for removal, the drill bit should be the same diameter as:

Answer: The rivet shank

When removing a rivet, the drill is sized to match the shank diameter to drill out the head without enlarging the hole.