Maintenance Practices and Materials Flashcards

Per AC 43.13-1B, what is the minimum diameter of safety wire for general-purpose safetying?

Answer: 0.032 inch

0.032-inch wire is the minimum for general use; 0.020-inch is allowed only for small, closely spaced parts and special cases.

Safety wire must be installed so that any tension on the wire tends to:

Answer: Tighten the fastener

The wire must pull in the tightening direction so the fastener cannot back off.

After tightening a castellated nut to minimum torque, the cotter pin holes do not line up. What is the correct action?

Answer: Tighten further, staying within the specified torque range, until they align

Tighten further within the allowed torque range to align the slot; never back the nut off to align it.

Fiber-insert (non-metallic) self-locking nuts should not be used where temperatures exceed approximately:

Answer: 250°F

Fiber inserts lose their locking ability above about 250°F, so all-metal locknuts are used in hotter areas.

Which aluminum rivet must be refrigerated after heat treatment to delay age hardening before it is driven?

Answer: 2024-T4 (DD)

2024 'icebox' rivets age-harden at room temperature and must be kept cold to stay soft enough to drive.

What is the minimum edge distance for a single row of universal-head aluminum rivets?

Answer: 2 times the rivet diameter

Minimum edge distance is 2D measured from the rivet center to the sheet edge; minimum pitch is 3D.

Exfoliation corrosion in extruded high-strength aluminum alloys is an advanced form of:

Answer: Intergranular corrosion

Exfoliation is intergranular corrosion that lifts the elongated grains of extrusions into flaky layers.