Chapter 2 Section D (Unit 2)

2-82 AMA016

Shallow scratches in sheet metal may be repaired by

A- buffing.

B- burnishing.

C- stop drilling.

2-82. Answer B. JSAT 2D

Scratches in aluminum alloy skins encourage corrosion to form, and concentrate the stresses enough that they may cause the part to crack. If the scratch is not too deep, it can be burnished with a smooth, round-end piece of steel to force the metal back into the scratch.

2-83 AMA016

Which statement is true regarding the inspection of a stressed skin metal wing assembly known to have been critically loaded?

A- If rivets show no visible distortion, further investigation is unnecessary.

B- If genuine rivet tipping has occurred, groups of consecutive rivet heads will be tipped in the same direction.

C- If bearing failure has occurred, the rivet shanks will be joggled.

2-83. Answer B. JSAT 2D, FAH

The presence of chipped or cracked paint around the heads of rivets may indicate shifted or loose rivets. If tipped or loose rivet heads are noticed, they will generally show up in groups of several consecutive rivets, and will probably be tipped in the same direction.

2-84 AMA016

Repairs or splices involving stringers on the lower surface of stressed skin metal wings are usually

A- permitted only if the damage does not exceed 6 inches in any direction.

B- not permitted.

C- permitted but are normally more critical in reference to strength in tension than similar repairs to the upper surface.

2-84. Answer C. JSAT 2D, AC 43.13-1B

Repairs or splices involving stringers are allowed, but it is especially important that care be taken when splicing stringers on the lower surface of stressed skin wings. It is in this area of the wing that very high-tension stresses exist.

2-85 AMA016

What is indicated by a black “smoky” residue streaming back from some of the rivets on an aircraft?

A- Fretting corrosion is occurring between the rivets and the skin.

B- Exfoliation corrosion is occurring inside the structure.

C- The rivets were excessively work hardened during installation.

2-85. Answer A. JSGT 12A

Fretting corrosion may occur around rivets in a skin, and will be indicated by dark deposits around the rivet heads streaming out behind, give the appearance of “rivet smoking.”