Aircraft Structural Inspection Techniques Flashcards

Dark stains and soft spongy areas on a spruce wood spar generally indicate:

Answer: Moisture damage and decay

Dark discoloration and softness are signs of rot, so the member must be closely examined and likely replaced.

Per AC 43.13-1B, fabric covering is considered unairworthy when its strength falls below what fraction of the minimum required for new fabric?

Answer: 70 percent

Fabric deteriorated below 70 percent of the new minimum strength must be replaced.

Which method is best for locating cracks in a welded steel-tube engine mount?

Answer: Magnetic particle inspection

Steel is ferromagnetic, so magnetic particle readily reveals surface cracks at welds.

Stress corrosion cracking requires which combination of conditions?

Answer: Sustained tensile stress, susceptible material, and corrosive environment

All three factors must be present for stress corrosion cracks to develop.

Exfoliation corrosion is characterized by:

Answer: Lifting or flaking of metal layers, often in extruded sections

Exfoliation follows elongated grain structure and raises layers like pages of a book.

In galvanic corrosion, which metal corrodes?

Answer: The more anodic metal

The anodic member of a dissimilar-metal couple in an electrolyte is the one that is sacrificed.

Which inspection approach is commonly used to find moisture intrusion in composite honeycomb without disassembly?

Answer: Infrared thermography

Thermography shows temperature differences caused by trapped moisture within the core.