Aircraft Structural Components Questions and Answers

Answer: A

The first two are correct and follow from the definition. The third is wrong: a fairing carries no flight, ground or pressure load whose loss would hazard the aircraft, so it is secondary structure and is treated far less stringently.

Answer: B

Correct answer: A-2, B-1, C-4, D-3

Four members of the fuselage shell. Stringers run lengthwise carrying axial load and stabilising the skin between frames. Frames run around the section, maintaining its shape and introducing concentrated loads such as those from the wing and undercarriage attachments. The skin carries shear and a share of the direct stress. And the pressure bulkhead closes the pressurised volume at each end.

Answer: C

Reading the wing as a beam makes the division clear: caps are the flanges, webs the shear carriers, skins the closing walls that make torsion cheap, and ribs the chordwise members that feed the air load in and hold everything stable.

Answer: D

The three fatigue philosophies form a historical progression, each responding to the shortcomings of the last, and modern transport certification rests on damage tolerance with safe-life retained only where redundancy cannot be provided.

Answer: A

Each is a small piece of hardware answering a specific failure mode, and each has an accident history behind it. Details of this kind, rather than the sizing of the main members, are where most in-service structural trouble originates.

Answer: B

Tracing each load from where it is applied to where it is finally reacted is the essential habit of airframe layout. Wherever a large concentrated load enters a thin shell, a heavy frame or fitting appears to spread it.

Answer: C

Correct answer: Carrying the spanwise bending moment

The bending moment runs along the span and is carried by the spars and skin; the rib lies across it. What the rib does is hold the section, shorten the skin panels against buckling, and collect the air load from the skin and pass it into the spars - the three functions the other options describe.

Answer: D

Correct answer: Components are retired at a fixed life

Retirement at a fixed life is the *safe-life* philosophy, which assumes damage cannot be found reliably and so removes the part before cracking is expected. Fail-safe takes the opposite view: it assumes damage will occur and provides alternative load paths, crack stoppers and tear straps so the structure survives until inspection finds it.

Answer: A

The ratio is the other way round: the hoop stress is the larger, at twice the longitudinal value. That is exactly why cracks propagate lengthwise, driven by the hoop stress acting across them, which the remaining options describe correctly.

Answer: B

Correct answer: Increasing the spacing between stringers

Buckling stress rises as the panel gets shorter, narrower or thicker, so reducing the rib pitch, reducing the stringer spacing and thickening the skin all help. Increasing the stringer spacing makes the panel wider and therefore weaker - and since buckling stress varies roughly with the square of the thickness-to-width ratio, widening it is costly.