FAA Aviation Mechanic Airframe (AMA)Airframe StructuresEasy
A technician examining a semi-monocoque fuselage section identifies a heavy longitudinal structural member that runs the full length of the fuselage, attaches to the bulkheads, and has a much larger cross-sectional area than the surrounding stiffeners. What is this member called?
- ARib
- BBulkhead
- CLongeron
- DStringer
Show answer & explanationAnswer & explanation
Correct answer: C. Longeron
Longerons are the heaviest longitudinal members in a semi-monocoque fuselage, spanning greater distances between bulkheads and providing the primary resistance to bending loads. Stringers are smaller, more numerous, and mainly stabilize the skin.
Why the other options are wrong
- A. Ribs are found in wings/control surfaces, not fuselage longitudinal framing.
- B. Bulkheads are transverse (circumferential) members, not longitudinal.
- D. Stringers are lighter, closely spaced longitudinal stiffeners, not the heaviest member.
Longeron
A heavy longitudinal structural member running the length of a semi-monocoque fuselage, attached to bulkheads, that resists bending loads.
- Larger cross-section than stringers
- Spans between bulkheads
- Works with skin and frames to carry bending loads
Memory trick: Longeron = LONG and strong, the backbone beam.