Structures and Systems: Loads, Airframe and System Safety
Airframe structures
Understand the load types (tension, compression, shear, bending, torsion) and how the airframe carries them. Know the semi-monocoque construction: skin, stringers, frames and bulkheads, and the role of the wing spar and ribs. Understand fatigue, damage tolerance, and the meaning of a safe-life versus fail-safe design. Know the purpose of structural inspection programmes and the significance of cracks and corrosion in primary structure.
Aircraft systems
Know the function and basic operation of hydraulic, pneumatic, fuel, electrical, pressurisation, ice and rain protection, and fire detection and extinguishing systems. Understand system redundancy, the meaning of an essential bus, and the logic of a warning system. Know the difference between a system failure that is annunciated and one that is latent.
Traps
- Confusing safe-life (retire before failure) with fail-safe (structure tolerates failure).
- Assuming a warning light is the only indication of a failure; latent failures exist.
- Forgetting that structural repairs need approved data and often a damage-tolerance assessment.
Rule of thumb
For structural questions, identify the load path and the failure mode: if the load path is interrupted, the structure must have an alternative (fail-safe) or be retired before crack growth (safe-life).