FAA Commercial Pilot Airplane (CAX)Aerodynamics and PerformanceMedium
An airplane has a maximum positive limit load factor of +3.8G. During a flight, the pilot encounters severe turbulence causing the vertical acceleration to briefly reach +4.5G. What is the immediate consequence of this event?
- AThe aircraft is likely to have sustained permanent structural deformation.
- BThe aircraft will experience an immediate structural failure.
- CThe aircraft will enter an uncontrollable dive.
- DThe aircraft's flight controls will become inoperative.
Show answer & explanationAnswer & explanation
Correct answer: A. The aircraft is likely to have sustained permanent structural deformation.
The limit load factor is the maximum load an aircraft is certified to withstand without permanent deformation. Exceeding this, even momentarily, means the ultimate load factor (1.5 times the limit load) may have been approached or exceeded, making permanent structural deformation highly probable, though not necessarily immediate catastrophic failure.
Why the other options are wrong
- B. Immediate failure occurs at or beyond the ultimate load factor, not necessarily just above the limit.
- C. Load factor exceedance does not directly cause an uncontrollable dive; it's a structural concern.
- D. Flight controls becoming inoperative is not a direct or guaranteed consequence of exceeding limit load.
Limit vs. Ultimate Load Factor
The limit load factor is the maximum load an aircraft can withstand without permanent deformation. The ultimate load factor is 1.5 times the limit load, representing the point of structural failure.
- Limit load: no permanent deformation.
- Ultimate load: structural failure.
- Operating above limit but below ultimate causes permanent damage.
- FAA requires a 1.5 safety factor (ultimate = 1.5 * limit).
Memory trick: Limit is the 'ouch' point, Ultimate is the 'snap' point.