FAA Private Pilot Helicopter (PRH)Performance and LimitationsHard
During preflight loading, a pilot places all cargo and a heavy passenger on the right side of the cabin, with no compensating weight on the left. During the subsequent hover check, the pilot must apply continuous left cyclic to keep the helicopter level. What does this indicate?
- AThe tail rotor is producing excessive thrust for the load configuration
- BThe helicopter's longitudinal CG is too far forward
- CThe main rotor RPM is set too low for the current loading
- DThe helicopter's lateral CG is displaced to the right, near or beyond the lateral limit
Show answer & explanationAnswer & explanation
Correct answer: D. The helicopter's lateral CG is displaced to the right, near or beyond the lateral limit
Uneven side-to-side loading shifts the lateral center of gravity toward the heavy side. Needing continuous cyclic displacement (here, left cyclic to counter a right-side-heavy load) to maintain a level hover indicates the lateral CG is approaching or beyond its limit, reducing control margin.
Why the other options are wrong
- A. Tail rotor thrust relates to yaw/anti-torque, not lateral CG compensation via cyclic.
- B. Longitudinal CG issues involve fore-aft loading and require fore-aft cyclic, not lateral.
- C. Rotor RPM is governed independently and is not related to lateral loading imbalance.
Lateral CG Limits
Uneven side-to-side loading shifts the lateral center of gravity, requiring cyclic displacement to compensate; if the CG exceeds lateral limits, the helicopter may not be controllable in all flight regimes.
- Caused by unequal loading side-to-side (e.g., single pilot seat, side cargo)
- Detected by needing sustained lateral cyclic input to hover level
- Exceeding limits can leave insufficient cyclic control margin for maneuvering
Memory trick: Heavy side pulls, cyclic must push back — but only so far.