A helicopter pilot loads three cargo nets, each weighing 25 kg, without performing mass and balance calculations. After take-off, the pilot notices the helicopter is nose-heavy and lands again. The pilot determines that the CG must be moved 5 cm aft to be within the forward CG limit. The pilot can move only two out of the three cargo nets aft by 1.0 m each. The Take-off mass is 1017 kg. If the two cargo nets are moved aft by 1.0 m, will it be sufficient to bring the CG within limits?
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A
Yes, because moving 50 kg by 1.0 m moves the CG more than 5 cm.
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B
Yes, because the total cargo is 75 kg and any aft shift improves CG.
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C
No, the two cargo nets would need to be moved at least 1.02 m aft to bring the CG within limits.
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D
No, it is impossible to correct CG by moving cargo nets; fuel must be burnt off.
For this question apply the following formula, solving for Distance Moved:
- Mass Change / Total Mass = Change of CG / Distance Moved
1. Mass Change: 2 x 25 kg = 50 kg, because only two cargo nets can be moved.
2. Total Mass: 1017 kg, the same as the Take-off Mass. The mass of the three cargo nets is included in the TOM.
3. Change of CG: The CG must be moved aft by 5 cm to be within CG limits.
4. Thus, the required distance moved to bring the CG within limits is:
- Distance Moved = Total Mass x Change of CG / Mass Change
- Distance Moved = 1017 kg x 5 cm / 50 kg
- Distance Moved = 101.7 cm or 1.02 m approximately
By moving the two cargo nets only 1.0 m aft is not enough, and the CG will be again forward of the forward CG limit. Thus, the two cargo nets would need to be moved at least 1.02 m aft to bring the CG within limits.
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This question has appeared on the real examination, you can find the related countries below.
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Austro Control1
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