Mission 8 Artic work Sling load too heavy versus documentation Charts

[Pju]

Having always generator failures in the oil platform aera.
(I've done Oilfield Campaign with numerous Sling mission without such problems).

Temp -30 C. Takeoff weigth default is 8600 Kgs on the helipad (37% fuel).
(0% fuel gives 7887 Kgs).
Sling load pipes 4350 Kgs. Total: 12950 Kgs

This to heavy regarding max takeoff weight charts with Anti-Ice (-1000 Kg).
Max load should be 13000 Kgs - 1000 Kg (hover 20 meter -30C - anti-ice).
Headwing increases  10m/s +1200 kg but for safety should not be fully used,
mission wind ground speed is 6m/s.

Max load should be 13000 - 1000 - 8600 = 3400 Kg.

Is something wrong in above computation ?

Edited January 31 by Pju
fix computation

[STONE SKY]

That seems more than logical, sir!
I will change the weight according to your calculations, thanks for the feedback.
The thing is, I didn't delve that deeply into the theory..
I just wanted to make this mission difficult. Probably overdid it! 

[Pju]

Thanks. With a ~3000 Kgs sling load it will be still difficult enough IMOO regarding weather.

Edited January 31 by Pju
fix

[STONE SKY]

Accepted! I'll fix it! Thanks again for the details!