[Why can't I sling oil barrels?]

Ahh OK i wasn't sure i thought they might be oil barrels made for the helis   Well thank you all for answering my question.

[Why can't I sling oil barrels?]

Just to make sure we are talking about the 4 barrels on a plate right?

[Why can't I sling oil barrels?]

I am having a bit of trouble with the oil barrels that you can attempt to sling.  I can get them hooked to the sling but then it drops them and gives me a message that says the sling has been cut from someone in the gunner seat.  I am using an Orca and i have also tried getting a friend to ride with me to see if that helped but no success.  Can anyone shed some light on this?