Your awning can catch wind underneath it and unfurl while you are driving. The roller must be mechanically prevented from unrolling. The lever latch at the front is supposed to do the job, but is not reliable. Securing the arms will not help.

There are several devices on the market. There is at least one commercial device that is good. http://www.awningsaver.com/
Or you can make one out of a door latch or a hook and spring. Here's how I made a holder-downer for my A&E:

Drill a 1/4" hole at 3 o'clock on the outside of the aft end drum. Bend a 3/16" rod with a hook at one end to go in the hole and an eye at the other end. The rod should be long enough for you to reach the hole from the ground. #9 wire works, too. Attach a metal spring (or even a strong bungee) between the eye in the rod and the hole in the base of the arm, using a small chain or cable and an S hook. In use, the hooked end of the rod goes in the hole, the other end of the rod is permanently attached to the spring or bungee, and the spring or bungee is attached to the hole in the base of the arm by means of the cable and “S” hook.

Additionally, an O ring can be slipped over the factory raise/lower lever to provide additional friction to keep it in the "raise" position when traveling.

Picture on request.

Good info billh. Wish I'd had the awning on my SoB tied down in such a manner.

Bill please send picture so I get it right the first time..
Thanks
John Reilly
Centerville Ohio
JReilly141@aol.com