From the photos I have seen in the linked NTSB report, the heavy equipment was tied down to pallets using chains. If you look through the documents you'll find them. So where would the straps come into the equation? Are the pallets then strapped to the fuselage of the aircraft?
Yes. There are fixed side rails along the outboard edge and pop up do hickeys (hi tech name) down the centerline. With regular pallets there are "pallet locks" that lie flush as the pallets roll over them and then are pulled up to form a 4 inch high "X" that catches the aft edge of the forward pallet and the forward edge of the pallet behind them. However with outsize objects you have a "floating" load that doesn't fit with the pallet locks. All you can do is strap and strap and strap.