Many years ago as a newbie S/O on the 727, we were taught there were two lights to watch like a hawk. The Essential Power and the Lower Aft Body Overheat. Essential was obvious. The instructor said to consider the Lower Aft Body as the "No ******" light. No matter what the Captain said, we had a max of 20 minutes to get it on the ground before the structural integrity of the plane was gone.
In the mid 90's, a Kiwi 727 departed 36R at MCO and had a blown duct on departure. They made a 180 at the MCO VOR and landed immediately. The crew reported the controls were getting sloppy on final. After landing they fouln the entire aft section melted and the cable pulleys gone; the cables were running on the pulley bolts.
RIP to the UPS crew and heads up to all. Fire remains our biggest fear inflight.