The airplane was taxiing for departure on taxiway ‘N’, when a smell fuel was detected in the cabin. About the same time, the crew of a commuter flight taxiing behind, the DC-10, reported that the right engine was on fire. The crew saw the smoke from the cockpit window, the captain stopped the airplane, shut the engines down, and order an evacuation. Crash fire rescue equipment was used to put out the fire. Examination of the right engine [No.3] revealed that the fuel/oil heat exchanger (part number 158210-11) had failed as a result of fretting wear between the baffle plate and the retaining slots in the casing, causing a fuel leak. There was no damage to the engine or the airframe. According to a passenger’s description of the evacuation there was general panic in the cabin, passengers screamed and pushed to get out. Some passengers had not cleared the bottom of the escape chute, because no one was at the bottom of the chute to help people stand up and move out of the way promptly. After evacuating the airplane passengers were standing around on the tarmac and did not know were to go, because nobody was directing passengers away from the plane. Some passengers were standing near the bottom of the chute, and others were moving away in all possible directions. Probable Cause: an on ground engine fire in the No. 3 (right) engine resulting from a failed heat exchanger, and subsequent fuel leak. A factor in this accident was the cabin crew’s improper handling of the evacuation which resulted in serious injury to a passenger.