>>20266141 pb
This is what is known as a "compressor stall". Unburned Jet A builds up in the combustion stage of the turbine and then lights off erratically then stopping. Over and over. Every time it's lights off is when you see the flames and smoke exiting the exhaust section of the engine. Most likely an "igniter" problem that is intermittent. Looks scary but you go through the "engine out" prodcedure, shut it down and continue on for an emergency landing. The B747 flies real good on 3 engines and will on 2. The odds of 3 simultanously engine failures is infinitesimal. To my knowlege it has never happened.