Every time we run the Eagle, when we return home, we do a complete wash down of the engine internals and dry it out by conducting an engine run. After that, we borescope the engine to look for any damage. After all the runs in the dirt, we've been fortunate to come away with no damage. Part of the reason is that we do a very good fod patrol. Another part of the reason is the J-79 is one tough engine and can take a great deal of abuse. We've made a total of 48 runs with 44 of them having been on dirt (Black Rock, El Mirage, Edwards AFB and Alvord Dry Lake). A great deal of the dirt you see coming out of the engine is exactly that, dirt! We roll out very gingerly to about the 1/2 mile mark and reaching about 150 mph before you go into full military power. At that point, the engine is turning 7400 rpm and is now sucking all the air it can digest. Then, roll the throttle into minimum afterburner and when you get a good light you push it into full AB. Now you're rolling along quite nicely. You are now at about the 1 mile and just keep it pointed toward that V in the mountains about 30 miles away!