By David Mitchell
The Advocate
Sean Simmonds stood in front of an airplane on the tarmac at Louisiana Regional Airport near Gonzales and turned its large propeller by hand several times, moments after the engine had just been shut off.
Like wiping the Cessna 208B's brow past the finish line of a long, focused run over rugged terrain, Simmonds said he was cooling the engine down at the day's end.
Simmonds, a flight mechanic, and the rest of his crew with a U.S. Geological Survey contractor had spent much of a recent Friday flying the Cessna and towing a special, bomb-shaped sensor over the Baton Rouge, New Orleans and Lafayette areas to "see" deep into the ground.