On March 26, 2004, at 1157 mountain standard time, a taxiing Maule M-5-210C, N339X, collided with a stationary Cessna 172, N5345G, substantially damaging both airplanes at Jefferson County Airport, Broomfield, Colorado. The airline transport pilot aboard the Maule, and the commercial flight instructor and dual student aboard the Cessna were not injured. Visual meteorological conditions prevailed. No flight plan had been filed for either of the two local flights being conducted under the provisions of Title 14 CFR Part 91. Both flights were originating at the time of the accident. According to the flight instructor aboard the Cessna, they were stationary in the run-up area for runway 11L, facing an approximate heading of 240 degrees. They had just completed an engine run-up and the student was conducting an instrument scan. The flight instructor looked up momentarily to see the Maule headed straight for the nose of the Cessna. The right wing of the Maule went under the left wing of the Cessna, the propeller blade of the Maule penetrated the windscreen on the left side of the Cessna and the propellers of both airplanes struck each other. The airline transport pilot onboard the Maul stated that despite the S-turns performed during the taxi, he did not see the Cessna. The Cessna sustained a crushed cowling, wrinkled firewall and a bent left wing strut. The right leading edge of the Maule wing was crushed, the wing nose ribs bent, and the cowling crushed.