On April 20, 2010, about 1900 mountain daylight time, a Piper PA-44-180, N331GP, experienced a gear collapse during a forced landing about two miles southeast of Tooele Valley Airport, Tooele, Utah. The certified flight instructor was not injured, but his private pilot-rated student received minor injuries. The airplane, which was operated by Leading Edge Aviation, sustained substantial damage to both its fuselage and wings. The 14 Code of Federal Regulation Pat 91 instructional flight departed Salt Lake City International Airport about 60 minutes prior to the accident. The flight was being operated in visual meteorological conditions. No flight plan had been filed. According to the flight instructor, after departing the Salt Lake City area the student executed a simulated engine-out instrument landing system (ILS) approach to Tooele Valley Airport. During that approach the right engine was set at idle. At the completion of that approach, a touch-and-go landing was performed with both engines being brought up to full power during the takeoff. The student then stayed in the VFR (visual flight rules) pattern, and performed a short field landing using both engines, followed by a normal takeoff using both engines. During the initial climb, as the airplane reached a height of about 200 to 300 feet above ground level (agl), it suddenly lost all power in the left engine. At that time the flight instructor took control of the airplane, confirmed that the left engine had lost all power, checked the position of the fuel selector valves, and then attempted to feather the left engine. The left engine did not fully feather due to insufficient oil pressure as a result of the low engine rpm, and soon thereafter the instructor pilot turned to the left in an attempt to get back around to the airport. After he initiated the turn to the left (into the power-out engine) the airplane started to descend, and it became obvious to the instructor that the airplane was losing altitude too quickly for him to safely maneuver back around to the airport. He therefore picked out an area for a forced landing and headed toward that location. While he was about 50 feet in the air he lowered the landing gear, but he left the flaps in the full up position. Although the touchdown was successful, during the landing roll the airplane encountered rough terrain that resulted in the collapse of the left main landing gear. Two days after the accident, the private pilot, who was receiving instruction in preparation for a multi-engine rating proficiency check, revealed that after performing the engine cross-feed check prior to departing Salt Lake International Airport, she had inadvertently forgotten to correctly reposition the right fuel selector to the "ON" position. The result of that omission created a situation where both engines were feeding off of the left fuel tank (right engine in cross-feed). She further stated that when the left engine lost power during the initial climb, she noticed the incorrect fuel selector position, and reset it to the "ON" position so that the right engine was feeding off of the right fuel tank. She further stated that she did not mention the repositioning of the fuel selector valve to the flight instructor during the accident sequence, and therefore when he checked the position of the fuel selectors after taking control of the airplane, he had no idea that the selector had been incorrectly positioned and then repositioned. In a phone conversation with the NTSB Investigator-In-Charge, the flight instructor said he had not noticed the incorrectly positioned fuel selector, and neither he nor the private pilot noticed the unequal fuel tank quantity that developed as the flight progressed. The investigation also revealed that the private pilot was using an expanded checklist produced by CheckMate Aviation Inc., instead of the expanded checklist produced by Leading Edge Aviation (the operator). A review of those two checklists revealed that both were expanded to include items/steps beyond those found in the Pilot's Operating Handbook (POH) provided by the airplane's manufacturer. Both checklists called for the cross-feed check to be completed prior to the initiation of the Before-Takeoff portion of the checklist, but only the Leading Edge Aviation version included an extra step in the Before-Takeoff section that called for the pilot to recheck that the fuel selector valves had been reset in the "ON" position (as opposed to still in cross-feed). A further discussion with Leading Edge Aviation personnel revealed that although it was expected that instructor pilots, students, and renters would use the Leading Edge Aviation checklist, there was no written policy that required them to do so.