On November 17, 2014, at 1720 central daylight time, a Cessna 401A, multi-engine airplane, N401ME, was substantially damaged after impacting terrain following a loss of engine power during takeoff at Elton Hensley Memorial Airport (FTT), Fulton, Missouri. The two pilots and the passenger all sustained serious injuries. The airplane was registered to and operated by Heartland Air, LLC; Mablelvale, Arkansas. Evening dusk visual meteorological conditions (VMC) prevailed at the time of the accident and an instrument flight rules (IFR) flight plan had been filed for the 14 Code of Federal Regulations Part 91 business flight. The intended destination was Memorial Field Airport (HOT), Hot Springs, Arkansas. The pilot reported that immediately after takeoff the right engine suddenly lost power and he aborted the takeoff. When the pilot saw he would not be able to stop on the runway he shut down the opposite engine. The airplane exited the end of the runway surface, impacted rough terrain, and came to rest upright. Fuel tanks were impact breached which resulted in a significant fuel spill, however there was no postimpact fire. Several witnesses called 9-1-1 emergency and ran to the wreckage location to provide aid to the three injured persons. An on-scene examination of the wreckage revealed no evidence of preimpact mechanical malfunctions or failures that would have precluded normal operation. Both engines were removed and examined at the facilities of Continental Motors, Inc. in Mobile, Alabama. The left engine was installed in an engine test cell, and it performed normally throughout the test cell procedure. The right engine was installed in a test cell and several attempts to start the engine were unsuccessful. Examination showed that the magneto distributor drive gears were not turning. Both magnetos were removed and replaced with a slave set of magnetos. The right engine then started and preformed normally throughout the test cell procedure. The original magnetos from the right engine were then disassembled and both nylon magneto distributor gears had missing gear teeth and were observed to have discolored to a brown color. They were compared to a new nylon magneto distributor gear, which was white. A review of aircraft maintenance records for the right engine showed that the At the time of the accident, the right engine had been operated for about 8-years and an estimated 697 hours since the most recent magneto overhauls had been completed. At 1653 the automated weather observing system at Columbia Regional Airport (COU), Columbia, Missouri, located about 10 miles west from the accident location, reported wind from 290° at 19 knots gusting to 24 knots, visibility of 10 miles, scattered clouds at 5,000 feet, temperature minus 7° C, dew point minus 17° C, with an altimeter setting of 30.20 inches of Mercury. Data from the U.S. Naval Observatory showed that sundown occurred at 1653 and the end of evening civil twilight occurred at 1721. ADDITIONAL INFORMATION According to the Continental Service Bulletin SB643B (April 6, 2005) Paragraph 3. A. "Magnetos … must be inspected every 500 hours …" Paragraph 4. C. "Magnetos must be overhauled or replaced at the expiration of five years since … the last overhaul … without regard to accumulated operating hours" According to the Continental S-20/S-200 Series High Tension Magneto Service Support Manual (August 31, 2011) Page 7-3. When servicing the magneto " … If the color of the gear has turned brown or the gear teeth are turning brown, the gear has been exposed to extreme heat, discard and replace the gear".