Metro III F-GILN was chartered to repatriate survivors from a serious bus accident to the U.K. The crew estimated that the aircraft was loaded at its maximum takeoff weight of 14500 lb. Actually, the airplane was 658 lb over its mtow. V1 and VR were calculated being 107 kts. The aircraft taxied to runway 18 for departure and the throttles were advanced. While accelerating through a speed of 100 kts, 1100 m down the runway, the copilot noted that the no. 2 engine power decreased from 93% to 40%. The captain then decided to abort the takeoff. The aircraft does not appear to slow down as expected, so the captain requested the no. 2 and after that the no. 1 engines to be stopped. The airplane could not be brought to a halt on the runway. At the end of the runway the Metro became airborne for one metre due to the raised lip of the runway. It skidded for 150 metres over loose ground and came to rest against a localizer antenna. The undercarriage had collapsed during the skid. PROBABLE CAUSE (translated from French): The accident appears to be due to a combination of a positioning error of the Speed Levers at the time of take-off, leading to the overheating of both engines, which forced the take-off to stop, and to the preparation and insufficient management of the take-off, leading to an underestimation of the acceleration-stop distance and a late decision to reject the take-off. Contributors to this accident: – the fouling of the brakes, which reduced their performance, – the failure to update the aircraft’s base weight in the operations manual, – the crew’s very limited experience on SA227.