On July 17, about 1515 Pacific daylight time, a Piper PA-30 twin-engine airplane, N7981Y, was substantially damaged following a partial loss of power on the left engine, and a collision with terrain during takeoff/initial climb at the Othello Municipal Airport, Othello, Washington. The private pilot and the three passengers were not injured. The airplane was registered to Warden Air, LLC and operated by the pilot as a Title 14 Code of Federal Regulations Part 91 personal flight. An instrument flight rules (IFR) flight plan was filed for the cross-country flight. The airplane was departing at the time and was destined for Klamath Falls, Oregon. The pilot reported that during the power up for takeoff, the left engine revolutions per minute (RPM) was 2,200 while the right engine was 2,600 RPM. He leaned the mixture on the left engine to bring the RPM up to 2,600 and proceeded with the takeoff. After the takeoff roll he initiated a climb and noted that the exhaust gas temperature (EGT) on the left engine was much higher than the EGT of the right engine. The left engine RPM suddenly dropped to 2,000 RPM and the airplane yawed to the left and started to descend. The pilot was unable to overcome the yaw and descent, and the airplane impacted the ground. The pilot reported that he should not have leaned the left engine for takeoff. A review of the left engine's logbook revealed a logbook entry dated March 21, 2014 indicating that the fuel flow divider had been removed, repaired, and reinstalled. The fuel servo and turbo charger had also been removed, repaired, and reinstalled. The entry also noted that a flow test was performed, the engine was run tested and checked for leaks, and returned to service. The pilot did not provide the time the airplane had flown since the maintenance work was completed. The NTSB did not respond to the accident site and the wreckage was retained by the insurance company. Prior to examination, the wreckage and engines were sold for salvage and no longer available for examination.