Piper PA28 accident near Bonifay, Florida, February 21, 2018

The NTSB's narrative final · quoted from the NTSB record

The owner of the airplane experienced a partial loss of engine power during takeoff following a touch-and-go landing, but was able to complete a 180° turn and land safely back on the runway. During a post-landing engine run-up, the owner was unable to duplicate the problem, so he taxied to his hangar and reported the problem to his mechanic. The mechanic, a commercial pilot, subsequently boarded the airplane, performed an engine run-up, which seemed normal, and elected to fly the airplane around the airport traffic pattern. A witness, who heard and saw the airplane on final approach, stated that the engine was making "small explosions" or "backfire"-like sounds. The airplane subsequently collided with a tree before it impacted the ground and a fence short of the 4000-foot-long runway and was consumed by a postcrash fire. Examination of the airplane revealed that the No. 4 cylinder exhaust valve was stuck in the "open" position due to excessive deposits from the combustion process. It is likely that the stuck exhaust valve resulted in the partial loss of engine power. Maintenance records revealed that the engine had not been inspected in accordance with a manufacturer service bulletin regarding stuck valves. Had the service bulletin been complied with, it is possible that the accident may have been prevented. Despite the partial loss of engine power that occurred during the previous flight, the pilot flew a traffic pattern that resulted in the airplane descending into trees about 1/4 mile before the runway threshold after the airplane experienced a partial loss of engine power during the accident flight. The pilot was diabetic, and although his blood glucose was likely not very elevated at the time he died, it was somewhat elevated on average over the preceding few weeks. Elevated blood glucose can cause blurred vision and subjective sensation of fatigue, as well as increased thirst and urination. Unless life-threatening, it does not directly impair decision-making or judgment; thus it is unlikely that the pilot's diabetes contributed to the circumstances of this accident.

The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.