On September 19, 2015, about 1015 eastern daylight time, a Piper PA-28-161, N9887K, was substantially damaged by fire during an attempted engine start at Pittsburgh Northeast Airport (9G1), Pittsburgh, Pennsylvania. The private pilot was not injured. Visual meteorological conditions prevailed and no flight plan was filed for the personal flight, which was destined for Richmond International Airport (RIC), Richmond, Virginia. The airplane was owned by Tanstaafl Machine Tool Service, Inc. and operated by a private individual under the provisions of Title 14 Code of Federal Regulations Part 91.According to the pilot, the flight originated from the Butler County Airport (BTP), Butler, Pennsylvania earlier that day. During the flight he heard a "fluttering or abnormal noise" and elected to divert to 9G1. After parking the airplane on the ramp, he noticed his noise-canceling headset was not turned to the "ON" position. He subsequently performed a walk-around of the airplane and another preflight inspection. A few moments later he got back into the airplane, to continue his planned flight, as his normal procedure, primed the engine with "two pumps of the primer," and began cranking the engine. Subsequently, he observed smoke emanating from the engine area and continued to crank the engine while pulling the mixture to fuel cut-off. However, he observed flames coming out from under the cowling and exited the airplane. Due to limited resources in the immediate vicinity, the airplane continued to burn until first responders arrived, about 30 minutes later. According to a Federal Aviation Administration inspector who examined the airplane after the accident, there was substantial damage as a result of fire to the wings, cockpit, and engine area. Further examination revealed extensive fire damage in the area of the carburetor. The inspector reported that the fire "appeared to have started near the carburetor." Review of airplane maintenance records revealed that an entry, dated February 12, 2014, indicated repair following an engine fire during a start attempt. The repair included replacing various parts located on the aft side of the engine, including the carburetor. The repair was completed approximately 60 flight hours prior to the accident. The pilot reported that he was also the pilot during that engine fire event. The PA-28-161 Pilot's Operating Handbook addresses procedure for engine fire during start. Section 3, Emergency Procedures, states "Engine fires during start are usually the result of overpriming. The first attempt to extinguish the fire is to try to start the engine and draw the excess fuel back into the induction system. If a fire is present before the engine has started, move the mixture control to idle cut-off, open the throttle, and crank the engine…if fire continues more than a few seconds, the fire should be extinguished by the best available external means. The fuel selector valves should be 'OFF' and the mixture at idle cut-off if an external fire extinguishing method is to be used." Section 4, Normal Procedures, addresses starting the engine when "cold" and "hot." Only the guidance provided for starting the engine when cold addresses the need for priming the engine, there was no guidance on using the primer when the engine was hot.