CEN16LA387

The pilot was conducting a cross-country flight in an experimental airplane when he observed the fuel pressure fluctuating, and the engine began to surge. The pilot turned on the backup fuel pump but the engine continued to surge, so he diverted to a nearby airport. The pilot stated that he had difficulty visually acquiring the airport and was losing altitude while circling over the airport. He performed an "S" turn but was still too high. He was running out of runway below him, so he performed a "hard slip" to lose altitude. The airplane stalled 10-15 ft above the runway, hit the ground, and slid about 30 ft before stopping. The primary fuel pump had failed 4 days before the accident. The pilot replaced the fuel pump with a new unit that required partial assembly. He noted during assembly that there was not an O-ring where the lower fitting attached but that the mating surfaces were different between the two pumps and he had believed one was not required. The instructions with the new pump did not address the installation of an O-ring at the fitting. After the accident, the pilot reexamined the box the new fuel pump came in and found an O-ring for the lower fitting. Without the O-ring installed, the fuel system was not able to maintain the fuel pressure necessary to ensure smooth engine operation and resulted in the partial loss of engine power. The pilot stated the accident resulted from this maintenance issue.

On September 22, 2016, about 1400 central daylight time (CDT), a Vans RV9A experimental airplane, N699RV, was substantially damaged during a forced landing near Cushing Field Ltd Airport (0C8), Newark, Illinois. The private pilot was not injured and the passenger suffered minor injuries. The airplane was privately registered and operated under the provisions of Title 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed for the flight, and no flight plan was filed. The pilot and passenger were conducting a cross-country flight when the pilot observed the fuel pressure fluctuating, and the engine began sto surge. The pilot turned on the backup fuel pump; the engine continued to surge so he diverted to 0C8. The pilot stated he had difficulty maintaining visual reference to the airport and the airplane was losing altitude as he circled over the airport. The pilot performed an "S" turn and found he was still too high. He was running out of runway below him, so he performed a "hard slip" to lose altitude. The airplane stalled 10-15 ft above the runway, hit the ground, and slid about 30 ft before stopping. The pilot reported he conducted a flight four days before the accident, on September 18, and he felt a "couple small pauses in the powerplant." The engine quit after landing and did not restart until the auxiliary fuel pump was turned on. He subsequently tested the primary fuel pump, which did not work, and ordered a new fuel pump. When the new pump arrived it did not have the bottom fitting attached, whereas the previous replacement was fully assembled. The pilot took the fitting off the old pump and there was an O-ring present; however, he did not see an O-ring with the new pump "kit." He said the mating surfaces were different between the two pumps and the new pump did not appear to require an O-ring. Additionally, the instructions that came with the new pump did not mention an O-ring. The pilot installed the new fuel pump without an O-ring and conducted a successful test of the new pump. Following the accident flight, the pilot questioned whether there could have been an O-ring accompanying the new fuel pump that he had not seen. He examined the area where he performed the maintenance and subsequently located a 5/8" O-ring inside another component that came from the box containing the new pump. The pilot stated the accident was caused by this maintenance issue.