What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
On October 8, 2017 at approximately 1100 am the N85308 a Aeronca champ (7AC) departed Sawyer County Airport (khr) Hayward, WI. For a short local flight. After being airborne for approximately 20-30 minutes the aircraft began running rough with some back firing. The altitude was approximately 1200-1500 feet AGL and the pilot turned the aircraft back towards khyr. The pilot checked the mags and turned on carburetor ice. This had no noticeable improvement.
During this time the RPM was slowly dropping from the previous 2300 RPM and the aircraft was over highway 27 roughly 5 miles north of khyr. The aircrafts altitude by now was 800 AGL and RPM was 1500-1600 RPM. The pilot elected to land on the clear highway with the remaining power. There were no issues on the landing and the pilot cleared the road at a driveway.
After securing the aircraft a fuel sample was taken by the fuel filter and tank with no water present. Four to five gallons of fuel remained in the tank. The pilot restarted the aircraft and it ran good at low RPM but at higher RPM it began to backfire. A mechanic arrived on scene and removed the screen from the fuel inlet to the carburetor. A small amount of debris was detected, then the fuel line was flushed. Filter reinstalled.
The pilot started the aircraft, did mag checks and various RPM there was no backfiring or engine roughness. Engine runs at full power were completed for several minutes. It was determined to fly the aircraft from highway 27 to khyr. Flight landed without any further incident.
Records review of the pilot and aircraft found no issues.
As the FAA filed it
ON OCTOBER 8, 2017 AT APPROXIMATELY 1100 AM THE N85308 A AERONCA CHAMP (7AC) DEPARTED SAWYER COUNTY AIRPORT (KHR) HAYWARD, WI. FOR A SHORT LOCAL FLIGHT. AFTER BEING AIRBORNE FOR APPROXIMATELY 20-30 MINUTES THE AIRCRAFT BEGAN RUNNING ROUGH WITH SOME BACK FIRING. THE ALTITUDE WAS APPROXIMATELY 1200-1500 FEET AGL AND THE PILOT TURNED THE AIRCRAFT BACK TOWARDS KHYR. THE PILOT CHECKED THE MAGS AND TURNED ON CARBURETOR ICE. THIS HAD NO NOTICEABLE IMPROVEMENT.
DURING THIS TIME THE RPM WAS SLOWLY DROPPING FROM THE PREVIOUS 2300 RPM AND THE AIRCRAFT WAS OVER HIGHWAY 27 ROUGHLY 5 MILES NORTH OF KHYR. THE AIRCRAFTS ALTITUDE BY NOW WAS 800 AGL AND RPM WAS 1500-1600 RPM. THE PILOT ELECTED TO LAND ON THE CLEAR HIGHWAY WITH THE REMAINING POWER. THERE WERE NO ISSUES ON THE LANDING AND THE PILOT CLEARED THE ROAD AT A DRIVEWAY.
AFTER SECURING THE AIRCRAFT A FUEL SAMPLE WAS TAKEN BY THE FUEL FILTER AND TANK WITH NO WATER PRESENT. FOUR TO FIVE GALLONS OF FUEL REMAINED IN THE TANK. THE PILOT RESTARTED THE AIRCRAFT AND IT RAN GOOD AT LOW RPM BUT AT HIGHER RPM IT BEGAN TO BACKFIRE. A MECHANIC ARRIVED ON SCENE AND REMOVED THE SCREEN FROM THE FUEL INLET TO THE CARBURETOR. A SMALL AMOUNT OF DEBRIS WAS DETECTED, THEN THE FUEL LINE WAS FLUSHED. FILTER REINSTALLED.
THE PILOT STARTED THE AIRCRAFT, DID MAG CHECKS AND VARIOUS RPM THERE WAS NO BACKFIRING OR ENGINE ROUGHNESS. ENGINE RUNS AT FULL POWER WERE COMPLETED FOR SEVERAL MINUTES. IT WAS DETERMINED TO FLY THE AIRCRAFT FROM HIGHWAY 27 TO KHYR. FLIGHT LANDED WITHOUT ANY FURTHER INCIDENT.
RECORDS REVIEW OF THE PILOT AND AIRCRAFT FOUND NO ISSUES.