NTSB Factual Report

On May 18, 2018, about 2032 central daylight time, an experimental amateur-built Vans RV7A single-engine airplane, N667AZ, was substantially damaged during a forced landing following a partial loss of engine power near Hanover Park, Illinois. The airline transport pilot sustained minor injuries. The airplane was registered to and operated by the pilot under the provisions of Title 14 Code of Federal Regulations (CFR) Part 91 as a personal flight. Day visual meteorological conditions prevailed for the personal cross-country flight that departed Schaumburg Regional Airport (06C) about 2029 with the intended destination of Terre Haute Regional Airport (HUF), Terre Haute, Indiana.

The pilot reported that he completed a normal preflight inspection that revealed no anomalies with the airplane or its engine. He stated that there was no water contamination in the fuel samples that he obtained from each wing tank. He noted that there were only two fuel sumps, one located under each wing. The airplane was not equipped with a drainable fuel filter assembly. The pilot reported that the engine started without hesitation and that there were no anomalies during his before-takeoff engine runup. The pilot made a normal takeoff from runway 11 before entering a left downwind departure from the traffic pattern. He noticed an elevated number 1 engine cylinder exhaust gas temperature as the airplane was climbing through 1,600 ft mean sea level (msl) and the engine began to run rough. The pilot stated that he selected the fuel boost pump to ON, switched fuel tanks, and ensured that the throttle, mixture, and propeller controls were full forward. The engine operation did not improve despite the pilot's corrective actions and the airplane was unable to maintain altitude. The pilot initially began a turn back toward the airport, but ultimately decided to maneuver toward a nearby vacant field to remain clear of a densely populated area. The pilot stated that the airplane nosed over upon touchdown in the soft field. He was able to exit the airplane unaided with minor injuries.

A postaccident examination of the airplane and its engine was completed by a National Transportation Safety Board (NTSB) investigator and a Federal Aviation Administration (FAA) airworthiness inspector. The engine remained attached to the firewall. The propeller remained attached to the propeller flange. One propeller blade exhibited a slight aft bend, was twisted toward low-pitch, and had a leading-edge gouge near the blade tip. The other propeller blade exhibited a slight aft bend. The propeller flange was bent aft slightly, which resulted in the ring gear binding with the starter Bendix drive during crankshaft rotation. The propeller and ring gear were removed to facilitate full crankshaft rotation. Internal engine and valve train continuity were confirmed as the engine crankshaft was rotated by hand. Compression and suction were noted on all cylinders in conjunction with crankshaft rotation. The upper spark plugs were removed and exhibited features consistent with normal engine operation. The engine was equipped with an electronic ignition system, which was not tested. Engine control cable continuity was confirmed from the cockpit controls to their respective engine component. The fluid contained in the supply line to the fuel injector servo was drained into a clear container for a visual examination. The recovered fluid contained a mixture of 100 low-lead aviation fuel and a small amount water contamination. The electric fuel pump was used to obtain an additional fuel sample, which also contained water contamination. Fuel samples taken from each wing tank sump were free of any water contamination. The fuel filter was removed from the fuselage and its contents drained for a visual analysis. Water detection paste was used to confirm that the fluid collected from the fuel filter contained water. The fuel filter was disassembled, and its filter screen tested positive for water contamination. Besides the observed fuel contamination, the postaccident examination did not reveal any anomalies that would have precluded normal engine operation during the flight.

A review of maintenance documentation revealed that on February 20, 2017, water and particulate contamination was observed in the fuel filter and the fuel injection servo finger screen during a routine condition inspection. The final airframe logbook entry, dated March 27, 2018, did not indicate if any water or particulate contamination had been observed; however, the logbook entry did note that the fuel filter and fuel injector servo finger screen had been removed and cleaned. The airplane had flown 5.6 hours since the last condition inspection.

A postaccident review of available meteorological data established that day visual meteorological conditions prevailed at the accident site. The nearest aviation weather reporting station was located at Schaumburg Regional Airport (06C) about 2 miles east-southeast of the accident site. At 2035, about 3 minutes after the accident, the 06C automated surface observing system reported: wind 090° at 7 knots, 4 miles surface visibility, an overcast ceiling at 300 ft above ground level (agl), temperature 14°C, dew point 13°C, and an altimeter setting 29.95 inches of mercury.

Federal aviation regulations classify daytime as the time between morning civil twilight and the end of evening civil twilight, with nightime commencing at the end of evening civil twilight. A query of United States Naval Observatory data established that the end of evening civil twilight occurred at 2042 on the day of the accident. As such, the accident occurred during daytime. The weather minimums required for day visual flight rules while operating in class G airspace require a pilot to remain clear of clouds and have at least 1 statute mile visibility.