Accident Overview
On May 5, 2015, at about 1024 eastern daylight time, an experimental amateur-built Fischer RV-7, registration N364SJ, was substantially damaged during an emergency landing near Bartow, Georgia. The commercial pilot, who was the sole occupant, received minor injuries. The flight was conducted under visual meteorological conditions with no flight plan filed.
The flight departed East Georgia Regional Airport (SBO) in Swainsboro, Georgia, around 1000, destined for Gwinnett County Airport-Briscoe Field (LZU) in Lawrenceville, Georgia, as the first leg of a cross-country trip to Wyoming.
Pilot Information
The pilot held a commercial pilot certificate with ratings for airplane single-engine land, instrument airplane, and instrument helicopter. He reported 3,000 hours of total flight experience, with 300 hours in the accident airplane make and model. His most recent FAA second-class medical certificate was issued on May 4, 2014.
Aircraft Information
The airplane was a single-engine, low-wing, fixed tricycle-gear design, powered by an experimental engine rated at 180 horsepower that resembled a Lycoming O-360A1A reciprocating engine. According to maintenance records, the airplane had accumulated about 38.1 hours since its most recent condition inspection, completed on April 20, 2015. At that time, total airframe and engine time was about 364.4 hours.
Pre-Accident Events
On the morning of the accident, the pilot noted the oil level was 1.5 quarts above the minimum. An engine run-up check prior to takeoff revealed no anomalies. After departure, the pilot initiated a climb and established a direct course to LZU. About five minutes after takeoff, he leveled the airplane at 2,500 feet mean sea level and configured for cruise, but the engine would not exceed 2,100 rpm—300 rpm below desired cruise power. He attempted to adjust the mixture and activated the electric fuel pump, but engine power remained steady at about 2,100 rpm.
The pilot elected to make a precautionary landing at a nearby airport. Moments after diverting, the engine oil temperature increased quickly, and oil began to cover the windshield. He subsequently attempted a precautionary landing on a dirt road. During the landing, the left wingtip struck the ground, causing the airplane to cartwheel and come to rest inverted. The wings and rudder sustained substantial damage.
Weather Conditions
The recorded weather observation at Kaolin Field (OKZ) in Sandersville, Georgia, located about 13 nautical miles northwest of the accident site, at 1015, included winds from 060 degrees at 5 knots, clear skies, 10 miles visibility, temperature 22°C, dew point 15°C, and an altimeter setting of 30.33 inches of mercury.
Postaccident Examination
A postaccident examination by a Federal Aviation Administration inspector, assisted by an airframe and powerplant mechanic, revealed that the forward crankcase seal on the engine was intact but had separated forward of the crankcase. Approximately 10 gallons of non-ethanol 90-octane automotive gasoline was drained from the wing tanks.
Spark plugs were removed and examined. All plugs except the number 1 top plug were secured properly and appeared normal in wear. The number 1 top spark plug was removed by hand and exhibited normal operating signatures. The magnetos were not examined, and magneto timing could not be verified due to impact damage.
Further disassembly of the engine showed that portions of the number 1 cylinder wall, compression rings, and oil control ring had been burned through. The number 1 piston head also displayed thermal deterioration and pitting on the piston face. The numbers 2, 3, and 4 cylinder combustion chambers and their associated pistons exhibited normal operating signatures.
The last engine logbook entry indicated the engine was inspected in accordance with the condition inspection checklist provided by the manufacturer.
According to the Sky Ranch Engineering Manual, detonation is a process of self-ignition or explosive combustion that occurs when the unburned charge of compressed fuel reaches a critical temperature in the cylinder. According to a service letter issued by the engine manufacturer, "Use of lower-than-specified octane fuel could cause detonation and mechanical damage to the engine." The service letter did not list 90-octane rated fuel as an approved automotive fuel for use in this engine.
No probable cause was stated in the source.