History of Flight
On December 3, 2011, at 2151 eastern standard time, a Cirrus Design Corp. SR20, registration N486DA, operated by Aerosim Flight Academy, conducted a forced landing to an interstate highway near Jacksonville, Florida, following a total loss of engine power. The airplane was undamaged and the flight instructor and student were not injured. Night visual meteorological conditions prevailed and the flight was conducted under an instrument flight rules (IFR) flight plan for a Part 91 instructional flight. The flight departed from Orlando Sanford International Airport (SFB) about 2030.
According to the instructor's written statement, he and his student were on an IFR cross-country flight. They had departed Jacksonville Executive Airport at Craig (CRG) around 1500 and made two stops. On the last leg, while descending from 3,000 feet to 2,000 feet approximately 12.3 nautical miles from CRG, the engine "coughed." This did not seem abnormal, but seconds later the engine coughed again followed by a "bang," engine vibration, and a decrease in RPM to 1,800. The instructor advised Jacksonville Approach that the airplane had experienced a partial loss of engine power. The controller provided distances to CRG and Naval Air Station Jacksonville (NIP). The instructor determined the airplane could not reach either airport and elected to perform a forced landing to an interstate highway. During the descent, the engine experienced a total loss of power, and the instructor maneuvered under and around bridges and signs to complete the landing.
Personnel Information
The flight instructor held a commercial pilot certificate with ratings for airplane single-engine land, airplane multiengine land, and instrument airplane, as well as a flight instructor certificate with ratings for airplane single-engine, multi-engine, and instrument airplane. His most recent FAA second-class medical certificate was issued on May 1, 2008. He had accumulated 829 total flight hours as of December 3, 2011. His last regulatory check ride before the incident occurred on August 23, 2011.
Aircraft Information
The accident airplane was manufactured in 2007 and equipped with a Continental Motors IO-360-ES reciprocating engine rated at 210 horsepower. The most recent 100-hour inspection was completed on October 27, 2011, at which time the airframe had accumulated 3,788.5 hours since new. A factory rebuilt engine was installed on July 22, 2009, when total airframe time was 2,177 hours. Since then, the engine had accumulated 1,652 hours.
Meteorological Information
Weather reported at CRG at 2153, located 10 nautical miles south of the landing site, included wind from 030 degrees at 6 knots, visibility 9 statute miles, clear skies, temperature 17°C, dew point 15°C, and altimeter setting 30.37 inches of mercury.
Wreckage and Impact Information
The airplane was not damaged during the off-airport landing. Despite several attempts, the operator could not restart the engine after the incident.
The engine was removed and sent to the manufacturer for evaluation. An engine teardown was conducted under oversight by an NTSB investigator. The manufacturer's report summarized that the crankshaft gear was mechanically damaged, with missing and damaged teeth in the oil sump. The camshaft gear was damaged and its teeth worn away. Components were sent to the NTSB materials laboratory for analysis.
The NTSB materials laboratory concluded that the engine failure resulted from fatigue failure of a tooth on the crankshaft gear, leading to failure of multiple teeth on the camshaft timing gear and subsequent loss of correct valve timing. No obvious defects were visually apparent on the failed gear, and the fracture appeared typical of tooth bending from normal meshing. Damage to the oil pump drive gear was secondary from ingesting gear tooth pieces. Metallurgical properties of the crankshaft gear were not evaluated.
The engine (serial number 1000738) was installed as a rebuilt engine on July 22, 2009, when total airframe time was 2,177.7 hours. At the time of the incident on December 3, 2011, total airframe time was 3,830 hours, and total engine time was 1,652.3 hours. According to the manufacturer, the crankshaft gear would be inspected during an engine overhaul, normally at 2,000 hours time between overhaul (TBO). The manufacturer was familiar with gear tooth failures on other Continental engine models but not with this type of failure on the IO-360-ES.