NTSB Factual Report

HISTORY OF FLIGHT

On December 3, 2011, at 2151, eastern standard time, a Cirrus Design Corp. SR20, N486DA, registered to Boston Aviation Leasing II LLC and 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 on an instrument flight rule (IFR) flight plan for the Title 14 Code of Federal Regulations Part 91, instructional flight. The flight last departed from Orlando Sanford International Airport (SFB), Sanford, Florida, about 2030.

In a written statement, the instructor said that he and his student were on an IFR cross-country flight. They departed the Jacksonville Executive Airport at Craig (CRG), Jacksonville, Florida around 1500, and made 2 stops.

On the last leg of the flight while descending from 3,000 feet to 2,000 feet, approximately 12.3 nautical miles from CRG, the engine "coughed". This event did not seem abnormal to the flight crew but seconds later the engine "coughed" again followed by a "bang", engine vibration, and a decrease in engine revolutions per minute (RPM) to 1,800. The instructor advised Jacksonville approach control that the airplane had experienced a partial loss of engine power and the controller provided distances to CRG and Naval Air Station Jacksonville (NIP). The instructor advised Jacksonville approach that the airplane could not reach either airport and he elected to perform a forced landing to an interstate highway. During the descent, the airplane experienced a total loss of engine power, and the instructor maneuvered the airplane under and around bridges and signs to complete the landing.

PERSONNEL INFORMATION

The 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 Federal Aviation Administration (FAA) second class medical certificate was issued on May 1, 2008. FAA data indicted the instructor had acquired 829 total flight hours as of December 3, 2011. The instructor's last regulatory check ride prior to this incident occurred on August 23, 2011. The instructor provided a written statement but an NTSB Form 6120.1 Pilot/Operator Aircraft Accident/Incident Report was not generated for this event.

AIRPLANE INFORMATION

The accident airplane was manufactured in 2007 and was equipped with a Continental Motors IO-360-ES reciprocating engine which was rated to produce 210 horsepower. The airplane's most recent 100 hour inspection was completed on October 27, 2011. At that time the airframe had accumulated 3788.5 hours since new. The factory rebuilt engine was installed on the airframe on July 22, 2009 when total accumulated airframe time was 2177 hours. Since that time the engine had accumulated 1652 hours.

METEOROLOGICAL INFORMATION

The weather conditions reported at CRG at 2153 located 10 nautical miles south of the off airport landing included wind from 030 degrees at 6 knots, visibility 9 statute miles with clear skies. The temperature was 17 degrees C, dew point 15 degrees C, and the altimeter setting was 30.37 inches of mercury.

WRECKAGE INFORMATION

The airplane was not damaged during the off airport landing. Despite several attempts following the accident, the operator was unable to restart the airplane's engine.

The engine was subsequently removed from the airplane and returned to the manufacturer for evaluation. It was shipped as removed with no disassembly other than required for removal. The manufacturer conducted an engine teardown overseen by an NTSB investigator.

An engine examination was completed by the manufacturer who provided a detailed report. The manufacturers report summarized that the engine revealed the crankshaft gear was mechanically damaged and that missing gear teeth and damaged teeth were contained in the engine oil sump. The camshaft gear was damaged and the teeth were worn away. The crankshaft gear with bolts, camshaft gear with bolts, oil pump drive gear and driveshaft, and oil sump debris were sent to the NTSB materials laboratory in Washington DC for further inspection and analysis.

The NTSB materials laboratory staff examined the crankshaft gears with bolts, the camshaft gear with bolts, the oil pump drive gear and driveshaft and the oil sump debris and concluded that the engine failure was a result of fatigue failure of a tooth on the crankshaft gear that led to failure of multiple teeth on the camshaft timing gear and subsequent loss of correct valve timing in the engine. No obvious defects were visually apparent on the failed gear. The fracture appeared typical of tooth bending from normal gear tooth meshing. Damage to the oil pump drive gear was secondary as a result of ingestion of gear teeth pieces from the crank and cam gears. Metallurgical properties of the crankshaft gear were not evaluated.

The engine, s/n1000738 IO360ES, was installed in the airframe as a rebuilt engine on July 22, 2009. Total time on the airframe at the time of this engine installation was 2177.7 hours. Total time on the airframe at the time of the incident on December 3, 2011 was 3830 hours. Total engine time at time of failure was 1652.3 hours.

According to the manufacturer the crankshaft gear would be inspected during an engine overhaul that normally occurs at the 2000 hour time between overhaul (TBO), and longer under certain circumstances on the IO360ES engine. The manufacturer was familiar with gear tooth failures on other models of Continental engines but not with this type of tooth failure on the IO360ES.

NTSB Probable Cause

The failure of a crankshaft gear tooth due to fatigue, which resulted in the loss of several additional gear teeth and a subsequent total loss of engine power.