N365R

HISTORY OF FLIGHTOn August 16, 2012, about 0839 eastern daylight time, an experimental, amateur built Jabiru J230, N365R, received substantial damage during a ditching in Gull Lake, near Otter Lake, New York, following a total loss of engine power and separation of the propeller. The public use flight was operated by Patriot Technologies LLC under contract with the Department of Defense, U.S. Air Force. The airline transport pilot and one additional crew member were not injured. Visual meteorological conditions prevailed, and no flight plan was filed for the flight which departed Burlington International Airport (BTV), Burlington Vermont about 0800, destined for Griffiss International Airport (RME), Rome, New York.

According to the operator, the purpose of the flight was to provide aerial support for a U.S. Air Force training exercise. At the time of the accident, the flight was receiving VFR flight following from the New York Air Route Traffic Control Center (ARTCC).

According to the pilot, after departing BVT, he headed westbound and climbed to 6,500 feet above mean sea level. Approximately 45 minutes into the flight, the engine began to run roughly "like it was developing carburetor ice" so the pilot applied carburetor heat. The engine however, continued to run rough and began to "cough" like it was being starved for fuel, so the pilot made sure that both fuel valves were open, and turned on the electric fuel boost pump.

The pilot then assessed that the engine might stop running, so he called for the high altitude engine failure checklist. However, before he and his crewmember began the checklist, the propeller came off the engine, struck the right side of the cowling, struck the right lift strut, and fell away.

The pilot then declared an emergency with the ARTCC, began evaluating landing sites, and elected to ditch in a nearby lake. After ditching, the airplane came to rest on the surface of the lake with the cabin halfway submerged. Both crewmembers then egressed from the cabin, swam to the lake shore, and were later picked up by helicopter. The airplane later sank to the bottom of the lake. PERSONNEL INFORMATIONAccording to Federal Aviation Administration (FAA) and pilot records, the airline transport pilot, held an airline transport pilot certificate with a rating for airplane multi engine-engine land, commercial privileges for airplane single-engine land, and type ratings in the BE-300, and C-295. He also held a flight instructor certificate with ratings for airplane multi-engine, and instrument airplane. His most recent FAA second-class medical certificate was issued on June 4, 2012. He reported 3,147 hours of total flight experience, 42 of which were in the airplane make and model.

The crew member held a commercial pilot certificate with ratings for airplane multi-engine land limited to center thrust, instrument airplane, and private privileges for airplane single-engine land. At the time of the accident he did not possess a valid FAA medical Certificate. He reported 2,350 hours of total flight experience. AIRCRAFT INFORMATIONAccording to FAA and airplane maintenance records, the airplane was manufactured in 2005. The airplane's most recent conditional inspection was completed on February 27, 2012. At the time of the accident, the airplane had accrued 915.2 total hours of operation. The engine had accrued 531.2 total hours of operation. METEOROLOGICAL INFORMATIONThe recorded weather at RME, approximately 25 nautical miles southwest of the accident site, at 0853, included: calm winds, visibility 10 miles, overcast sky at 1,200 feet, temperature 19 degrees C, dew point 16 degrees C, and an altimeter setting of 29.98 inches of mercury. AIRPORT INFORMATIONAccording to FAA and airplane maintenance records, the airplane was manufactured in 2005. The airplane's most recent conditional inspection was completed on February 27, 2012. At the time of the accident, the airplane had accrued 915.2 total hours of operation. The engine had accrued 531.2 total hours of operation. WRECKAGE AND IMPACT INFORMATIONFour days after the ditching occurred, the airplane was recovered from the lake. Examination revealed that the airplane was substantially damaged due to water immersion.

Further examination revealed that the entire propeller assembly, including the propeller spinner, and propeller flange extension, had separated from the forward portion of the engine crankshaft.

Despite a search of the surrounding area, the separated components of the propeller assembly were not found. ADDITIONAL INFORMATIONIn order to improve safety the participants in this investigation took the following actions:

Patriot Technologies Group LLC

- On September 18, 2012, Patriot Technologies Group advised the NTSB that they would be installing new propeller flange hubs (Jabiru Part Number: 466218N) and Dowel Pins (Jabiru Part Number: PH4A068N) to the airplanes in their fleet which were not equipped with propeller dowel pins.

Jabiru Aircraft Pty. LLC

- On October 1, 2013, Jabiru Aircraft advised the NTSB that they would be expanding guidance regarding extended running at low rpm / high altitude, in their "Alcohol, Lead, Compression Ratio: Fuel Guidance" (Service Letter JSL 007-4) to help preclude lead build up in Jabiru engines. This guidance will also extend to airplanes operating in the Light Sport Aircraft (LSA) categories through Safety Directive JSDL 007-4 which was prepared to allow application of JSL007-4 to aircraft operating within the LSA categories.

- On October 11, 2013, Jabiru Aircraft advised the NTSB, that in the next revision of the Jabiru Engine Overhaul Manual (JEM0001) the guidance would include:

1. Directions specifying that when installing the propeller flange, application of the retaining compound should be limited to within the bore of the female thread in the crankshaft.

2. A requirement that care be taken to ensure there is no excess retaining compound between the capscrew's washer and the propeller flange during installation.

3. A recommendation for owners that if not so equipped, to upgrade their engines to include propeller flange dowels during the overhaul. TESTS AND RESEARCHMaintenance Records Review

According to aircraft maintenance records, the valves and valve seats had been reground / recut at 204 hours total engine operating time. The sparkplugs had been replaced at 451.6 hours. On August 5, 2012, approximately 11 days prior to the accident, at 510.8 hours total engine operating time, the exhaust gas temperature (EGT) probes were inspected.

Engine Examination

Examination of the engine by Jabiru Pacific LLC revealed that the capscrews which held the propeller flange extension on to the engine crankshaft appeared to have sheared off. Further examination revealed that the top of the engine case under the starter near the No. 6 cylinder was disfigured. Attempts to rotate the drive train in both a clockwise direction and counterclockwise direction were unsuccessful, indicating that the engine was seized internally.

Examination of the No. 1, No.2, No.3, No. 4, and No. 5 cylinder heads, pushrods, barrels, pistons, and connecting rods revealed no evidence of any preimpact anomalies or failures which would have precluded normal operation of the engine. However, examination of the No. 6 cylinder head revealed that significant damage was present, and it was discovered that the exhaust valve and valve seat were missing. Examination of the No. 6 cylinder also revealed that the piston was lying in the bottom of the cylinder, along with the wrist pin which was broken into two pieces. Both pieces displayed evidence of impact damage and fracturing. The No. 6 connecting rod was visibly connected to the crankshaft but, it was bent almost in half and wedged between the crankshaft and the top of the engine case indicating that it was the source of the internal seizure as it prevented rotation of the crankshaft.

Examination of the contents of the oil pan revealed more shattered portions of the No. 6 piston, as well as parts of the piston rings, and the exhaust valve head.

Examination of the exhaust system also revealed that parts of the exhaust valve seat had been captured in the muffler. Examination of the valve seat revealed that it had fragmented into two main pieces along with numerous smaller fragmented ones.

Materials Laboratory Component Examination

Examination of the engine components by the NTSB Materials Laboratory Division confirmed that the No.6 cylinder exhaust valve seat had dislodged from its seat and had fractured into multiple fragments. Examination of the fragments under a stereomicroscope revealed that they had a rough appearance which was consistent with overstress fractures. The compression face of the No. 6 cylinder head also exhibited multiple impact marks.

Evidence of lead like deposits was discovered during visual examination of the No.6 cylinder exhaust. These deposits were later confirmed to be lead using energy dispersive spectroscopy (EDS). Examination of the other cylinders and pistons also revealed the presence of lead deposits on those components as well.

The cylinder valve and rocker arm assemblies were designed to incrementally rotate the valves with each cycle of the rocker arms. Examination of the No. 6 rocker arm shaft and exhaust valve rocker arm bushing exhibited features consistent with abrasive wear. Circumferential wear marks were observed on the shaft and a step could be felt by hand where the bearing had been articulating against the shaft. On the bushing, the wear had progressed through the bearing material into the steel backing material. Lesser wear marks were observed on the intake rocker arm bushing and the corresponding location on the shaft. When the valve stems were removed from the valve guides, metal particulates could be seen on the stems.

Measurements taken using a caliper of the No. 6 exhaust valve spring indicated that the exhaust valve spring free ...