Date:	Thursday 16 August 2012
Time:	08:39
Type:	Ridge Jaybird
Owner/operator:	Patriot Technologies Group, LLC
Registration:	N365R
MSN:	201
Year of manufacture:	2005
Total airframe hrs:	915 hours
Engine model:	Jabiru 3300
Fatalities:	Fatalities: 0 / Occupants: 2
Aircraft damage:	Substantial
Category:	Accident
Location:	In Gull Lake in the Herkimer County town of Webb, NY -   United States of America
Phase:	En route
Nature:	Unknown
Departure airport:	Burlington, VT (BTV)
Destination airport:	Rome, NY (RME)
Investigating agency:	NTSB
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
While climbing to 6,500 feet mean sea level, about 45 minutes into the flight, the engine began to run rough “like it was developing carburetor ice,” so the pilot applied carburetor heat, since the meteorological conditions were conducive to carburetor ice. The engine, however, continued to run rough and began to “cough” like it was starved of 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 the other crewmember began the checklist, the propeller came off the airplane, struck the right side of the cowling, struck the right lift strut, and fell away. The pilot then declared an emergency with air traffic control, began evaluating landing sites, and elected to ditch in a nearby lake.
Examination of the wreckage revealed that the entire propeller assembly, including the propeller spinner and propeller flange extension, had separated from the propeller flange, which was part of the forward portion of the engine crankshaft. Examination of the engine revealed that the bolts that held the propeller flange extension onto the engine crankshaft had sheared off and that the No. 6 cylinder exhaust valve and valve seat were missing from their installed positions. Further examination revealed that the exhaust valve head had come to rest in the oil pan, and parts of the exhaust valve seat had been captured in the muffler.
Examination of the No. 6 cylinder exhaust valve revealed that the valve stem had fractured near the transition from the head radius to the cylindrical stem and that lead deposits were on the stem next to the fracture. Multiple ratchet marks were present around the perimeter of the stem. The presence of the ratchet marks and the fracture surface were consistent with fatigue crack initiation and propagation. Examination of the other cylinders and pistons also revealed the presence of heavy lead deposits, which can act as an insulating layer and can interfere with the normal heat transfer process; such deposits indicate that the engine may have been run at some point at excessively high temperatures.
According to the engine manufacturer, they were aware of about eight previous in-service failures of exhaust valves. They advised that the exhaust valves appeared to be intolerant of temperatures over about 750 degrees C and that heat stress was the most common issue that they had identified. They further advised that around that temperature, the exhaust valve would start showing indications of stress corrosion/cracking at the base of the stem.
Examination of the crankshaft revealed that it had six evenly spaced threaded holes and three smooth bored holes. Each threaded hole contained the shank of a capscrew that had fractured flush with the face of the forward end of the crankshaft. The three smoothed-bored holes showed no evidence of them containing anything that had been inserted or installed in the bore. The fracture faces on the capscrews had a smooth appearance with smear marks orientated in the direction of rotation, which are consistent with an overstress fracture in shear.
According to the manufacturer, at the time of the accident, they had identified about 8 instances where the propeller flange attachment had separated from airplanes due to varying circumstances. To alleviate some of the problems that they observed, they took several steps ensure that a flange would be properly installed. These steps included issuing two service bulletins and changes to the configuration of new engines to have the longer flange as standard. They also altered the maintenance requirements of the engine for more detailed monitoring of the propeller flange area, and altered the design of the engine to incorporate three 8mm dowels between the crankshaft and the propeller flange; in July 2011, they began including these propeller flange dowels into the engines.
Comparison of the engine’s propeller flange to other propeller flanges
Probable Cause: A failure of an engine cylinder exhaust valve due to the buildup of lead deposits on the valve stem and fatigue cracking of the valve stem, resulting in a total loss of engine power, and the loss of the propeller. Contributing to the accident was the lack of design standards or guidance for assembly and maintenance of light sport aircraft.

NTSB
FAA register: http://wamc.org/post/two-safe-after-small-plane-crash-adirondack-lake
[LINK NOT WORKING ANYMORE:http://www.wwnytv.com/news/local/Air-Force-Helicopters-Rescue-Occupants-Of-Downed-Aircraft.html]
https://www.faa.gov/data_research/accident_incident/preliminary_data/events01/media/08_365R.txt
http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=365R

https://flightaware.com/live/flight/N365R
http://wamc.org/post/two-safe-after-small-plane-crash-adirondack-lake
[LINK NOT WORKING ANYMORE:http://www.wwnytv.com/news/local/Air-Force-Helicopters-Rescue-Occupants-Of-Downed-Aircraft.html]
https://www.faa.gov/data_research/accident_incident/preliminary_data/events01/media/08_365R.txt
http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=365R

https://flightaware.com/live/flight/N365R

Date/time	Contributor	Updates
17-Aug-2012 01:31	gerard57	Added
17-Aug-2012 17:58	vvvww	Updated [Time, Aircraft type, Departure airport, Destination airport, Source, Narrative]
18-Aug-2012 00:02	Gene	Updated [Time, Aircraft type, Registration, Cn, Operator, Location, Nature, Departure airport, Destination airport, Source, Narrative]
21-Dec-2016 19:28	ASN Update Bot	Updated [Time, Damage, Category, Investigating agency]
28-Nov-2017 13:18	ASN Update Bot	Updated [Operator, Other fatalities, Nature, Departure airport, Destination airport, Source, Narrative]