Narrative:

Report of off airport landing.on a VFR flight I experienced; what was believed to be a possible mechanical discrepancy concerning my experimental amateur built airplane. As a result; I successfully accomplished a precautionary off-airport landing. At that instant; the following facts known to me:-I was flying an experimental aircraft that I had just completed building this year (my first build);-I had only approximately 70 hours on the experimental engine; propeller; airframe and its systems;-I had recently replaced an exhaust gas temperature (egt) probe; which had been indicating spiking redline temperatures;-the aircraft engine is powered by experimental dual electronic ignitions; which rely entirely on voltage from the experimental earthx lithium polymer (lipo) battery ('primary battery');-I had recently replaced the experimental primary battery because it had failed completely (on the ground);-the failed battery and its replacement battery are designed to shutoff - completely (zero voltage) at 11 volts; -unlike a lead acid battery; which will fail slowly; but continue to feed electricity to the electronic ignition modules and keep the engine running; the earthx lipo battery would cause immediate engine failure at 11 volts.further; compounding my decision to perform an emergency precautionary off-airport landing were the following factors:-I was traveling over an area of dense forest with no visible safe landing spot (i.e. Farm fields; roads; etc.).-the first safe off-airport landing spot I saw was a sandbar; with some grass; no trees or rocks. It appeared to be an adequate location to land where I could assess the airplane on the ground; rather than in the air.-I had no knowledge that it was a reservoir; much less a major source of fresh water for the state. My primary concern was to get the airplane on the ground; safely; and not continue flying with a possible unknown mechanical discrepancy.the landing was uneventful; until I felt the wheels sink into the sand on the final few feet of the ground roll. I stopped; and then tried adding full power; but the airplane teetered over so I shutdown the engine and jumped out. I discovered the sand was a lot softer than I had anticipated; sinking to my ankles. After digging out sand in front of the tires; I started the engine; again; to attempt to taxi to dryer sand; only to make it approximately 100-200 feet before the wheels dug-in; again. At that time; I shut down the engine. I dug out the wheels and restarted the engine and gave it full power to try to move; but this time no movement.to avoid further complicating the situation and risk damage to the aircraft; I shut down the engine to reassess the situation. About ten to fifteen minutes after landing; a law enforcement helicopter arrived and circled for few minutes. I attempted to hail them on the emergency channel (121.5); but was unsuccessful. I called the law enforcement dispatch via my cellphone and informed the operator that I was the pilot on the sand bar looking at the helicopter.when the helicopter landed; a crewmember approached me and asked for my paperwork (license; medical; etc.); which I supplied. He asked me why I had landed on the sand bar and I told him it was a precautionary landing.

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Original NASA ASRS Text

Title: Experimental aircraft pilot reported making a precautionary off-airport landing; subsequently getting stuck on a sandbar.

Narrative: Report of off airport landing.On a VFR flight I experienced; what was believed to be a possible mechanical discrepancy concerning my experimental amateur built airplane. As a result; I successfully accomplished a precautionary off-airport landing. At that instant; the following facts known to me:-I was flying an Experimental Aircraft that I had just completed building this year (my first build);-I had only approximately 70 hours on the experimental engine; propeller; airframe and its systems;-I had recently replaced an exhaust gas temperature (EGT) probe; which had been indicating spiking redline temperatures;-The aircraft engine is powered by experimental dual electronic ignitions; which rely entirely on voltage from the experimental EarthX Lithium Polymer (LiPo) battery ('primary battery');-I had recently replaced the experimental primary battery because it had failed completely (on the ground);-The failed battery and its replacement battery are designed to shutoff - completely (zero voltage) at 11 volts; -Unlike a lead acid battery; which will fail slowly; but continue to feed electricity to the electronic ignition modules and keep the engine running; the EarthX LiPo battery would cause immediate engine failure at 11 volts.Further; compounding my decision to perform an emergency precautionary off-airport landing were the following factors:-I was traveling over an area of dense forest with no visible safe landing spot (i.e. farm fields; roads; etc.).-The first safe off-airport landing spot I saw was a sandbar; with some grass; no trees or rocks. It appeared to be an adequate location to land where I could assess the airplane on the ground; rather than in the air.-I had no knowledge that it was a reservoir; much less a major source of fresh water for the state. My primary concern was to get the airplane on the ground; safely; and not continue flying with a possible unknown mechanical discrepancy.The landing was uneventful; until I felt the wheels sink into the sand on the final few feet of the ground roll. I stopped; and then tried adding full power; but the airplane teetered over so I shutdown the engine and jumped out. I discovered the sand was a lot softer than I had anticipated; sinking to my ankles. After digging out sand in front of the tires; I started the engine; again; to attempt to taxi to dryer sand; only to make it approximately 100-200 feet before the wheels dug-in; again. At that time; I shut down the engine. I dug out the wheels and restarted the engine and gave it full power to try to move; but this time no movement.To avoid further complicating the situation and risk damage to the aircraft; I shut down the engine to reassess the situation. About ten to fifteen minutes after landing; a law enforcement helicopter arrived and circled for few minutes. I attempted to hail them on the Emergency Channel (121.5); but was unsuccessful. I called the law enforcement dispatch via my cellphone and informed the operator that I was the pilot on the sand bar looking at the helicopter.When the helicopter landed; a crewmember approached me and asked for my paperwork (license; medical; etc.); which I supplied. He asked me why I had landed on the sand bar and I told him it was a precautionary landing.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.