On September 10, 2020, at 0915 eastern daylight time, an experimental amateur-built Vans RV6, N196DJ, was substantially damaged when it was involved in an accident near Melbourne, Florida. The pilot and passenger received minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations (CFR) Part 91 personal flight. The pilot/owner had recently purchased the airplane and reported that it had previously been in long-term storage for about 9 to 10 years without being “pickled or preserved.” The pilot spent several weeks preceding the accident getting the airplane to an airworthy state and addressing minor maintenance issues. This included partially removing the No. 2 cylinder and conducting a borescope inspection of the camshaft and other engine internal components. The visual inspection revealed no corrosion, and the cylinder was reassembled per the engine manufacturer’s specifications. A total of 6 hours were subsequently flown on the engine without issue and as a precautionary measure, an oil change was performed several days prior to the accident. The suction screen was removed and inspected and about 1/2 teaspoon of carbon deposits and sludge was removed. On the day of the accident, the pilot met with a friend and departed on a local flight to practice traffic pattern maneuvers. After the pattern maneuvers, the pilot departed the area and proceeded to an offshore practice area to continue flight maneuvers. Suddenly, the engine started running “very rough” and the pilot increased the mixture. The engine shuddered and came to a “hard stop,” and the propeller was not windmilling. The pilot attempted an engine restart and was able to get about one full propeller rotation before the engine “locked up.” The pilot made a forced landing on a beach and the airplane came to rest inverted, damaging the vertical stabilizer. Following the accident, a visual inspection of the engine after the accident by a Federal Aviation Administration inspector revealed no defects. One quart of residual oil was drained from the engine to check for ferrous metal and no anomalies were noted within the oil, strainer, or filter. The spark plugs were removed, and a breaker bar had to be used to rotate the propeller. Valvetrain continuity was established within the engine. A review of accident photographs revealed that oil was streaked on the underside of the airplane. Due to the scope of the examination, the source of the loss of engine oil could not be determined. The pilot subsequently fully disassembled the experimental engine. During the examination of the internal components, it was discovered that the oil pressure relief spring was corroded, pitted, and broken. The spring was loose within the housing. Overheating and scoring was also observed on the crankshaft journals. A review of the aircraft maintenance logbooks revealed that the engine was last overhauled in 1994, and about 1,490 hours before the accident. According to Lycoming service instruction No. 1009BE, all engine models are to be overhauled within 12 calendar years of the date they first entered service or of last overhaul.