ERA18TA263

The private pilot/owner of the experimental, amateur-built airplane reported that, about 15 minutes into the local flight, the engine started "skipping" before completely losing power. He then set up for a forced landing to an open area. During the descent, he maneuvered to clear power lines. The airplane touched down at a steep descent angle, nosed over, and came to rest inverted, which resulted in substantial damage to the airframe. The airplane's engine used an electronic control unit instead of magnetos and required at least one of the airplane's two onboard batteries to provide electrical energy to the ignition system for the engine to operate. Postaccident examination of the airplane revealed that both of its batteries were discharged. After the batteries were charged, the engine was started and ran normally. The alternator also charged the batteries normally. The cockpit instrument panel switch that enabled the alternator to supply energy to the airplane's electrical system, and thus charge the airplane's batteries, was unlabeled. When the switch was placed in the unlabeled on position, the alternator field wire received power and the alternator charged normally. The pilot reported that he may have inadvertently left it in the off position during the flight. With the switch in this position, the engine would have continued to run until the selected battery lost its charge. The pilot also reported that he did not use a checklist when operating the airplane. It is likely that the pilot failed to activate the airplane's alternator, which resulted in a discharge of the selected battery during the 15-minute flight. The subsequent loss of electrical power eventually resulted in the total loss of engine power. Additionally, the airplane was not equipped with an alternator warning light as recommended by the engine manufacturer. Had the airplane been equipped with such a light, the pilot might have realized that he had failed to turn the alternator on and that it was not providing energy to the electrical system to sustain the charge of the selected battery.

On September 23, 2018, about 1545 eastern daylight time, a Zenith Aircraft Company CH 750, N752VK, was substantially damaged following a forced landing near DeLeon Springs, Florida. The private pilot and one passenger sustained minor injuries. The airplane was operated by the pilot under the provisions of Title 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed, and no flight plan was filed for the local flight that originated from DeLand Municipal Airport (DED), DeLand, Florida, about 1530.The pilot/owner reported that while over the DeLeon Springs area, the engine started "skipping." The engine then lost all power and the propeller stopped. He set up for a forced landing to an open area. During the descent, he observed power lines and maneuvered to clear them. The airplane touched down at a steep descent angle. After touchdown, the airplane nosed over and came to rest inverted. An inspector with the Federal Aviation Administration responded to the accident site and examined the wreckage. He reported that the engine firewall, wings, and vertical stabilizer had structural damage. Further examination of the wreckage revealed that the airplane was equipped with two 12v motorcycle batteries, and both were discharged. One battery indicated 0.75 volts and the other indicated 7 volts. Both batteries were then charged by the inspector and a mechanic, who were then able to start the airplane's Viking 110 engine normally. The alternator was found to be charging normally with the engine running and the bus voltage was greater than 13.5 volts. The key-actuated rotary (ignition) switch on the cockpit instrument panel controlled the airplane's alternator and started the airplane's engine was unlabeled. When the switch switch was placed in the unlabeled on position, the alternator field wire received power and the alternator charged normally. When placed to the unlabeled off position, power was removed from the alternator field wire, and the engine continued to run as long as one of the unlabeled battery toggle switches was turned on. The Viking 110 engine manual recommended an alternator warning light installation; however, the inspector noted that there was no light installed. The pilot reported to the FAA inspector that he may have left the alternator switch in the unlabeled off position by mistake. The pilot also reported that he did not utilize a checklist when operating the airplane. The Viking 110 engine manual reminds operators that the engine is controlled by an electronic control unit (ECU) versus mechanically operated magnetos and at least one battery must maintain its charge for the engine to operate.