N4943UCessna 210N · 1984

The pilot planned a local flight in order to checkout some recent maintenance work and to charge the battery. He added that the airplane had not been flown over the winter and the battery had lost its charge. The engine was started with the assistance of ground power. After start-up, both alternator out lights on the instrument panel went out indicating to him that they were both on-line. The airplane was equipped with a 28-volt, dual alternator electrical system. The alternator output indicated 29 volts, battery voltage indicated zero, and the ammeter showed that the battery was charging. He conducted the pre-takeoff run-up in accordance with the checklist. All radios and the global positioning system receiver were on and functioning normally prior to takeoff. The pilot reported that at liftoff he raised the landing gear handle, pulled the flap lever up, and reduced to climb power. He reported that "immediately all electrical power went out." The pilot elected to remain in the traffic pattern and return for an immediate landing. He lowered the landing gear handle. However, due to what he perceived as an urgent situation and the attention required by other traffic in the vicinity, he did not use the emergency gear extension procedure to insure that the landing gear was fully down and locked. Upon landing on runway 24 (3,499 feet by 75 feet, asphalt), the main landing gear collapsed and the airplane departed the left side of the runway before coming to rest. The left horizontal stabilizer sustained skin and sub-structure damage. A post accident inspection revealed that the battery had little or no electrolyte in it. Battery output was measured at 8.3 volts, with no indication of electrical current. The alternators and voltage regulators were tested under direct supervision of the Federal Aviation Administration. No anomalies with the function of the alternators or regulators were observed. The Pilot's Operating Handbook (POH) stated that "use of the ground service plug receptacle for starting an airplane with a 'dead' battery or charging a 'dead' battery in the airplane is not recommended." The POH added that a "failure to observe this precaution could result in loss of electrical power during flight." Landing gear extension and retraction is controlled by an electric motor, which provided hydraulic pressure to actuate the gear. Loss of electrical power prevented operation of the motor and required that the landing gear be extended manually. The pilot commented that the accident may have been prevented by inspecting the battery fluid level prior to the flight.