ERA12FA280 · Manzitto Michael A MWLANCAIR 235

About 2 months before the accident, the homebuilt experimental airplane began to experience electrical problems. This was first discovered when the landing gear hesitated before extending. To extend the landing gear during subsequent flights, the pilot shut off all nonessential electrical equipment in the airplane, extended the landing gear, and then turned the electrical equipment back on. On the morning of the accident, while on approach at the destination airport, the electrical system failed and the landing gear would not extend. The pilot reached behind his seat, "jiggled" the airplane's battery cables, and was able to restore electricity and extend the landing gear. He landed the airplane uneventfully and shut the airplane down.

After shutdown, the airplane had to be "hand propped" to be restarted; however, the pilot could not adjust the electrically-controlled propeller to the proper pitch for takeoff. The pilot removed the battery from his airplane and returned to his home airport with another pilot. He charged two batteries and returned with the charged batteries to his airplane. The pilot installed one of the batteries in his airplane and stated that if he could get the airplane started, he would fly it back to his home airport with the landing gear down.

The airplane started after three attempts, and the pilot taxied to the runway. A witness observed fuel exiting the right wingtip fuel vent during taxi, indicating that there was fuel in the main wing tanks. The pilot departed, and while he was en route, he transmitted that he was experiencing a problem and that he was going to land in a field. A witness observed the airplane at low altitude but did not hear any engine noise as the airplane passed him. The airplane then maneuvered around a barn and touched down in a level attitude in a harvested corn field. The airplane’s landing gear collapsed, and the airplane nosed over.

Examination of the airplane and engine revealed no evidence of any preimpact mechanical failure or malfunction; however, examination of the propeller indicated that the engine was not producing power, and the header tank, which supplied fuel to the engine, contained only 8 ounces of fuel. The inline fuel filter and fuel strainer contained only trace amounts of fuel. Further examination revealed that the header tank received its fuel from the wing tanks via electrically-operated transfer pumps. Examination of a connector that connected the positive battery cable to the master relay revealed that the inside of the connector's collar, which had been soldered and crimped onto the battery cable, was moist and heavily corroded, and that not all of the battery cable's wire strands were in contact with the collar of the connector. Further examination revealed that the end of battery cable that had been retained by the connector's collar was also moist and exhibited significant corrosion, indicating that the connector had been exposed to a corrosive environment. Examination of the battery box revealed corrosion and electrolyte (sulfuric acid) residue, which indicated that a release of electrolyte from a previously-installed battery had occurred. Additionally, comparison of the position of the positive battery cable's run from the battery terminal to the master contactor revealed that the master contactor was mounted below the top of the battery and that no precautions had been taken to prevent liquid from running down the cable into the base of the connector.

With a failure of the electrical wiring interconnect, the airplane’s battery was unable to power the electrical system. Because the fuel transfer pumps were electrically powered, fuel was not transferred to the header tank to feed the engine, and a loss of engine power occurred. Additionally, without electrical power, the propeller could not be adjusted and the electrically-actuated landing gear could not be retracted to reduce drag and extend the airplane’s glide. Further, because the wing flaps were electrically operated, they could not be extended during the landing, thus the airplane touched down at a higher speed (13 or more knots) than normal touchdown speed, which reduced the survivability of the accident when the airplane nosed over.

Verbatim NTSB analysis and probable cause from the NTSB dataset