Cessna 210L N59196 accident near Myrtle Beach, South Carolina

Probable cause

A complete loss of electrical power, which resulted from the separation of an alternator wire due to corrosion. Contributing to the accident was the failure of the emergency landing gear extension system due to a lack of hydraulic fluid, which resulted in insufficient pressure to extend the landing gear.

NTSB analysis

The private pilot was conducting a personal cross-country flight. The pilot reported that, shortly after takeoff with the flaps and landing gear retracted, a total loss of electrical power occurred and that he immediately turned back to the departure airport. The landing gear, which is extended and retracted by hydraulic actuators powered by an electrically driven hydraulic power pack, was disabled due to the electrical failure, so the pilot attempted to manually pump the gear down via the emergency gear extension handle; however, after about 10 pumps, it felt like there was no hydraulic pressure in the system. He tried to pump the gear down for about 20 minutes before he realized that the main landing gear (MLG) was not going to extend, and he subsequently landed the airplane with the landing gear unlocked. The pilot said that the landing was smooth and that the MLG initially held the support of the airplane but that it then collapsed. The airplane then skidded to a stop on the runway.

Examination of the engine revealed that the loss of electrical power resulted from the alternator's primary wire being separated from its terminal due to corrosion. Examination of the airplane revealed that one of the MLG actuators had sustained impact damage and was leaking a small amount of hydraulic fluid. No other mechanical issues with the landing gear system were observed.

The Pilot's Operating Handbook recommends that the fluid level in the hydraulic power pack housed within the control pedestal be checked using the dipstick/filler cap every 25 hours and that, if the fluid level is at or below the ADD line on the dipstick, hydraulic fluid should be added. The hydraulic fluid level was examined several days after the accident, and it was observed at the ADD level. The pilot stated that he did not check the hydraulic fluid level before the accident flight but that he did check it the day before and that the level was "ok" at that time. However, given that the pilot was unable to manually extend the landing gear, there likely was insufficient hydraulic fluid in the system to provide the pressure required to manually extend the landing gear. The reason for the lack of hydraulic fluid could not be determined based on the available evidence.

Text from the NTSB. Open the NTSB docket for ERA16LA135 for the full record.