NTSB Factual Report

On January 25, 2003, at 1210 Pacific standard time, a Cessna T210L, N732DK, experienced a collapse of the right main landing gear during a precautionary landing at El Monte, California. The airplane, owned and operated by the pilot under the provisions of 14 CFR Part 91, sustained substantial damage. Neither the private pilot nor the pilot-rated passenger was injured. The personal cross-country flight departed from Cable Airport, Upland, California, at 1015, en route to Camarillo, California. Visual meteorological conditions prevailed, and no flight plan had been filed.

In a written statement, the pilot reported that they had just picked up the airplane from a facility at the Cable airport after it had been there for 6 weeks, getting interior and avionics work done. This was the first flight after completion of the work. After a thorough preflight and run-up, they departed for the Camarillo airport.

In a telephone interview immediately following the accident, the pilot reported that he encountered no discrepancies with the electrical system while en route to Camarillo. There was no discharge indication on the ammeter,

As the flight neared Camarillo, the pilot requested and received a clearance into the traffic pattern. He had just put the landing gear switch in the down position and was reaching for the flaps when the airplane lost all electrical power. The pilot reported that the power loss was sudden, and there had been no prior indications of a decreasing electrical power reserve such as dimming lights and fading or unreadable radios. The pilot circled and attempted to rectify the problem without success. He then decided to return to the El Monte airport, the airplane's base. Using a handheld VHF transceiver, the pilot notified the Camarillo tower of the problem, and then proceeded to the El Monte airport.

As they entered the runway 19 traffic pattern at El Monte, the pilot and passenger visually examined the position of the main gear. Both right and left main gear appeared to be in the down and locked position. The pilot then extended the hand pump and tried to pump it a few times and felt strong resistance from the system. About 2 seconds after touchdown, the airplane shuddered and then veered right off the runway. After exiting the airplane, the pilot noticed that the right main landing gear had folded under the fuselage. A recovery crew lifted the airplane by a sling, and manually extended the right main gear into the down and locked position, where it remained during towing operations back to the pilot's hangar.

In the emergency procedures section of the Pilot's Operating Handbook for the Cessna T210L, the procedure for a landing gear failure to extend reads in pertinent part, "Emergency Hand Pump -- Extend Handle and Pump (perpendicular to handle until resistance becomes heavy --- about 35 cycles)."

Federal Aviation Administration (FAA) inspectors from the Los Angeles Flight Standards District Office examined the airplane. All electrical connections, including the battery, were tight, and they found no evidence of a short circuit. They removed the voltage regulator for functional testing.

An avionics technician from Kim Davidson Aviation, Inc., examined the electrical system under the auspices of the FAA inspector on February 6, 2003. The battery and alternator functioned on a split switch. He turned the alternator on and off several times and noted fluctuations between 3 to 5 ohms in the readings. The avionics specialist stated that the contact on the alternator switch, over time, loses its function. This results in a lack of field current and eventual complete discharge of the battery. The indications of the impending failure, such as intermittent radios, are not discovered until the voltage on the battery voltage has decreased to a low level.

NTSB Probable Cause

the alternator switch contact failure, which resulted in a complete electrical failure.