20180102000389A

ON JANUARY 2, 2018, ABOUT 0920, A CESSNA T210L, N2122S, WAS SUBSTANTIALLY DAMAGED DURING LANDING FOLLOWING A RIGHT MAIN LANDING GEAR COLLAPSE AT (UAO), AURORA, OREGON. THE PRIVATE PILOT AND^PRIVACY DATA OMITTED^OF THE AIRPLANE WAS NOT INJURED. VISUAL METEOROLOGICAL CONDITIONS PREVAILED AT THE TIME OF THE ACCIDENT. THE CROSS-COUNTRY FLIGHT WAS BEING OPERATED IN ACCORDANCE WITH TITLE 14 CODE OF FEDERAL REGULATIONS PART 91, AND A FLIGHT PLAN WAS NOT FILED. THE FLIGHT DEPARTED PAINE FIELD (PAE), EVERETT, WASHINGTON, ABOUT 0758, WITH UAO AS ITS DESTINATION.

THE PILOT REPORTED THAT WHILE ON DOWNWIND FOR RUNWAY 35 AT UAO, HE ACTIVATED THE LANDING GEAR EXTENSION LEVER, WHICH WAS FOLLOWED BY THE ORANGE LIGHT GOING OUT, HOWEVER, THE GREEN [DOWN AND LOCKED] LIGHT DID NOT ILLUMINATE. THE PILOT FURTHER REPORTED THAT THE GEAR APPEARED TO BE DOWN. HE THEN REQUESTED PERMISSION TO PERFORM A LOW FLY-BY THE CONTROL TOWER, SO THE CONTROLLER COULD OBSERVE THE POSITION OF THE LANDING GEAR; THE CONTROLLER CONFIRMED THAT THE LANDING GEAR APPEARED TO BE DOWN, FOLLOWED BY CLEARING THE PILOT FOR A LEFT DOWNWIND APPROACH AND LANDING. THE PILOT STATED THAT WHILE ON DOWNWIND HE ATTEMPTED TO RAISE AND LOWER THE LANDING GEAR, HOWEVER, WHILE THE ORANGE LIGHT WOULD ILLUMINATE, INDICATING THAT THE LANDING GEAR HAD RETRACTED, THE GREEN LIGHT WOULD NOT. THE PILOT OPINED THAT THE GEAR APPEARED TO BE DOWN AS VIEWED FROM THE AIRPLANE?S LANDING GEAR MIRROR. SHORTLY AFTER TOUCHDOWN THE RIGHT MAIN LANDING GEAR COLLAPSED, WHICH CAUSED THE AIRPLANE TO SWERVE RIGHT INTO A GRASSY/MUDDY SAFETY AREA. THE AIRPLANE CAME TO REST ON ITS LEFT MAIN LANDING GEAR, NOSE GEAR AND RIGHT WING TIP. THE RIGHT HORIZONTAL STABILIZER AND ELEVATOR SUSTAINED SUBSTANTIAL DAMAGE. THE PILOT STATED THAT HE DID NOT ATTEMPT TO LOWER THE LANDING GEAR MANUALLY AS DESCRIBED BY THE PILOT?S OPERATING HANDBOOK (POH).

A POST-ACCIDENT EXAMINATION OF THE LANDING GEAR SYSTEM WAS PERFORMED ON JANUARY 8, 2018, AT AURORA STATE AIRPORT, AURORA, OREGON. THE RESULTS OF THE EXAMINATION REVEALED THE FOLLOWING:

THE LANDING GEAR HYDRAULIC LINES, ELECTRICAL WIRES, ACTUATORS, LOCKS, VALVES AND OTHER LANDING GEAR SYSTEM COMPONENTS WERE VISUALLY INSPECTED, WITH NO ANOMALIES NOTED.

THE HYDRAULIC SYSTEM FLUID WAS VISUALLY INSPECTED, WITH THE LEVEL ABOVE THE ADD MARK AS INDICATED ON THE RESERVOIR DIP STICK. THERE WERE NO OBVIOUS HYDRAULIC LEAKS OBSERVED FROM ANY SPECIFIC HYDRAULIC COMPONENT.

THE LANDING GEAR SWITCH HANDLE WAS IN THE GEAR DOWN POSITION, AND ALL THREE LANDING GEAR WERE VISUALLY AND PHYSICALLY CONFIRMED TO BE IN THE DOWN AND LOCKED POSITIONS. THE LANDING GEAR DOWN LOCK ACTUATORS WERE BOTH EXTENDED, AND THE LOCKS THEMSELVES WERE OVER THE LOCK PINS IN A POSITION APPROPRIATE TO ?LOCKED? IN THE DOWN POSITION, AND WITH VISUALLY CONFIRMED ENGAGEMENT.

WITH THE AIRPLANE POSITION ON THE GROUND AND RESTING ON ITS LANDING GEAR, THE GREEN GEAR DOWN INDICATOR ILLUMINATED WHEN THE MASTER SWITCH WAS POSITIONED TO ON; THE HYDRAULIC POWER PACK RAN FOR ABOUT ONE (1) SECOND BEFORE THE LIGHT CAME ON.

THE AIRPLANE WAS PLACED ON JACKS USING TRIPOD JACKS, WING-MOUNTED JACK ADAPTERS, AND A WEIGHTED TAIL STAND. THE LANDING GEAR WAS RETRACTED AND EXTENDED EIGHT (8) CYCLES OVER A PERIOD OF ABOUT 40 MINUTES, AND FUNCTIONED AS DESCRIBED IN THE CESSNA T210L MM, WITH POSITIVE DOWN LOCK ENGAGEMENT. A GREEN GEAR DOWN LIGHT INDICATION WAS FOLLOWED BY THE HYDRAULIC PUMP SHUTTING OFF. BOTH RETRACTION AND EXTENSION CYCLES WERE COMPLETED IN APPROX EIGHT (8) SECONDS. EACH OF THE CYCLES RESULTED IN A NORMAL GEAR RETRACTION AND EXTENSION CYCLE COMPLETION, WITH ONLY SLIGHT INCREASES IN CYCLE TIMES WHEN THE LANDING GEAR WAS DE-SYNCHRONIZED BY APPLICATION OF RESISTANCE TO ONE OR THE OTHER GEAR LEGS. ADDITIONALLY, THE LG WARNING HORN SYSTEM WAS TESTED FOR PROPER OPERATION, WITH NO ANOMALIES NOTED DURING THE FUNCTIONALITY CHECK. ALL SYSTEMS OPERATED NORMALLY. THE INVESTIGATION FAILED TO REVEAL WHAT PRECIPITATED THE COLLAPSE OF THE GEAR.