Narrative:

Departed ZZZ airport at XA26 local time for a test flight in a C177RG. Aircraft had been repaired from a previous gear up landing and was being returned to service. The engine was new and needed to be test flown and broken in. The test flight was going well, engine and aircraft were performing normally, flight time was approximately 45 mins. It was getting dark, so I decided to return for landing. My entire test flight had taken place over the airport (ixd) at 3000 ft MSL. I began my descent to pattern altitude (2000 ft MSL). Upon reaching a right midfield downwind to runway 35, I extended the landing gear. Extension was normal, green down light was on. The pattern was flown normally. I planned to land long, as my taxiway exit was at the far end of the field. I carried a little extra power to carry the flare for a long landing. During the flare, I felt the main gear touch slightly, then the airplane rose up a little and began to settle in the flare again. This did not seem out of the ordinary until the tail touched the ground. At this point I realized the nose gear was down, but the main gear had collapsed or free fallen backward during the first touchdown. I continued to fly the aircraft until it came to a full stop. The engine was still running when the aircraft came to a stop. I believe I told the tower we had landed with 'no mains.' then I shut the aircraft off, secured it, and got out. The tower was called on the phone after the aircraft had been exited. At this time, the aircraft has not been inspected due to the inability to jack it without a tail tie-down. Callback conversation with reporter revealed the following information: the reporter stated the aircraft was not jacked and tested until the tail skid was replaced. The reporter said the landing gear is extended and retracted by an electric motor hydraulic pump and when operating is controled by magnetic reed switches. The reporter stated 2 reed switches failed and shut off the motor pump while extending the main landing, but not to the down and locked position. The reporter said the right switch had failed, closed, and the left switch and switch sensor was stuck by grease and dirt. The reporter stated this same gear retract system is used in several other cessna light airplanes, and has caused little trouble. The reporter said the PF and the PNF checked and confirmed several times during the approach that the green light was illuminated. The reporter stated when the airplane was jacked prior to finding the failed switches, the landing gear was cycled with the FAA safety inspectors present and the event was repeated. The reporter said the main gear extended the hydraulic pump shut off and the main gear was extended, but not down and locked.

Related reports:

Google
 

Original NASA ASRS Text

Title: A CESSNA 177RG LANDED WITH THE MAIN LNDG GEAR NOT DOWN AND LOCKED, BUT WITH A GREEN LNDG GEAR POS LIGHT. CAUSED BY 2 FAILED REED SWITCHES.

Narrative: DEPARTED ZZZ ARPT AT XA26 LCL TIME FOR A TEST FLT IN A C177RG. ACFT HAD BEEN REPAIRED FROM A PREVIOUS GEAR UP LNDG AND WAS BEING RETURNED TO SVC. THE ENG WAS NEW AND NEEDED TO BE TEST FLOWN AND BROKEN IN. THE TEST FLT WAS GOING WELL, ENG AND ACFT WERE PERFORMING NORMALLY, FLT TIME WAS APPROX 45 MINS. IT WAS GETTING DARK, SO I DECIDED TO RETURN FOR LNDG. MY ENTIRE TEST FLT HAD TAKEN PLACE OVER THE ARPT (IXD) AT 3000 FT MSL. I BEGAN MY DSCNT TO PATTERN ALT (2000 FT MSL). UPON REACHING A R MIDFIELD DOWNWIND TO RWY 35, I EXTENDED THE LNDG GEAR. EXTENSION WAS NORMAL, GREEN DOWN LIGHT WAS ON. THE PATTERN WAS FLOWN NORMALLY. I PLANNED TO LAND LONG, AS MY TXWY EXIT WAS AT THE FAR END OF THE FIELD. I CARRIED A LITTLE EXTRA PWR TO CARRY THE FLARE FOR A LONG LNDG. DURING THE FLARE, I FELT THE MAIN GEAR TOUCH SLIGHTLY, THEN THE AIRPLANE ROSE UP A LITTLE AND BEGAN TO SETTLE IN THE FLARE AGAIN. THIS DID NOT SEEM OUT OF THE ORDINARY UNTIL THE TAIL TOUCHED THE GND. AT THIS POINT I REALIZED THE NOSE GEAR WAS DOWN, BUT THE MAIN GEAR HAD COLLAPSED OR FREE FALLEN BACKWARD DURING THE FIRST TOUCHDOWN. I CONTINUED TO FLY THE ACFT UNTIL IT CAME TO A FULL STOP. THE ENG WAS STILL RUNNING WHEN THE ACFT CAME TO A STOP. I BELIEVE I TOLD THE TWR WE HAD LANDED WITH 'NO MAINS.' THEN I SHUT THE ACFT OFF, SECURED IT, AND GOT OUT. THE TWR WAS CALLED ON THE PHONE AFTER THE ACFT HAD BEEN EXITED. AT THIS TIME, THE ACFT HAS NOT BEEN INSPECTED DUE TO THE INABILITY TO JACK IT WITHOUT A TAIL TIE-DOWN. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE ACFT WAS NOT JACKED AND TESTED UNTIL THE TAIL SKID WAS REPLACED. THE RPTR SAID THE LNDG GEAR IS EXTENDED AND RETRACTED BY AN ELECTRIC MOTOR HYD PUMP AND WHEN OPERATING IS CTLED BY MAGNETIC REED SWITCHES. THE RPTR STATED 2 REED SWITCHES FAILED AND SHUT OFF THE MOTOR PUMP WHILE EXTENDING THE MAIN LNDG, BUT NOT TO THE DOWN AND LOCKED POS. THE RPTR SAID THE R SWITCH HAD FAILED, CLOSED, AND THE L SWITCH AND SWITCH SENSOR WAS STUCK BY GREASE AND DIRT. THE RPTR STATED THIS SAME GEAR RETRACT SYS IS USED IN SEVERAL OTHER CESSNA LIGHT AIRPLANES, AND HAS CAUSED LITTLE TROUBLE. THE RPTR SAID THE PF AND THE PNF CHKED AND CONFIRMED SEVERAL TIMES DURING THE APCH THAT THE GREEN LIGHT WAS ILLUMINATED. THE RPTR STATED WHEN THE AIRPLANE WAS JACKED PRIOR TO FINDING THE FAILED SWITCHES, THE LNDG GEAR WAS CYCLED WITH THE FAA SAFETY INSPECTORS PRESENT AND THE EVENT WAS REPEATED. THE RPTR SAID THE MAIN GEAR EXTENDED THE HYD PUMP SHUT OFF AND THE MAIN GEAR WAS EXTENDED, BUT NOT DOWN AND LOCKED.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.