What was found
LANDING GEAR UNLOCKED BUT FAILED TO RETRACT AFTER TAKEOFF. ATTEMPS TO EXTEND GEAR TO DOWN AND LOCKED ELECTRICALLY AND MANUALLY WERE UNSUCCESSFUL. GEAR COLLAPSED UPON LANDING. INVESTIGATION REVEALED THAT THE RECENTLY REPLACED WORM AND DRIVE GEARS INSIDE THE LANDING GEAR ACTUATOR WERE WORN AND STRIPPED. THE GEARS WERE REMOVED AND CASE TESTED FOR HARDNESS. TEST RESULTS REVELED THAT THE GEARS WERE SOFT AND BELOW MANUFACTURERS SPECS. SUSPECT GEARS WERE IMPROPER OR NEVER HEAT TREATED. (GL17200303131) (K)