Ultralight
Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Flight Instructor
Flight Crew Last 90 Days 75; Flight Crew Total 10300; Flight Crew Type 25
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Gear Up Landing; Ground Event / Encounter Ground Strike - Aircraft
Flight Crew Returned To Departure Airport
Aircraft
During flight testing of an experimental; retractable gear aircraft; the landing gear failed to extend.  The failure was first noted at 2;500 feet AGL while configuring for landing stalls.  The left main gear failed to lock down; as noted by the left main gear indicator light remaining red.  The gear would retract normally.  Several attempts at extension were made; including during pitch and yaw; to no avail. Manual extension of the gear was attempted following POH (Pilots Operating Handbook) checklist procedures; but the manual pump handle would not move. The decision was made; as recommended by the POH emergency procedure; to land with all gear retracted.  The aircraft returned to the airport of origin; which also had a grass runway.  Landing was made with full flaps at stall speed; and slid about 250 feet in the grass before stopping. There were no injuries to the single occupant of the aircraft.
Ultralight pilot during flight test of retractable gear aircraft reports on gear up landing.