On April 26, 2003, about 1225 mountain standard time, a Piper PA-46-310P, N189ET, sustained substantial damage when the landing gear was inadvertently retracted while taxiing at Grand Canyon National Park (GCN), Grand Canyon, Arizona. The pilot was operating the airplane under the provisions of 14 CFR Part 91. The private pilot and three passengers were not injured. The personal cross-country flight departed San Diego, California, about 1000 Pacific standard time, en route to Grand Canyon. Day visual meteorological conditions prevailed, and an instrument flight rules (IFR) flight plan had been filed. The pilot reported that while taxiing after a good approach and landing, he raised the flaps, lowered the speed brakes, turned off the landing lights, and switched off the transponder. The landing gear lever was inadvertently raised. Both the nose and right main landing gear collapsed immediately. The airplane came to rest on the left main gear, nose, and right wing. The systems description section of the Federal Aviation Administration approved Pilot Operating Handbook for the airplane was reviewed concerning the landing gear operating system. The cockpit control lever is mechanically linked to the hydraulic sequence valve, which is aft of the rear baggage compartment. A spring loaded electrically operated solenoid gate physically prevents the landing gear handle from being moved out of the down detent when weight is on the landing gear. The solenoid is energized to retract and allow the cockpit gear handle to move when a squat switch on the left main gear strut senses strut extension (liftoff). After the accident, and during repair of the airplane, the landing gear system was examined by Hov-Air, Inc., a maintenance repair facility familiar with the PA-46. The repair shop found that the cockpit gear handle and its linkage (to the hydraulic sequence valve) was out of rigging tolerance. Specifically, the rigging would not allow the gear selector lever handle to be in the full down position where the solenoid gate would block handle movement.