On November 21, 2005, at approximately 0600 Pacific standard time, a Gulfstream Aerospace, G-5, N225GV, was not damaged following a right main landing gear door sequencing failure near Portland-Hillsboro Airport (KHIO), Hillsboro, Oregon. The airline transport pilot, the airline transport co-pilot, the cabin attendant, and four passengers were not injured. Nike Inc. was operating the flight under Title 14 CFR Part 91. Visual meteorological conditions prevailed for the cross-country business flight which was originating at the time of the event. An IFR flight plan had been activated with a destination of Toronto, Canada. The pilot said that as they raised the landing gear on takeoff, the right main landing gear (MLG) door did not retract. He said that the checklist instructed him to cycle the landing gear; when he cycled the landing gear, the right MLG became jammed in the half down position. The pilot performed a low fly-by, and maintenance personnel on the ground photographed the bottom of the airplane. Gulfstream Aerospace engineers reviewed the photograph and advised the pilot in how to extend the landing gear. The pilot was then able to extend the landing gear. Six hours and ten minutes after takeoff, the airplane landed successfully. Post-incident examination of the right MLG revealed a black/rubber skid mark on the inside of the MLG door; the skid mark terminated at a row of 27 bolts which hold a gap seal in place. The outboard tire of the right MLG truck exhibited seven evenly spaced gouges which matched the spacing of the gap seal bolts. The MLG door uplock linkage bungee/actuator's (P/N 1159L50903-1) exterior exhibited advanced exfoliating corrosion.