20110527012289I

On may 27, 2011, the subject aircraft was repositioned from savannah/hilton head international airport,savannah, ga (ksav) to greenville spartanburg international airport, greer, SC (kgsp). The aircraft had just been released from maintenance at the Gulfstream facility in savannah where, among other things it had a landing gear selector rod end replaced. The aircraft functioned normally on the repositioning leg. The aircraft departed kgsp bound for westchester county airport, white plains, NY (khpn) at approximately 0725 EDT. This leg of the flight was operated under 14 CFR part 91K with one passenger on board. The crew stated that on approach to khpn the landing gear was selected down and the normal gear noises were heard but the landing indication was three red lights, gear unsafe. The approach was aborted and the crew requested a holding area from ATC to run checklists. Approximately 20-40 seconds later, the r hyd overheat eicas message illuminated. The right hydraulic temperature was 85 degrees and amber. Right hydraulic pressure was between 1400-1500 PSI where it remained for the rest of the flight. Normal hydraulic pressure is 3000 PSI. The hydraulic overheat checklist was run and the decision was made to divert to Stewart International Airport, newburgh, NY (kswf) due to its 11,000 foot runway and low traffic density. The emergency landing gear extension checklist was run and a blow down was initiated. After the blow down the nose gear indicated green (safe) and the mains still red (unsafe). A fly-by of hpn tower indicated that all three gear appeared to be down. A divert to swf was requested and approved. Enroute to swf, an emergency was declared due to the unsafe gear and the right engine at idle power (per the hydraulic overheat checklist). The captain stated that enroute to swf, the hydraulic failure checklist was reviewed in the event that a complete failure was experienced. A normal approach was made and emergency brakes were selected on short final. The aircraft touched down on rwy 27 approximately 300 feet beyond the touchdown zone marker. All three landing gear remained down for the first 700-800 feet of the landing roll at which time the right hand main landing gear collapsed. The aircraft maintained centerline and came to rest on the nose gear, left main gear and right wingtip at approximately the 6000 foot mark. All four main landing gear tires were flat spotted and blown out. The damage to the aircraft appears to be confined to the underside of the right wingtip with no structural or flight control damage apparent. The two crew and one passenger evacuated the aircraft without injury. Investigation by the FAA, aircraft manufacturer and aircraft operator did not reveal a definitive cause for the failure of the main landing gear to achieve a down and locked condition. With the aircraft in the hangar on jacks, gear retraction tests, with both normal and emergency extensions, resulted in normal operation of the landing gear (down and locked), with the associated cockpit indication, each time. Should additional information as to cause become available, this report will be amended.