Gulfstream IV / G350 / G450
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Critical
Flight Crew Diverted; General Declared Emergency
Aircraft
While at FL400 in cruise the left engine TGT spiked to over 990; went back to normal and then spiked again. There were no changes in HP or LP Fan speed; fuel flow or thrust changes. The left engine power lever was moved to idle and no more TGT spikes were observed. We completed all QRC; QRH and AOM check lists; declared an emergency with ATC and requested a diversion to a nearby airport. After holding for 15 minutes to burn off fuel we conducted a normal landing and taxied to the airport FBO.
A GLF IV noted spiking left engine TGT; unaccompanied by other engine instrument anomalies. The flight crew declared an emergency and diverted to a nearby airport.