An AD issued last month requires operators of certain Gulfstream IV-SP series to install software and hardware updates to their Honeywell Primus Epic avionics to correct an EFIS display blanking problem. The FAA said it received a report that all four EFIS screens went blank simultaneously for about 74 seconds in flight. Two similar incidents occurred on the ground, according to the agency. The directive (AD 2005-04-06) requires compliance within 50 flight hours of February 23.