Federal Aviation Administration February 16, 2005 – Federal Register Recent Federal Regulation Documents

The FAA is adopting a new airworthiness directive (AD) for all Saab Model SAAB SF340A and SAAB 340B series airplanes. This AD requires a one-time inspection to determine the part and serial numbers of certain engine vibration isolators (mounts) and the cure dates of certain molded assemblies incorporated in those engine mounts; and related corrective actions if necessary. This AD is prompted by a report that disbonding of the elastomer from the inner metal core and shim of certain engine vibration mounts has occurred within a few hundred hours of operation, causing heavy chafing of the engine support system and chafing of the fire sensor loop. We are issuing this AD to prevent reduced integrity of the fire-shielding capacity of the nacelle structure and a possible fire detector fault.

The FAA is adopting a new airworthiness directive (AD) for certain Gulfstream Model GV-SP series airplanes. This AD requires repetitive inspections of the avionics standard communication bus (ASCB) for any noise interference and repair of the ASCB if noise interference is found. This AD also requires revisions of the airplane flight manual (AFM) to prohibit dispatch of any flight with the integrated standby flight display (SFD) inoperative; to add procedures to facilitate recovery of the cockpit display units in the event that the cockpit displays go blank; and to add flightcrew briefings on the use of standby instruments in case the cockpit display units go blank and do not recover. This AD also requires installing an avionics software update and a hardware upgrade to the Honeywell Primus Epic system to correct a display blanking problem; installing the update will allow removal of certain AFM revisions and will end the repetitive inspections of the ASCB. This AD is prompted by a report indicating that all four cockpit flight panel displays went blank simultaneously. We are issuing this AD to prevent a software error from blanking the cockpit display units, which will result in a reduction of the flightcrew's situational awareness, and possible loss of control of the airplane. We are also issuing this AD to address noise interference in the ASCB, which can interfere with the display recovery after a blanking event and consequently extend the time that the displays remain blank. In addition, we are issuing this AD to ensure that the flightcrew is advised of the procedures necessary to address blank cockpit display units.