Airworthiness Directives; Precise Flight, Inc. Models SVS I and SVS IA Standby Vacuum Systems

The FAA adopts a new airworthiness directive (AD) for all airplanes equipped with Precise Flight, Inc. (Precise Flight) Models SVS I and SVS IA standby vacuum systems (SVS) installed under certain supplemental type certificates or through field approval. This AD requires you to replace the airplane flight manual supplement (AFMS) in the airplane flight manual with the appropriate revision and install placards as defined in the AFMS, upgrade the Model SVS I or SVS IA SVS to the Model VI SVS, and add the instructions for continued airworthiness (ICA) to the maintenance schedule for the aircraft. This AD results from several reports of failed shuttle control valves of the standby vacuum system (SVS) and one report of an airplane crash with a fatality in which improper use of the SVS was a factor. We are issuing this AD to correct problems with the SVS before failure or malfunction during instrument flight rules (IFR) flight that can lead to pilot disorientation and loss of control of the aircraft.