Airworthiness Directives; Gulfstream Aerospace Corporation Airplanes

We are superseding Airworthiness Directive (AD) 2009-17-01, which applied to certain Gulfstream Model G-IV, GIV-X, GV-SP airplanes and Model GV airplanes. AD 2009-17-01 required an inspection for sealant applied to the exterior of the auxiliary power unit (APU) enclosure (firewall), and a revision of the airplane flight manual (AFM), as applicable. This AD requires revising the AFM and revising the applicability to include additional airplanes. This AD was prompted by a report indicating that the type design sealant applied to the APU enclosure failed certain tests. We are issuing this AD to address the unsafe condition on these products.