Airworthiness Directives; Cessna Aircraft Company Airplanes

We are superseding an existing airworthiness directive (AD) for certain Cessna Aircraft Company (Cessna) Models 172R and 172S airplanes. That AD currently requires you to inspect the fuel return line assembly for chafing; replace the fuel return line assembly if chafing is found; and inspect the clearance between the fuel return line assembly and both the right steering tube assembly and the airplane structure, adjusting as necessary. Since we issued that AD, we have received a field report of a fuel return line chafing incident on a Cessna Model 172 airplane with a serial number (S/N) that was not included in the AD. This AD retains the actions of the current AD and adds S/Ns to the Applicability section of the AD. Chafing of the fuel return line assembly could lead to fire. This new AD requires the actions of the current AD and adds S/Ns to the Applicability section of the AD. We are issuing this AD to correct the unsafe condition on these products.