Summary
We propose to supersede an existing airworthiness directive (AD) that applies to certain Cessna Aircraft Company (Cessna) Models 172R and 172S airplanes. The existing AD 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 proposed AD would retain the actions of the current AD and add S/Ns to the Applicability section of the AD. Chafing of the fuel return line assembly could lead to fire. We are proposing this AD to correct the unsafe condition on these products.