Airworthiness Directives; Cessna Model 750 Airplanes

The FAA is adopting a new airworthiness directive (AD) for certain Cessna Model 750 airplanes. The AD requires repetitive inspections for clearance and chafing of an auxiliary power unit (APU) fuel tube assembly in the tail cone area of the airplane, and corrective actions if necessary. For certain airplanes, this AD also requires replacing the APU fuel line. This AD is prompted by reports of chafed APU fuel tubes leaking into the tail cone area due to interference between the fuel tube assembly and elevator flight control cables, hydraulic lines, and high-temperature bleed air couplings. We are issuing this AD to detect and correct this interference, which could result in chafing, fuel leaking into an area where ignition sources are present, and possible fire in an area without fire detection or extinguishing provisions.