Federal Aviation Administration April 26, 2007 – Federal Register Recent Federal Regulation Documents

The FAA proposes to adopt a new airworthiness directive (AD) for certain Learjet Model 31, 31A, 35, 35A (C-21A), 36, 36A, 55, 55B, and 55C airplanes, and Model 45 airplanes. This proposed AD would require inspecting for unsealed gaps on the pylon side of the engine firewall and cleaning/sealing any unsealed gap; and, for certain airplanes, inspecting for unsealed gaps of the pylon trailing edge and cleaning/sealing any gap. This proposed AD results from a report that unsealed gaps (penetration points) of the engine firewall were discovered during production. We are proposing this AD to prevent penetration of flammable liquids or fire through the engine firewall into the engine pylon, which could lead to fire inside the airplane.

We propose to adopt a new airworthiness directive (AD) for the products listed above. This proposed AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as:

The FAA proposes to supersede an existing airworthiness directive (AD) that applies to all Boeing Model 747-100, 747-100B, 747- 100B SUD, 747-200B, 747-200C, 747-300, 747-400, 747-400D, and 747SR series airplanes. The existing AD currently requires repetitive inspections for cracking of the station 800 frame assembly, and repair if necessary. This proposed AD would revise certain applicabilities and compliance times in the existing AD. This proposed AD results from several reports of cracks of the station 800 frame assembly on airplanes that had accumulated fewer total flight cycles than the initial inspection threshold in the original AD. We are proposing this AD to detect and correct fatigue cracks that could extend and fully sever the frame, which could result in development of skin cracks that could lead to rapid depressurization of the airplane.

This notice proposes special conditions for the Boeing Model 787-8 airplane. This airplane will have novel or unusual design features when compared to the state of technology envisioned in the airworthiness standards for transport category airplanes. The fuselage of the Boeing Model 787-8 series airplane will be made of composite materials rather than conventional aluminum. While the regulations include flame propagation standards for some materials commonly found in inaccessible areas of the airplane, they do not yet incorporate standards for materials used to construct the fuselage. Therefore, special conditions are needed to address this design feature. These proposed special conditions contain the additional safety standards that the Administrator considers necessary to establish a level of safety equivalent to that established by the existing airworthiness standards. Additional special conditions will be issued for other novel or unusual design features of the Boeing Model 787-8 airplanes.

The FAA is adopting a new airworthiness directive (AD) for certain Learjet Model 45 airplanes. This AD requires deactivating the auxiliary power unit (APU), capping/plugging the fuel lines to the APU, and removing the APU fuel shutoff valve. This AD results from reports of fuel leaking from the APU fuel shutoff valve into a flammable fluid fire protection area that is also interconnected with the main landing gear's wheel well bay. We are issuing this AD to prevent fuel leaking from the fuel shutoff valve of the APU, which could result in an uncontrollable fire and adversely affect the airplane's continued safe flight and landing.

The FAA is issuing this notice to advise the public of a first meeting of RTCA Special Committee 215, Aeronautical Mobile Satellite (Route) Services, Next Generation Satellite Services and Equipment.