Air Conditioning: Air Distribution System

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FAA Aviation Safety SPECIAL AIRWORTHINESS INFORMATION BULLETIN SAIB: NM-13-02 SUBJ: Air Conditioning: Air Distribution System Date: October 22, 2012 This is information only. Recommendations aren’t mandatory.

Introduction This Special Airworthiness Information Bulletin advises registered owners and operators of certain The Boeing Company Model 747-8F series airplanes of an airworthiness concern regarding improper installation of riser duct and manifold assemblies of the air distribution system. Background Operators have reported findings of improper installation or incorrect manufacture of the riser duct and riser manifold assemblies of the main deck air distribution system. Leaks in these assemblies can occur if they are not correctly manufactured, installed or secured. While performing an A-check inspection on a Model 747-8F airplane, an operator found that all six main deck riser ducts were separated at the base of the risers or had some damage to the riser boot. Two of those riser ducts were completely separated allowing the free flow of air from the riser ducts, which can reduce air flow to the cabin. Additional Model 747-8F airplanes were identified as having a similar problem. Boeing has issued Special Attention Service Bulletin 747-21-2541, dated August 27, 2012, to provide operators with guidelines for inspecting the riser duct assemblies and riser manifold assemblies to ensure the ducts are manufactured and installed correctly, and applicable corrective actions. At this time, the airworthiness concern is not an unsafe condition that would warrant airworthiness directive (AD) action under Title 14 of the Code of Federal Aviation Regulations (14 CFR) part 39. Recommendations The FAA recommends that all owners and operators of the subject airplanes implement the actions outlined in Boeing Special Attention Service Bulletin 747-21-2541, dated August 27, 2012. For Further Information Contact Eric Brown, Aerospace Engineer, Cabin Safety and Environmental Systems Branch, ANM-150S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue SW, Renton, Washington 98057-3356; phone: (425) 917-6476; fax: (425) 917-6590; email: [email protected]. For Related Service Information Contact Boeing Commercial Airplanes, Attention: Data & Services Management, P.O. Box 3707, MC 2H-65, Seattle, Washington 98124-2207; telephone 206-544-5000, extension 1; fax 206-766-5680; Internet https://www.myboeingfleet.com.