31 July 2011 C1 CIVIL AVIATION DEPARTMENT HONG KONG ...

2 ApplicabilityThis Airworthiness Notice applies to all Hong Kong registered turbine powered largeaeroplanes certificated after 1 January 1958 in the Transport or Private Categorieswith a maximum type certificated passenger capacity of 30 seats or more, OR amaximum payload of 3,402 kg (7,500 lbs) or more.Note:Maximum payload equates to maximum design zero fuel weight minus operationalempty weight.3 RequirementHolders of TC and major modification approvals directly related to the fuel systeminstallation on applicable aircraft types are required to carry out a safety assessment inaccordance with the principles of JAR 25.1309, using the guidance material providedin the Interpretative Material (IM) to JAA Interim Policy INT/POL/25/12 (availableon internet via http:/www.jaa.nl/certification/fuel_tank_safety/fuel_tank_frame.htmlunder "D - Harmonised JAA-FAA Policy.pdf"). It must be shown that an ignitionsource within the fuel system cannot result from a single failure and is extremelyimprobable. For the purposes of this analysis, the whole fuel system should beassumed to be in the flammable range. In addition it should be shown that no heattransfer can lead to fuel auto-ignition within the fuel system. All systems, includingthe fuel system, that can release heat, in normal and failure conditions to the fuelsystem should be considered.Although the assumption is that the fuel tank will always be considered to beflammable, it is recognised that not all non-compliances with JAR 25.1309necessarily result in an unsafe condition. Harmonised criteria have been developedto determine those non-compliances which result in a potential unsafe condition thatrequires mandatory corrective action.These criteria, including assessment of the fuel tank flammability, are defined in theAttachment 3 to JAA Letter 04/00/02/07/02-L291 (available on internet viahttp:/www.jaa.nl/certification/fuel_tank_safety/fuel_tank_frame.html under "D -Harmonised JAA-FAA Policy.pdf").Operators are required to identify and list all aircraft fuel tank system majormodifications ∗ as installed on their aircraft. It is the responsibility of the operators tosatisfy themselves that the safety reviews required by this policy have been carriedout for all major modifications/Supplemental Type Certificates (STC) installed ontheir aircraft. In cases where the approval holder(s) is(are) unable to carry out thesafety review then the operator must engage the services of an appropriately approveddesign organisation to carry out the above safety review.The outcome of these review exercises is expected to be the identification ofmodifications to address unsafe conditions, additional Airworthiness Limitations, new∗ For the purpose of this Airworthiness Notice, "major modifications" includes "major repairs".30 September 2003 AN-55 P.2