This SAE Aerospace Information Report (AIR) describes the performance of platings and coatings for landing gear that potentially provide environmental compliance benefits versus the current baseline processes. The hazardous systems addressed in this version of the document include cadmium plating@ chromated primers@ and high VOC (volatile organic compounds) topcoats. Available data are presented for various standard tests in order to compare the replacement candidates. Conclusions are made as to the best performer(s) for each test section presented. These conclusions are not to be regarded as recommendations for or against any of the candidates. The AIR applies to landing gear structures and mechanisms for all types of civil and military aircraft. The potential replacements apply to both original equipment manufacturer (OEM) hardware and overhaul of in-service landing gears. Background This document addresses a number of materials and processes used in landing gear manufacturing and overhaul including cadmium@ chromium@ and volatile organic compounds (VOC). In the United States@ these substances are controlled in three primary areas: (1) the Occupational Safety and Health Administration (OSHA) oversees exposure in the workplace@ (2) the Environmental Protection Agency (EPA) oversees airborne emissions via the Clean Air Act@ and (3) the EPA also oversees waterborne effluent via the Clean Water Act. Cadmium is widely used as a sacrificial coating for corrosion protection of steel alloys. However@ cadmium is easily removed during paint stripping operations@ resulting in contamination of stripping media and large volumes of hazardous waste. Because low embrittlement cadmium is a soft@ easily removable coating@ it contaminates virtually everything it physically contacts (e.g.@ wiping rags@ hydraulic oil@ masking materials). The 1992 OSHA Expanded Standard for Cadmium established a permissible exposure limit (PEL) of 5 ?g/m3 and reduced the Action Level (AL) to 2.5 ?g/m3. This standard went into effect in 1996 and put nearly all overhaul operations at risk of violating AL and/or PEL@ requiring the use of continually more stringent overhaul process control@ worker medical surveillance and record keeping. Cadmium levels in effluent are regulated by the Clean Water Act@ but the needs and capabilities of the local waste water treatment authority require their involvement in establishing individual discharge standards. The European Union (EU) has already banned the use of cadmium for various applications but exempted flight safety critical parts. European airlines expect the exemption to be phased out and are requesting (a) harmonization of maintenance procedures and processes in which cadmium is involved@ (b) a policy commitment to replace cadmium for aircraft@ engines and components and c) consensus on selection of cadmium alternatives. Hexavalent chromium is a corrosion inhibitor used in chromated conversion coatings and chromated primers. Hexavalent chromium is a known carcinogen and a suspected human mutagen. It is the most dangerous form of chromium compounds. Once in metallic form@ such as hard chrome plate@ chromium is not considered a significant environmental problem. Other forms of chromium: metallic as in plated hard chrome@ or as an ingredient in corrosion-resistant steels; trivalent@ as in trivalent chrome conversion coatings or solutions@ are not considered a significant health@ safety@ or environmental problem. The new OSHA Cr6+ PEL (permissible exposure limit) issued on February 28@ 2006 lowers the upper limit for exposure of workers to hexavalent chromium (as Cr) to 5 ?g m-3 from its previous 52 ?g m-3@ measured as 8-h time-weighted averages. This drastic reduction affects any industrial process that could generate Cr6+ air emissions@ including hard chrome plating@ chromic acid anodizing@ priming and painting@ chromate conversion@ welding@ and rework of materials containing chromium. The limit applies to all forms of Cr6+@ including chromium trioxide@ chromic acid and chromates. In addition to reducing the PEL for Cr6+@ the new OSHA rule places a number of burdens on employers@ who are now required to: ? Monitor employee exposure to Cr6+ ? Establish separate regulated areas when Cr6+ levels are expected to exceed the PEL ?Provide respirators for workers exposed above the PEL Provide other PPE (personal protective equipment) as necessary for eye and skin protection@ together with change rooms and wash facilities ? Institute housekeeping activities to control spills and releases of Cr6+ ? Provide medical surveillance for employees who are exposed above the PEL@ show signs or symptoms of Cr6+ exposure@ or are exposed in an emergency ? Train workers about Cr6+ hazards@ and use signs and labels to communicate the hazards ? Keep records of exposure@ surveillance and training. The PEL action level@ which is the threshold that determines when ongoing monitoring is necessary@ is 50% of the PEL or 2.5 ?g m-3. However@ if Cr6+ concentrations are shown to be <0.5 ?g m-3 under all expected conditions@ then the OSHA rule does not apply at all. The Environmental Protection Agency (EPA) has finalized a National Emission Standard for Hazardous Air Pollutants (NESHAP) that includes coating operations at aerospace manufacturing and rework facilities. The standard requires existing and new major sources to control emissions to the level achievable by the Maximum Achievable Control Technology (MACT) consistent with section 112(d) of the Clean Air Act. The Hazardous Air Pollutants (HAPs) covered by this final rule include chromium@ cadmium@ methylene chloride@ toluene@ xylene@ methyl ethyl ketone@ ethylene glycol and glycol ethers. For existing sources@ the requirements of this rule became effective September 1998. The NESHAP limits on VOC are 420 g/L for topcoats and 350 g/L for primers.