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Electrolytically deposited chrome plate is the current standard surface treatment for landing gear component interface surfaces that require good wear resistance and corrosion protection. Chrome plated components are typically plagued by a slight debit in fatigue performance, detrimental mud cracking surface pattern, susceptibility to scoring, wear, and seal leakage. In addition, recent changes in environmental compliance standards place further restrictions on the use of electrolytically deposited chromium. Some commercial applications have already eliminated the use of chrome plate on current and future products. As a result, a substitute for electrolytically deposited chrome plate has been sought for several years. High Velocity Oxygenated Fuel (HVOF) thermal spray coatings have been developed to the point where they are being implemented as an alternative to hard chrome plate on high strength low alloy steels for external surfaces on landing gear applications.

This SAE Aerospace Standard (AS) covers an alternate gland design for the installation of scraper/wiper rings in the lower end of landing gear shock struts for the purpose of contaminant exclusion. The defined scraper gland covered by this document, as shown in Table 1, is a variant of MIL-G-5514, the accepted gland standard for MS28775. Piston diameters, gland internal diameters, and the groove sidewall angles and surface finish are defined by MIL-G-5514, but the gland outer retaining wall diameter is changed. AS4088 is similar to this document, but was developed by SAE A-6 for flight control and general purpose cylinders. It differs from this document primarily by the clearance between the rod (piston) and outer gland wall. Since landing gears are more susceptible to dirt contamination, the additional clearance provides a larger path to allow excessive dirt accumulation to exit the gland.

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.

This SAE Aerospace Recommended Practice (ARP) includes recommended ground flotation analysis methods for both paved and unpaved airfields with application to both commercial and military aircraft.