| 4.4.4.5-4-1 Ensure fastener design is evaluated |
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Ensure positive locking devices such as self-locking threads, bent tab washers, are utilized. Avoid use of locking methods that rely on preload or locking compounds. Avoid setscrews where possible. Avoid snap rings to retain pins in linkages, etc, where moment loads may be imposed on the snap ring. New snap rings should be used at each installation (no reuse). E clips should not be used on either flight or non-flight items where FOD control is required.
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NA
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NA
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AIAA S-114-2005
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| 4.4.4.5-4-2 Ensure design of retention and release devices is evaluated |
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Failure of primary release mode should not prevent operation of remaining redundant release modes. Ensure geometry, contact pressure, and lubrication are designed to preclude cold/friction welding, galling, and seizing. Recommend 25% pin diameter retraction margin (or flush with housing/clevis) for pin pullers under worst-case dimensional and environmental conditions. Ensure complete clampband or cable retraction below and away from separation flanges. Include provisions to avoid recontact with flanges. Recommend kick-off springs or other suitable devices have a stroke long enough to guarantee complete disengagement from retention mechanism.
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NA
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NA
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AIAA S-114-2005
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| 4.4.4.5-4-3 Ensure design of pivots and hinges is evaluated |
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Use redundant sliding surfaces for pivot pins. Split or rolled spring-action pins should not used as pivots.
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NA
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NA
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AIAA S-114-2005
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| 4.4.4.5-4-4 Ensure design of non-electrical cables is evaluated |
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Cables (non-electrical) should be adequately guided and supported. Ensure pulleys utilize pulley guards that extend to tangency points of cable.
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NA
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NA
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AIAA S-114-2005
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| 4.4.4.5-4-5 Ensure spring design and usage is evaluated |
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Ensure helical compression/tension springs are designed to possess max shear stress of 80% of allowable shear yield; similar margin against bending for other spring types such as torsion, leaf, constant torque/force, or disc (to reduce possibility of stress relaxation). Use redundant springs, capable of working independently, for critical applications.
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NA
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NA
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AIAA S-114-2005
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| 4.4.4.5-4-6 Ensure design of dampers is evaluated |
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Ensure adequate margin to input loads, including effects of deadband and backlash. Ensure single use (no reuse) of crushable material or plastic deformation of soft metals to absorb energy; these should be sized via development tests. Ensure viscous dampers are vacuum-filled to preclude entrapment of air. Recommend provisions for temperature-induced changes in fluid volume and viscosity to maintain required damping throughout temperature range.
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NA
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NA
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AIAA S-114-2005
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| 4.4.4.5-4-7 Ensure design of stops and latches is evaluated |
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Recommend 2.0 structural yield factor of safety, by static analysis, on stops. Latches should operate in the absence of deployable kinetic energy just before engagement.
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NA
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NA
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AIAA S-114-2005
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| 4.4.4.5-4-8 Ensure design of bearings is evaluated |
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Recommend minimum hardness of Rockwell C58. Bearing design should consider materials, stresses, stiffness, fatigue life, preload, and possible binding under normal and worst case combined loading conditions plus expected environmental conditions. Consider alignments, fits, tolerances, thermal- and load-induced distortions, etc., for determining preload variations. The mean Hertzian contact stress should not exceed values in AIAA-S-114-2005 when subjected to the yield load. Ensure bearings used in precision applications meet ABEC 7, 7P or 7T tolerances (or better). Upper and lower extremes of contact ellipses should be contained by raceways, or effects of truncation should be assessed.
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NA
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NA
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AIAA S-114-2005
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| 4.4.4.5-4-9 Ensure design of switches is evaluated |
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Ensure switch mounting and orientation are such that misadjustment of switch will not prevent full travel of deployable to its stop.
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NA
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NA
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AIAA S-114-2005
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| 4.4.4.5-4-10 Ensure usage of lubrication and material finishes is evaluated |
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Ensure sufficient lubricant amount and appropriate lubricant type are provided to support proper operation throughout the life cycle of all surfaces with relative motion. For sliding contact, ensure threshold galling stress is higher than expected max Hertzian contact stress . Ensure solid (dry) film lubricants are applied to surfaces by processes that provide a predictable, uniform, adherent, and repeatable lubricant film. Ensure hard coatings are applied by proven processes that assure coating will not flake off under max stress. Ensure loads are below bearing yield strength of substrate material.
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NA
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NA
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AIAA S-114-2005
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