MIL-F-18372(Aer)
3.1.1.12.5 Self-Alignment - Self aligning bearings shall be used wherever necessary to eliminate the
possibility of binding or excessive wear due to misalignment of connecting parts.
3.1.1.13 Horms and Brackets - All horns and brackets shall be designed and attached so that they
can be readily replaced in service.
3.1.1.14 Shock Absorber Cords - Shock absorber cords shall not be used in flight control systems.
3.1.1.15 Chains - Chains shall not be used in flight control systems.
3.1.1.16 Fastenings - In general, fastenings shall be in accordance with SD-24 with the following
amplifications: Clevis pins shall not be used. Clevis bolts with shear castle nuts and cotter pins
are considered satisfactory in shear applications. Self locking type nuts shall not be used at single
attachments or where loss of the bolt would affect safety of flight. Bolts mounted upside down in
single attachments shall have the head lockwired to prevent loss of bolt in the event the nut is loose.
Bolts less than ¼ dia. shall not be used in any single attachment in the primary flight control systems
or in any application on all flight controls or associated systems where loss of a bolt would affect
the safety of the flight control systems. Provisions shall be made to prevent jamming, bending or
failure of the components in the flight control systems due to possible excessive over-torque being
applied to the attaching bolts and nuts. Written or printed warnings in the service handbooks, drawings,
placards, etc., to prevent bolts from being over-torqued are not considered provisions to meet this
requirement.
3.1.1.17 Cable Systems
3.1.1.17.1 Cables - Control cables shall conform to the applicable specifications. Carbon steel
cable shall be used except where corrosion factors preclude the use of the carbon steel cable in which
case, corrosion-resistant steel cable shall be used.
3.1.1.17.2 Kinematics - The kinematics of the components in the cable systems shall be such as to
prevent an objectionable amount of change in cable tension throughout their flight and ground operational
range.
3.1.1.17.3 Tension of Cable Systems - Wherever necessary, provisions shall be made to prevent
excessive variation of cable tensions due to temperature changes. Consideration shall be given to the
effect of heat from local areas such as engine nacelles, cabins, heat deicers, etc., which may cause
temperature rises in an adjacent portion of a control system while the aircraft structure proper remains
at the ambient air temperature.
In the interest of reducing control system friction, initial tensions should be held to the lowest
practicable values that provide safe and satisfactory operation considering probable application of
limit loads to the system and the effect of temperature changes.
3.1.1.17.4 Attachments - Terminals, disconnect fittings, turnbuckles, etc., shall be provided as
necessary to facilitate rigging and maintenance of the control system.
3.1.1.17.5 Location of Attachments - Gable attachments shall be located in such a manner that it is
impossible to cross connect cables during installation. Cable attachments shall be located in such a
manner that it is impossible for them to jam or hang up on adjoining structure or other fittings.
3.1.1.17.6 Terminals - Terminals shall be of the swaged type and shall conform to the applicable
specifications. Ball type swaged terminals shall not be used in primary control systems except for
attaching cables to quadrants where standard fork and eye fittings are not adaptable. Ball type swaged
terminals shall not be used with strap fitting as a substitute for standard fork and eye fittings. All
cable assemblies fabricated with swaged terminals, sha ll be proof-loaded, in accordance with the appli-
cable specification.
3.1.1.17.7 Cable Turn Radius - The ratio of sheave (pulleys, drums, sectors, etc.,) diameter to cable
diameter shall not be less than the following values: (where the cable load iS the maximum load expected
in the cable under normal operating conditions.)
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