MIL-F-18372(Aer)
3.1.1.5 Acceleration Effect - Acceleration forces acting upon the control system's components shall
not result in forces at the pilot's control unless such forces are determined to be necessary and/or
desirable for the purpose of improving the handling qualities of the aircraft.
3.1.1.5.1 Effect of Acceleration on Type II and Type III Systems - Acceleration forces acting upon
hydraulic, pneumatic or electro-mechanical system components shall not affect the functioning of the
normal or emergency systems. Consideration shall be given to the fluid column used in hydraulic
systems.
3.1.1.6 Vulnerability - Consideration shall be given to the spacing and arrangement of the flight
control systems to reduce the vulnerability of the systems to the minimum value practicable. Also,
advantage shall be taken, wherever possible, of the shielding afforded by heavy structural members or
existing armor plate installation for the protection of the control systems, particularly in places
such as points of cable convergence, horns, bellcranks, main sheaves and walking beams.
3.1.1.7 Fouling Prevention - All elements of the control system, subject to fouling by loose gear,
shall be suitably protected or covered. Consideration shall be given to the protection of control
elements subject to fouling due to ice formation.
3.1.1.8 Clearances - All moving parts of a control system shall have sufficient clearance with each
other and with other parts of the aircraft to prevent fouling under all operating conditions. Con-
sideration shall be given to the effect of tolerances in manufacture, assembly, installation, rigging,
normal wear and normal deflection.
3.1.1.9 Temperature - Flight control systems shall be designed for operation at temperatures between
160°F (+71°C) and -65°F (54°C). However, if it is anticipated that these temperature limits will be
exceeded, components for the control system shall be selected or designed to operate at the anticipated
temperature.
3.1.1.10 Accessibility - All parts of the flight control systems shall be readily
accessible for
inspection, repair, adjustment of linkages and components, and for lubrication.
Inspection doors
shall be provided at pulleys, quadrants, connections and components, not otherwise
readily accessible.
It shall be possible to inspect the entire length of cables and push-pull rods for
corrosion and signs
of wear periodically without disconnecting the systems.
3.1.1.11 Drainage - Adequate provisions shall be made to drain control system components subject to
accumulation of moisture.
3.1.1.12 Bearings
3.1.1.12.1 Anti-Friction - Approved type, AN airframe, ball bearings shall be used throughout the flight
control system, except as indicated below. In the event design limitations do not permit the use of
ball bearings, prelubricated shielded roller or needle bearings may be used. Were roller or needle
bearings are used, consideration shall be given relubrication provisions. The inner race of the
bearing shall be clamped to prevent rotation of the Inner race with respect to the pivot bolt. Bearing
installations shall be arranged in such a manner that failure of the rollers or balls will not result
in a complete separation of the control. Direct axial application of control forces to a bearing shall
be avoided if possible. In the went such an arrangement is necessary, a fail safe feature shall be
provided.
3.1.1.12.2 Spherical Bearings -Where design limitations preclude the use of anti-friction bearings,
spherical type plain bearings approved by the Bureau of Aeronautics may be used. When used, spherical
type bearings shall have adequate provisions for relubrication.
3.1.1.12.3 Journal - Plain type journal bearings shall be avoided. However, where substantiated, and
where play and friction are not major considerations, journal or plain bearings, with adequate and
accessible provisions for lubrication, may be used.
3.1.1.12.4 Sintered - Sintered type or oil impregnated bearings shall not be used in those part of the
flight control systems which have slow moving or oscillating motions. Fast moving rotating application
such as in qualified motors and actuators are considered satisfactory.
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