Specifications

MIL-STD-i472i2
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5.9.10.5.1 High-torcwe fasteners. External hex or external double-hex wrenching elements
shall be provided on all machine screws, bolts or other fasteners requiring more than 14N~m
(10 lbfeft) of torque. When external wrenching fasteners cannot meet the mechanical fimction or
pemonnel safety mydrwnents, or in limited access situations, and where use is protected from
accumulation of foreign material, internal wrenching fasteners maybe used. Direct tool auxss
shall be
provided to allow for torquing without the use of imegular extensions.
5.9,10.5.2 Low-torauc fasteners. External-hex wrenching head, internal-hex wrenching head,
combination head (internal-hex or straight recess and external-hex wrenching head), or Torq-set
fasteners, should be provided where less than 14 N*m (10 Ibf*fOtorque is required. Intemal-
wrenching fasteners shall be provided only where a straight, or convex, smooth surface is requinxi for
mechanical function or personnel safety, and where use is protected from mmulation of foreign
material (e.g., ice, snow). Straight-slot or cross-recess type internal grip fasteners shall not be
provided, except as wod fasteners or where these type fasteners are provided on standard commemial
items,
5.9.10.5.3 Common fasteners. Whenever possible, identical screw and bolt heads shall be
provided to allow panels and components to be removed with one tool. Combination bolt heads such
as slotted hex head should be selected whenever feasible. Mentical fasteners shaUnot be used where
removal of wrong fastener can result in equipment damage or change to calibration settings.
5.9.10.6 Accessibility. The heads of mounting bolts and fasteners should be located on
surfaces readily accessible to the maintainer. Both hand and tool access shd be provided to the
unthreaded or loosened fastener.
5.9.10.7 Number of turns. Fasteners for mounting assemblies and subassemblies shall require
a minimum number of turns, compatible with stress, alignmen~ positioning, and load considerations.
When machine screws or bolts are nxy.Aired,the number of turns and the amount of torque shall be no
more than necessary to provide the required strength except when a common fastener is ut.iked. All
items requiring removal for daily or mom frequently scheduled inspections and servicing shall use
quick release fasteners.
5.9.10.8 Toruue Melin.. W&m fastener torquing to meet EMURFIshielding, thermal
conductance or other wmtmints is required for orgtiona.1 or hermediate level maintenance
actions, an instructional label or placard should be provided near the fasteners. Such labels shall
comply with requirements of 5.5 and speci~ required torque value and torquing squence.
5.9.11 &i.ittilun for efficient handling.
5.9.11.1 Rests and stands. When required for maintmmnce twiks,reata orstancisshouldbe
provided for placing units, test equiprnen&took, technical orders, and manuals. When permitted by
design requirements
, such M or stands shall be part of the basic unit, rac~ or console chassis.
5.9.11.2 Extension& Extensions and comected appurtenances, accessories, utiities, cables,
wave guides, hoses, and similar items shall not interfere with removing, repkacing,or carrying an
item. If such extensions and connected appurtenances interfere with these tasks, they shall be easily
mmOvedor&WWUK@d
km& quipmcni bcftxc h.andIing. Easy disconnect shall consis~of hand
qwratt]e quick disconnect Or standard hand mol operable disconnects in that order of
preference.
5.9.11.3 Wemht.
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