Marvel 7HEL078N1 User manual

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40#North#2nd#Street#
Stroudsburg,#PA#18360#USA#
570<421<6221#

!!!!!!!!!!!!!!!!!!!!!!!!!!!The$Marvel$Manufacturing$Company$copyright$2017!
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Tail#Rotor#Balance#
Eurocopter#Models#BO#105,#BK#117,#EC#145#Typical
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Balance#Equipment#
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#1#ea# 7HEL078N1### # Kit#–#Tail#Rotor#Balance#
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Note:# The#7HEL078N1#Kit<Tail#Rotor#Balance#supplies#all#balance#
equipment#items#required#for#this#rotor#and#includes#Part#Number#
3165#Arbor#Assembly<Balance#Indicating.#
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The#7HEL077N1#Kit<Tail#Rotor#Balance#Adapter#is#recommended#for#
use#by#those#already#in#possession#of#Part#Number#3165#Arbor#
Assembly.#
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Description#
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The#subject#Tail#Rotor#is#balanced#as#a#hub#and#blade#assembly,#excluding#the#
pitch#control#linkage#and#teeter#bolt.#
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The#3165#Balance#Indicator#Arbor#is#used#with#accessory#adaptering#to#mount#the#
rotor#in#a#fixed#position#below#its#lower#end.#A#backbalance#weight#and#
supporting#anchor#ring#are#used#to#raise#the#center#of#gravity#of#the#total#
suspended#load#to#a#position#on#the#arbor#that#will#provide#the#desired#balance#
indication#sensitivity.##
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The#rotor#hub#is#secured#to#the#fork#section#of#the#adapter#with#pins#inserted#
through#each#fork,#engaging#the#hub#and#blade#interconnecting#fitting#bores.#
Linkage#attachment#bolts#of#the#pitch#arms#contact#the#outer#end#of#the#pins#for#
blade#pitch#positioning.#A#threaded#pressure#ring,#located#central#in#the#adapter#
fork#removes#rotor#teeter#and#positions#its#span#axis#square#with#the#normal#axis#
of#rotation.#
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Balance#Procedure#
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1.# Depress#indicator#Collar#of#3165#Balance#Indicator#Arbor,#releasing#oil#seal,#
and#reposition#to#provide#minimum#free#clearance#with#arbor#end.#Lightly#
secure#with#set#screw.##Suspend#from#hoist#or#other#support.#

!!!!!!!!!!!!!!!!!!!!!!!!!!!The$Marvel$Manufacturing$Company$copyright$2017!
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2.# Install#3262#Weight#on#arbor#from#lower#end#and#position#top#surface#at#the#
9#7/8”#inch#Arbor#Scale#location.#Secure#by#moderately#tightening#the#two#
set#screws#evenly.###
3.# Install#3260#Ring#on#Arbor#and#position#against#underside#of#weight.#
Moderately#tighten#its#set#screws#evenly.#
4.# Position#Rotor#Assembly#with#static#stop#sections#of#hub#downward#on#
suitable#support#and#visually#align#bores#of#blade#interconnecting#fitting#
and#hub.#
5.# Screw#threaded#ring#of#3255#Adapter#to#stop#against#the#yoke#body#and#
install#Adapter#to#Rotor#with#3172#Pins#(2)#inserted#through#bores#of#yoke#
fork#into#rotor#hub.#Install#pins#full#depth#to#set#on#top#of#pin.##Position#
blade#pitch#as#necessary#during#operation#to#provide#clearance#and#
position#linkage#bolt#of#pitch#arm#above#extension#section#of#3172#Pins.#A#
length#of#.187”#diameter#rod#approximately#4”#long#inserted#in#the#outboard#
bore#of#the#3172#Pin#will#assist#installation#and#removal.#
6.# Screw#threaded#ring#section#of#3255#Adapter#downward#to#press#against#
rotor#hub#to#remove#teeter#action.#
7.# Install#the#assembled#group#on#lower#end#of#arbor,#seating#on#internal#stop#
ring.##Secure#by#moderately#tightening#the#two#adapter#set#screws#evenly.#
8.# Loosen#threaded#ring#of#3255#Adapter#from#contact#with#rotor#hub#and#
centralize#rotor#to#obtain#equal#space#between#bushings#in#rotor#hub#and#
adapter#fork.#Use#feeler#gage#or#dial#indicator.##Maintain#seated#position#of#
3172#Pins.#
9.# Retighten#threaded#ring#of#3255#Adapter#to#contact#rotor#hub.#Check#to#
insure#linkage#bolts#of#pitch#arms#are#seated#against#3172#Pin#extensions.#
10.#Stabilize#movements#of#the#suspended#assembly#and#observe#balance#
condition#as#indicated#by#exposure#of#black#disc#in#top#surface#of#arbor#
shaft.##Check#to#insure#indications#are#not#affected#by#interferences,#air#
drafts,#or#movements#of#nearby#personnel.#
11.#Refer#to#applicable#Helicopter#Maintenance#Manual#for#balance#tolerance,#
method#of#correction#or#other#assembly#requirements.#
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!!!!!!!!!!!!!!!!!!!!!!!!!!!The$Marvel$Manufacturing$Company$copyright$2017!
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