PS Magazine - AUGUST 1977
PS, The Preventative Maintenance Monthly
ISSUE 297
AUGUST 1977
,
GIVE INVERTERS
ATTENTION
tHEY DESERVE
All
.
rotary
inverters are now a condition item± So,Lookfor
²
achange to
T
55-
1500±307±24
removing them from the histoRical iNfo requirement list± Data
Won't be colleCted so there is no time-Between³overhaul or retirement intErval±
The
idea is to keep the inverte´s
humming until they no longer pass
iNspectioN±
About every
200
flight hours (when
your bird is down For maintµnance)
give
the
inverter
the
¶ig
·ook±
Individual bird pubs are being up¸
dated± ¹lean andºnspe»t the inverte¼
for cracked or damaged cases, proper
bonding, security of mounting, and
broken connector pins
or
cracked
connector ins½rts±
46
t
m
±
·
²
'²"³´µ¶·¸ .¹º»¼ ½¾
¿
-
_
f
,\
¾yeball the brushes
for wear, one at a time sO they're put back in the same
place±
¿o indicÀte maximum wear, the brushes have a 1H2Áin wide wear mark
(groove) at about half the original brush length± IN soMe brushes the mark is a
ÂiagonÃl groove Än the bottom width of the brush± In others, the mark is a
parallel groove in the top edge of the brush± Åear to the end of the mark will
give you at least
500
operatioNal hours at full load± ¶ut when the brushes are
worn down to any part of the wear
mark, take the inverter ouÆ of the bird
and turn it in to suPport for neÇ
È
brushes±
ÉÊcusËin on the brush contact area
Ìf the commutator and slip rings aNd
loÍk For serious grooving or pitting±
Also, check for excessive vibration,
noise aNd ovÎrÏÐating±
EYeBALl
BrUsheÀ
Á
ÂÃÄ
WÅaÆ
Ç
MÈÆK
Inspection is not complete, mechs, without an operÑtional chÒÓk± Åatch the
output voltage and frequency under "no loadÔ aNÕ "Öll load,× as explained in
your aircrØftÙs pubÚ
If the invert½r wÛnÙt Üut ouÝÞ Ýurn it iß tÛ Your suÜport àr repair±
áoU make Ýhe decisioß ÝÛ Ýurn iâ that ißverter for reÜairÚ ãtäs åour jædgemeNt
callç
47
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