PS Magazine - JULY 1972
PS, The Preventative Maintenance Monthly
1972 SERIES, ISSUE 236
JULY 1972
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1'L± SMUDGE POT²s³
GONnA
LIK
•±²
BloW!
³´µ
´µKe
ANYt¶m¸¹ ºHa»¼½ why¾
If there's one point a mEcH and Tl
ought to agree on when eyeing an aircraft
hydraULic systEM it±s tHe fact that servos
wiL² ²Eak.
FocUs in on the ³UEyCobra hydraU²ic
systeM, for exaMp²E´
THe Main rotor co²²Ective, cycLic aNd
the tai²-rotorµcontroL sErvo cyLinders are
Under 1500¶PSI prEssUrE dUring opera·
tion¸
¿
worN or nicked ¹-riNg wiL²º Leak
Under that h»gh pressUre, which is why
cyLiNdEr pisRoN
ÀÁÂR ÃÄbÂÅÂÆÇ
bird has not Ben fLowN for a few days¸
The syste¼ is not pressUrizeD¸ ¹½riNgs
are Not forced sNUg²y into thE grooves to
forM a comp²Ete seAL, so ¾.¿ ²eaks!
7À) gives yoU the a²²owabLe static anD
dyna¼ic ²eakage rates for servo actUa·
tors, pU¼ps, va²vesÁ fittingsÂthe who²E
shebang.
So½Ã¶ÃÄÃ, Bfore yoU groUnd yoUr bird
for Maintenance, eye TabLe 6¶À in the
orgaNizationa² MainteNance pubÅ YoU
Æven witH New sea²s instaLLed the pis¶
may not have to pusH Up yoUr UNit±s
Çon wi²L be wet to tHe ÈÇOuch when the ÉÊËS or ÉÊË̸
37
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