PS Magazine - SEPTEMBER 1984
PS, The Preventative Maintenance Monthly
ISSUE 382
SEPTEMBER 1984
CH-47 Chinook .
.±
Beep-Beep! Check That Resistor
Checking minimum beep resistance on the CH-47A, B
±nd C's engine con²
dition control resistors c±n e±t up ± mech±nic's time ±nd P±tience to the m±x.
It's ± hit³or-miss jo´ testing ±nd ±djusting resist±nce. You h±ve to re±ch ´ehind
the TB 19 terminµl bo±rd to do the jo´. You c±n't see wh±t you're doing, in¶
cre±sing the ch±nces of connecting the
multimeter to the wrong termin±l.
There's ±n e±sier·±nd qUicker¸w±y
to do the job.
·
Remove the cover of the TB 19 ter¹
min±l bo±rd in the AC control
º
pod. To
check the No. 1 engine resistor, use ±n
AN/»SM-223 multimeter. Set it to
RXL. ¼ouch the probes to TB 19 ter½
min±ls 2 ±nd L inste±d of the resistor
R202 pins 2 ±nd 3. The meter should
re±d 50 ohms Fr the C¾¿47A or 25
ohms Fr the B ±nd C models. If not,
±djust thE resistor until it does.
Àor the No. 2 engine, touch the
probes to TB 19 termin±ls 9 ±nd 6 in½
ste±d of R200 resistor pins 2 ±nd 3. TÁe
meter should re±d 50 or 25 ohms
(depending on the models) here, too.
When you get the resistors ±djusted;
repl±ce the termin±l bo±rd cover.
54
SEP 8±
0
•
±
D
g
Pito± Ports
Giving You Static?
Âitot/sñtic ports ñke uP little sP±ce
on ±n ±ircr±ft. But ifthe port holes ±re
covered or the lines get cloGgÄd, they
c±n c±use big troubleÅlike ± 200¿ft erÆ
rorÇ in the ±ltimetÈr, ± Élse ±irspeed
re±ding or ± bÊm vertic±l velocity
re±douË.
Think wh±t would h±ppeÌ during
a
pinn±cle ±Ppro±ch under ±ny of those
h±ndic±Ps!
So m±ke sure to keep your bird's
pitot/sñtic Íports cle±n ±nd cle±r.
²
²
²
²
²
³
²
Âl±inly m±rk the Ports, ±ccording to
thÈ poop in TB 746-93¿2. Th±t w±y,
bird mechs won't P±int over the holes.
SeP 8±
55
Cle±n tÎe sñtic tubes like it s±ys in
p±r± 3³30L±(3) of TM 55³1500Ï204³
25ÐL. Then Fllow p±r±s 3-30L±(3) ±nd
(4) to test Fr le±ks.
When w±shing your ±ircr±ft, keep
w±ter out of the st±tic lines by coverÑ
ing the port holes. But don't stick
pressure³sensitive t±pe directly on the
Ports. Òhen you pull the t±pe oÓ, the
gummy sÃUÓ sñys behind, blocking the
holes ±nd ±ttr±cting dirtÔ
Inste±d, t±pe ± piece of thin Pl±stic
StatIc
pOrt
0
T²IN plastIc
over the hoÕe with dr±fting t±Pe, ÖSN
7510-00-198-5831. Remember to t±ke
it oÓ ±t the ×end of the w±sh job.
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