Figure 2-3. Thermocouple and Harness Check Setup.
compared. Refer to figure 2-4 and proceed as
(1) Turn FUNCTION SELECT, STD DAY,
and MASTER POWER switches to OFF position.
(2) Connect BH485 instrument cable to
INSTRUMENT CABLE receptacle on tester and to
egt indicator check adapter. Connect BH822 egt
indicator check adapter to proper terminal posts on
INDICATOR CHECK switch in proper resistance
position (see indicator for circuit resistance value).
If indicator is left in instrument
p a n e l , o n e a i r c r a f t l e a d m u s t be
disconnected If indicator is removed
f r o m i n s t r u m e n t p a n e l , a m o re
accurate check will be accomplished if
indicator is kept in normal operating
(3) Turn FUNCTION SELECT switch to A/C
IND CHECK position, TEMPERATURE switch to
OPERATE position, and MASTER POWER switch
to ON position.
(4) Observe reading on tester TEMP indicator
a n d a d j u s t A / C I N D A D J c o n t r o l t o t e st
temperature reading (usually 600 °C).
(5) The difference in the indication of the
tester TEMP indicator and the aircraft indicator is
the error of the aircraft indicator and should not
exceed allowable technical manual tolerance.
(6) If aircraft indicator exceeds technical
manual tolerance, repair or replace indicator.
(7) If indicator is within tolerance, proceed to
check resistance in paragraph d.
(8) Turn FUNCTION SELECT and MASTER
POWER switches to OFF position before removing
cables from tester and aircraft indicator.
c . N u l l - B a l a n c e T e m p e r a t u r e I n d i c a t or
Check. Connect the tester to the indicator at the
engine disconnect or at the indicator using the
appropriate adapter as shown in figure 2-5 and
proceed as follows:
(1) Turn FUNCTION SELECT switch to A/C
I N D C H K p o s i t i o n, R E S I S T A N C E & A / C
INDICATOR CHECK switch to NULL BAL
position, TEMPERATURE switch to OPERATE