(2)
A resistance check of the thermocouple trim box.
B.
When a thermocouple trim box is replaced on the APU, the value of the exhaust gas temperature (EGT) trim box must be calibrated to the EGT value marked on the engine reference data plate. The location of the engine reference data plate is at the left side of the APU load gearbox and below the left APU mount bracket.
C.
The thermocouple trim box is on the bottom left aft side of the air inlet plenum.
TASK 49-61-04-825-011
2. Thermocouple Trim Box Calibration (Fig. 501)_________________________________
A. References
(1)
AMM 49-61-04/401, Thermocouple Trim Box
B.
Procedure
S 025-022
(1)
If the thermocouple trim box is installed on the APU, do this task: Thermocouple Trim Box Removal (AMM 49-61-04/401).
S 025-024
(2)
Remove the two screws (2) and cover (3) from the back of the thermocouple trim box (1).
(3)
Remove the gasket (4) from the thermocouple trim box (1).
S 825-026
(4)
Do these steps to calibrate the thermocouple trim box:
(a)
Identify the EGT TRIM value on the engine reference data plate.
(b)
Find the TRIM DEG value that agrees with the EGT TRIM value.
S 025-025
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MAINTENANCE MANUAL
SEE A FWD SEE C SEE B
APU COMPARTMENT
FWD
MOD. LEVEL SERIAL NO. A
H BALANCING DATA
REF. DATA AT 29.2 IN. HG.ABS. AT 37.8`C H AT MAX. ECS RATING `C `C LBS RPM EGT EGT TRIM DRY WEIGHT N2 IN DEGREES EGT TRIM VALUE CELSIUS 4. GASKET 1. THERMOCOUPLE TRIM BOX 3. COVER FWD
B ENGINE REFERENCE DATA PLATE 2. SCREW (2 LOCATIONS) C
Thermocouple Trim Box Calibration Figure 501 (Sheet 1)
L77168
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36 42 39 6 15 12 33 30 27 24 21 18 9 3 0 -3 -6 -9 -12 -15 -21.6 81.0 75.6 70.2 64.8 59.4 54.0 48.6 43.2 37.8 32.4 27.0 21.6 16.2 10.8 5.4 0 5.4 -10.8 -16.2 -54.0 -86.4 -27.0 -32.4 -37.8 -43.2 -48.6 -59.4 -64.8 -70.2 -75.6 -81.0 -18 -21 -24 -27 -30 -33 -36 -39 -42 -45 -48 -TRIM DEG `C`F 9 8 7 6 5 4 3 2 1 12 11 10 17 31 30 32 29 28 27 26 25 24 23 22 21 20 19 18 16 15 14 13 J11 PINS A AND C OHMS X 1000 RESISTANCE ACROSS X X X X X X X X X X X X X X X X X X X X X X X X X X X X XX X X X X X X X X X X X X X X X X XX X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X W1W2W3W4W5 JUMPER SELECTION ("X" DENOTES JUMPER REMOVED)
Thermocouple Trim Box Calibration
Figure 501 (Sheet 2)
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K29933
A
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(c)
Identify the jumper(s) that agree with the TRIM DEG value.
(d)
Cut the applicable jumper(s).
CAUTION: MAKE SURE THE JUMPER(S) THAT YOU CUT ARE REMOVED FROM THE
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