77-21-01
 ALL  ú ú N01 Page 408 ú Oct 10/97
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
EXHAUST GAS TEMPERATURE (TT4.95) THERMOCOUPLE PROBE - INSPECTION/CHECK
______________________________________________________________________
 1.  General
________
 A.  This procedure includes two tasks. One task is an inspection of the exhaust gas temperature (EGT) (TT4.95) thermocouple probe. The other task is a continuity and insulation resistance check of the EGT probe.
 B.  There are four EGT probes installed on the turbine exhaust case.
 C.  The EGT probes are installed (one each) at the 1, 4, 7, and 10 o'clock positions.
 D.  You must open the applicable core cowl panel to get access to the EGT probes.
 TASK 77-21-01-206-001-N00
 2.  Visually Examine the EGT Probe (Fig. 601)
______________________________
 A.  References
 (1)  
AMM 71-11-06/201, Core Cowl Panels

 (2)  
AMM 77-21-01/401, Exhaust Gas Temperature (TT4.95) Thermocouple Probe

 (3)  
IPC 77-21-01, Fig. 5

 (4)  
IPC 77-21-03, Fig. 1

 B.  
Access

 (1)  
Location Zone 412 Engine 1 - Turbine Exhaust Case 1, 4, 7, or 10 o'clock 422 Engine 2 - Turbine Exhaust Case 1, 4, 7, or 10 o'clock 432 Engine 3 - Turbine Exhaust Case 1, 4, 7, or 10 o'clock 442 Engine 4 - Turbine Exhaust Case 1, 4, 7, or 10 o'clock

 (2)  
Access Panel
 417 Left Core Cowl Panel - Engine 1
 418 Right Core Cowl Panel - Engine 1
 427 Left Core Cowl Panel - Engine 2
 428 Right Core Cowl Panel - Engine 2
 437 Left Core Cowl Panel - Engine 3
 438 Right Core Cowl Panel - Engine 3
 447 Left Core Cowl Panel - Engine 4
 448 Right Core Cowl Panel - Engine 4

 C.  
Procedure

 S 866-019-N00
 (1)  For the applicable engine, open these circuit breakers on the main power distribution panel, P6, and install the DO-NOT-CLOSE tags:
 (a)  
6G15 SCU ALT PWR ENG 1

 (b)  
6G23 ENG SCU 1

 (c)  
6G16 SCU ALT PWR ENG 2

 (d)  
6G24 ENG SCU 2

 (e)  
6G17 SCU ALT PWR ENG 3

 (f)  
6G25 ENG SCU 3

 (g)  
6G18 SCU ALT PWR ENG 4

 (h)  
6G26 ENG SCU 4

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 ALL  ú ú N02 Page 601 ú Jun 18/99
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
////////////////////////A / PW4000 SERIES /747-400 / ENGINES /MAINTENANCE MANUAL ////////////////////////
FLANGE P FLANGE P
FLANGE S
FLANGE S
FLANGE T FLANGE T
EGT (TT4.95) THERMOCOUPLE PROBE (4 LOCATIONS) SEEC DSEE A
CD SEE
SEE B TURBINE EXHAUST CASE
TURBINE EXHAUST CASE
SEEC D
NUT-ALUMEL STUD
(2 LOCATIONS)

WASHER (2 LOCATIONS) SEEC D
NUT-CHROMEL STUD (2 LOCATIONS)
WASHER A FWD B FWD(2 LOCATIONS)
HARNESS
LEADS
BRACKET
BOLT  EGT (TT4.95)
(2 LOCATIONS)  THERMOCOUPLE PROBE STUD (4 LOCATIONS)
EGT (TT4.95) THERMOCOUPLE
PROBE (EXAMPLE)

C
Exhaust Gas Temperature (TT4.95) Thermocouple Probe Inspection
Figure 601 (Sheet 1)

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 77-21-01
 ALL  ú ú N01 Page 602 ú Oct 10/92
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
SEE
3  L-A2423

CIRCUIT A DIAGRAM  CIRCUIT B DIAGRAM

Exhaust Gas Temperature (TT4.95) Thermocouple Probe Inspection
Figure 601 (Sheet 2)

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 77-21-01
 ALL  ú ú N01 Page 603 ú Oct 10/90
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