DOC AIRBUS | AMM A320FTEMPERATURE - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
1. General
The engine Exhaust Gas Temperature (EGT) is sensed and averaged by 9 thermocouple probes (chromel/alumel). They are installed through one specific nozzle segment of the stage 2 nozzle assembly located in the Low Pressure Turbine (LPT) case.
The engine Exhaust Gas Temperature (EGT) is sensed and averaged by 9 thermocouple probes (chromel/alumel). They are installed through one specific nozzle segment of the stage 2 nozzle assembly located in the Low Pressure Turbine (LPT) case.
T495 Thermocouple Wiring HarnessA. The T495 thermocouple wiring harness consists of:
- Three identical and interchangeable thermocouple lead assemblies with two probes.
- One thermocouple lead assembly with three probes.
- One upper extension lead.
- One lower extension lead.
- One main junction box assembly.
B. Description
(1) Each segment of the two-probe lead assembly has:
- Two rigid metal tubes (Con-o-clad), each equipped at one end with a thermocouple probe and an integral flange for attachment to a related boss on the LPT case.
- A junction box at the other end of the rigid metal tubes with a receptable for the connection to the main junction box assembly (for two of the three lead assemblies) and to the lower lead assembly (for the third one). The junction box has a flange for attachment to the LPT mounting flange S.
(2) Each segment of the three-probe lead thermocouple assembly consists of the items which follow:
(a) Three rigid metal tubes, each equipped with one thermocouple probe at one end and an integral flange for attachment to a related boss on the LPT case.
(b) A junction box at the other end of each rigid metal tube with a receptacle connector for connection to the upper extension lead and a flange for attachment to the LPT mounting flange S.
(3) The upper extension lead has:
- One rigid metal tube (Con-o-clad), equipped at each end with a mobile elbow-connector for connection to the main junction box assembly, and one of the three two probe thermocouple lead assemblies.
(4) The lower extension lead has:
- One rigid metal tube (Con-o-clad), equipped at each end with a mobile elbow-connector for connection to the main junction box assembly, and to the three-probe thermocouple lead assembly.
(5) The main junction box assembly has:
- Two rigid metal tubes (Con-o-clad), each equipped at one end with a mobile elbow-connector to the related two-probe lead assembly, and at the other end to a junction box. The junction box is equipped with two receptacles connectors for connection to the extension leads and one interface receptacle connector.
C. The electromotive force is averaged first in each of the individual lead assembly (2 probes and 3 probes), then in the main junction box assembly at the level of the interface connector.
The resultant averaged electromotive force is then sent to the ECU through the CJ13 harness and the HJ13 harness.
The resultant averaged electromotive force is then sent to the ECU through the CJ13 harness and the HJ13 harness.
2. EGT indication
The EGT indication appears on the upper display unit of the ECAM system.
The ECAM provides the EGT indication :
The index is displayed in amber above 915 deg. C (or above 725 deg. C during start sequence).
The index and the numerical value become red above 950 deg. C, the MASTER CAUT light comes on accompanied by the single chime, the following messages appear on the ECAM :
- ENG 1(2) EGT OVERLIMIT
- THR LEVER 1(2)...BELOW LIMIT
The ECAM warning is triggered if the indicated EGT is greater than 950 deg.C during take-off, and greater than 915°C during climb or cruise.
If the EGT has exceeded 950 deg. C:
The EGT indication appears on the upper display unit of the ECAM system.
The ECAM provides the EGT indication :
- in analog form thru a pointer which deflects in front of a dial,
- in digital form, in the lower section of the dial.
The index is displayed in amber above 915 deg. C (or above 725 deg. C during start sequence).
The index and the numerical value become red above 950 deg. C, the MASTER CAUT light comes on accompanied by the single chime, the following messages appear on the ECAM :
- ENG 1(2) EGT OVERLIMIT
- THR LEVER 1(2)...BELOW LIMIT
The ECAM warning is triggered if the indicated EGT is greater than 950 deg.C during take-off, and greater than 915°C during climb or cruise.
If the EGT has exceeded 950 deg. C:
- the maximum value reached is memorized,
- a small red line remains positioned on the analog scale, at that value (max pointer). The red line will disappear after a new take off or maintenance action through the MCDU.
Above 970 deg. C the messages displayed on the ECAM become:
- ENG 1(2) EGT OVERLIMIT
- THR LEVER 1(2)...IDLE
- ENG MASTER 1(2)...OFF