Engine 1 Pylon Loop B Inoperative

TASK 36-22-00-810-844-A
Engine 1 Pylon Loop B Inoperative

1. Possible Causes

wiring
BMC-2 [1HA2]
SENSING ELEMENT-OVHT, L PYLON LOOP B [101HF1]
CABLE-CONNECTING, L PYLON LOOP B [104HF1]
CABLE-CONNECTING, L PYLON LOOP B [102HF1]
SENSING ELEMENT-OVHT, L PYLON LOOP B [106HF1]
CABLE-CONNECTING, L PYLON LOOP B [103HF1]
CABLE-CONNECTING, L PYLON LOOP B [105HF1]

2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
9240SI	1	CONTROLLER-LOOP

B. Referenced Information

REFERENCE	DESIGNATION
TSM TASK 36-22-00-810-884-A	Leak Detection of the Engine 1 Pylon Loop B
ESPM 204422
AMM 36-11-00-740-802	BITE Test of the Engine Bleed Air System (EBAS) (System Test)
AMM 36-11-34-000-001	Removal of the BMC
AMM 36-11-34-400-001	Installation of the BMC
AMM 36-22-00-100-803	Clean the Overheat Detection System (OHDS) Connectors and Apply the Electrical Insulating Compound
ASM 362201
AWM 362202
AMM 36-22-15-000-802	Removal of the Pylon Overheat Sensing-Elements
AMM 36-22-15-000-803	Removal of the Pylon Overheat Sensing-Elements
AMM 36-22-15-400-802	Installation of the Pylon Overheat Sensing-Elements
AMM 36-22-15-400-803	Installation of the Pylon Overheat Sensing-Elements

3. Fault Confirmation
Subtask 36-22-00-740-060-A ** ON A/C NOT FOR ALL

A. Test
(1) Do the BITE test of the EBAS AMM 36-11-00-740-802.

4. Fault Isolation
Subtask 36-22-00-810-108-B ** ON A/C NOT FOR ALL

A. If the test gives the maintenance message ENG1 PYLON LOOP B INOP or ENG1 PYLON LOOP B OPEN:

NOTE: This procedure is applicable when there is a loss of the engine-1 pylon loop-B detection-signal or to the incorrect continuity of the loop.

Remove BMC-2 AMM 36-11-34-000-001.
On shelf 96VU, connect the 9240SI CONTROLLER-LOOP between BMC-2 pin AA/4E and AA/5E ASM 362201.
Do a check of the continuity resistance shown on the 9240SI CONTROLLER-LOOP:

(1) If the continuity resistance value is less than 8 Ohms:

On shelf 96VU, connect the 9240SI CONTROLLER-LOOP between connector BMC-2 pin AA/4E and the ground ASM 362201.
Do a check of the insulation resistance shown on the 9240SI CONTROLLER-LOOP.

(a) If the insulation resistance is more than 10 kOhms:

Go to Para. 4.B.

(b) If the insulation resistance is less than 10 kOhms:

Do the fault isolation steps (Ref. TSM TASK 36-22-00-810-884).

(2) If the continuity resistance value is more than 8 Ohms

Connect the 9240SI CONTROLLER-LOOP between connector 423VC pin A/2 to A/3 AWM 362202.

(a) If the continuity resistance value is more than 8 Ohms:

Do a visual inspection of the sensing elements and the connecting cables on engine 1 pylon loop B.

1 If a sensing element or a connecting cable is damaged:

Disconnect the 9240SI CONTROLLER-LOOP from 423VC connector pin A/2 to A/3.
Replace the defective sensing element or connecting cable AMM 36-22-15-000-802 and AMM 36-22-15-400-802, AMM 36-22-15-000-803 and AMM 36-22-15-400-803.
Install BMC-2 AMM 36-11-34-400-001.

2 If no sensing element or connecting cable is damaged:

Go to Para. 4.B.

(b) If the continuity resistance value is less than 8 Ohms:

Connect the 9240SI CONTROLLER-LOOP between connector 423VC pin A/2 and BMC-2 pin AA/4E AWM 362202.

1 If the continuity resistance value is more than 8 Ohms:

Disconnect the 9240SI CONTROLLER-LOOP from connector 423VC pin A/2 and BMC-2 pin AA/4E.
Repair or replace the wiring ESPM 204422.
Install BMC-2 AMM 36-11-34-400-001.

2 If the continuity resistance value is less than 8 Ohms:

Connect the 9240SI CONTROLLER-LOOP between connector 423VC pin A/3 and BMC-2 pin AA/5E AWM 362202.

a If the continuity resistance value is more than 8 Ohms:

Repair or replace the wiring ESPM 204422.
Install BMC-2 AMM 36-11-34-400-001.

b If the continuity resistance value is less than 8 Ohms:

Do the cleaning procedure AMM 36-22-00-100-803.
Do the BITE test of the EBAS AMM 36-11-00-740-802.
* If the fault continues:
** Replace BMC-2 [1HA2] AMM 36-11-34-000-001 and AMM 36-11-34-400-001.

Subtask 36-22-00-810-202-A ** ON A/C NOT FOR ALL

B. Dichotomy Procedure

NOTE: The purpose of this procedure is to find and isolate the element that causes a high continuity resistance on the on loop-B of the engine-1 pylon.

(1) Connect the 9240SI CONTROLLER-LOOP between connector 423VC pin A/2 to terminal block 450VT1 pin 6/A AWM 362202.
(2) Do a check of the continuity resistance shown on the 9240SI CONTROLLER-LOOP:
(a) If the continuity resistance value is more than 8 Ohms:

Disconnect the sensing element (101HF1) from connecting cables (102HF1) and (104HF1) AMM 36-22-15-000-803.
Measure the continuity resistance with the 9240SI CONTROLLER-LOOP between the center pin on the two ends of each of the sensing element.
Do a check of the continuity resistance shown on the 9240SI CONTROLLER-LOOP:

1 If the continuity resistance value is more than 8 Ohms:

Disconnect the 9240SI CONTROLLER-LOOP.
Replace the defective SENSING ELEMENT-OVHT, L PYLON LOOP B [101HF1] or CABLE-CONNECTING, L PYLON LOOP B [104HF1] or CABLE-CONNECTING, L PYLON LOOP B [102HF1] AMM 36-22-15-000-803 and AMM 36-22-15-400-803.
Install BMC-2 AMM 36-11-34-400-001.

2 If the continuity resistance value is less than 8 Ohms:

Disconnect the 9240SI CONTROLLER-LOOP.
Clean all the connections of sensing element (101HF1) and connecting cables (102HF1) and (104HF1) to remove contamination and decrease the resistance of the loop AMM 36-22-00-100-803 AWM 362202.
Install the sensing element (101HF1) AMM 36-22-15-400-803.
Install BMC-2 AMM 36-11-34-400-001.

(b) If the continuity resistance value is less than 8 Ohms:

Connect the 9240SI CONTROLLER-LOOP between connector 423VC pin A/3 to terminal block 450VT1 pin 6/B AWM 362202.
Do a check of the continuity resistance shown on the 9240SI CONTROLLER-LOOP:

1 If the continuity resistance value is more than 8 Ohms:

Disconnect the sensing element (106HF1) from connecting cables (103HF1) and (105HF1) AMM 36-22-15-000-802.
Measure the continuity resistance with the 9240SI CONTROLLER-LOOP between the center pin on the two ends of each of the sensing elements.
Do a check of the continuity resistance shown on the 9240SI CONTROLLER-LOOP:

a If the continuity resistance value is more than 8 Ohms:

Disconnect the 9240SI CONTROLLER-LOOP.
Replace the defective SENSING ELEMENT-OVHT, L PYLON LOOP B [106HF1] or CABLE-CONNECTING, L PYLON LOOP B [103HF1] or CABLE-CONNECTING, L PYLON LOOP B [105HF1] AMM 36-22-15-000-802 and AMM 36-22-15-400-802.
Install BMC-2 AMM 36-11-34-400-001.

b If the continuity resistance value is less than 8 Ohms:

Disconnect the 9240SI CONTROLLER-LOOP.
Clean all the connections of sensing element (106HF1) and connecting cables (103HF1) and (105HF1) to remove contamination and decrease the resistance of the loop AMM 36-22-00-100-803 AWM 362202.
Install the sensing element (106HF1) AMM 36-22-15-400-802.
Install BMC-2 AMM 36-11-34-400-001.

2 If the continuity resistance value is less than 8 Ohms:

Disconnect the 9240SI CONTROLLER-LOOP.
Connect again all the sensing elements or connecting cables disconnected AMM 36-22-15-400-802.
Replace BMC-2 [1HA2] AMM 36-11-34-000-001 and AMM 36-11-34-400-001.

[Rev.8 from Aug 2018] 2026.04.04 04:40:33 UTC