Hung Start/Hot Start/Stall - Effect of HPC Bleed System on Engine Operation

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1. Possible Causes
· HPC stage 7 bleed valves and solenoids
· HPC stage 10 bleed valve and solenoid
2 Job Set-up Information
A. Referenced Information
REFERENCE DESIGNATION
Ref. AMM 75-32-52-700-011 Functional Test of the HPC Stage 7 Bleed Valve with Test Set
IAE2R19437
Ref. AMM 75-32-54-700-011 Functional Test of the HPC Stage 10 Bleed Valve with Test Set
IAE2R19437
3. Fault Confirmation
Subtask 75-00-00-869-051-A
A. Not Applicable.
(1) Refer to (Ref. 75-00-00 Page Block 301 Task Supporting Data).
NOTE: This information is supplemental to the remain relevant TSM task which instructs the correct
fault isolation procedures and should only be used when bleed valve inspections are referenced
to within those tasks.
4. Fault Isolation
Subtask 75-00-00-810-058-A
A. Hung starts (unsuccessful starts which can be accompanied by high EGT)
Refer to the task supporting data (Ref. 75-00-00 Page Block 301 Task Supporting Data).
(1) If the engine fails in manual start, but is successfull in auto start:
· Visually inspect the servo air supply pipes from the solenoids to the handling bleed valves for signs
of loose connections at the solenoid valves bifurcation panel and bleed valves.
· Visually inspect the compressor exit air supply pipe from the top of the rear high pressure
compressor casing to the solenoid valves for signs of loose connections over the pipe extensions at
the bifurcation panel and solenoid valves.
(2) If no fault is found:
· do a functional test of the HPC stage 7 bleed valves and solenoids Ref. AMM 75-32-52-700-011
· do a functional test of the HPC stage 10 bleed valve and solenoid Ref. AMM 75-32-54-700-011
NOTE: For the functional testing of the HPC bleed valves, the test set vacuum pipe must be connected
to the servo air pipes as described in the referred AMM task not following the alternative
method (see note in the referred AMM tasks).
Subtask 75-00-00-810-059-A
CAUTION: IF INCREASE IN EGT IS SUFFICIENT TO SET AN EGT EXCEEDANCE/ OVERLIMIT, THEN
THE FULL PROCEDURE FOR THAT OBSERVATION/ECAM WARNING MUST BE FOLLOWED.
B. Hot starts (successful starts which are accompanied by high EGT)
Refer to the task supporting data (Ref. 75-00-00 Page Block 301 Task Supporting Data).
(1) Make a note of the EGT and fuel flow parameter shifts (increases) on the subject engine.
(2) Ensure that the max. EGT is not above the limit.
(3) Identify which of the fuel flow and EGT parameter shifts (increases) at engine idle as shown below
correspond to those recorded in para. (1):
(a) Stage 7 (ground idle)
· Delta EGT : 15 to 35 (°C)
· Delta FF : 3 to 7 (%)
(b) Stage 10 (ground idle)
· Delta EGT : 35 to 65 (°C)
· Delta FF : 9 ot 16 (%)
(4) On the MCDU, read the LAST LEG REPORT to check that there are no FADEC monitored faults
indicating that a solenoid valve electrical failure has occurred (Ref. 70-00-00 Page Block 301 Task
Supporting Data).
(a) If there is a FADEC fault present, troubleshoot in accordance with the relevant TSM procedure.
(5) Do a functional test of the relevant HPC bleed valve(s) and solenoid(s) Ref. AMM 75-32-52-700-011 ,
Ref. AMM 75-32-54-700-011 .
Subtask 75-00-00-810-060-A
CAUTION: IF INCREASE IN EGT IS SUFFICIENT TO SET AN EGT EXCEEDANCE/ OVERLIMIT, THEN
THE FULL PROCEDURE FOR THAT OBSERVATION/ECAM WARNING MUST BE FOLLOWED.
C. Engine parameter shift/mismatch during climb/cruise.
Refer to the task supporting data (Ref. 75-00-00 Page Block 301 Task Supporting Data).
(1) Make a note of the EGT and fuel flow (FF) parameter shifts (increases) on the subject engine and the
corresponding flight phase at the time recording.
(2) Identify which of the fuel flow and EGT parameter shift (increases) at engine idle as shown below
correspond to those recorded in para.(1) for the relevant flight phase :
(a) Take-off
· stage 7 : delta EGT 30 to 55 (°C), delta FF 4 to 8 (%)
· stage 10 : delta EGT 90 to 120 (°C), delta FF 13 to 18 (%)
(b) Climb/cruise
· stage 7 : delta EGT 25 to 45 (°C), delta FF 3 to 7 (%)
· stage 10 : delta EGT 70 to 100 (°C), delta FF 9 to 16 (%)
(3) On the MCDU, read the LAST LEG REPORT to check that there are no FADEC monitored faults
indicating that a solenoid valve electrical failure has occurred (Ref. 70-00-00 Page Block 301 Task
Supporting Data).
(a) If there is a FADEC fault present, troubleshoot in accordance with the relevant TSM procedure.
(4) Do a functional test of the relevant HPC bleed valve(s) and solenoid(s) Ref. AMM 75-32-52-700-011 ,
Ref. AMM 75-32-54-700-011 .
Subtask 75-00-00-810-061-A
D. Engine operation impact (transient manoeuvres and surge recovery)
Refer to the task supporting data (Ref. 75-00-00 Page Block 301 Task Supporting Data).
NOTE: If an engine surge/stall has occured, the related TSM procedure must be followed.
NOTE: For the functional testing of the HPC bleed valves, the test set vacuum pipe must be connected to
the servo air pipes as described in the referred AMM task not following the alternative method (see
note in the referred AMM tasks).
(1) If the engine stalls/surges on transient operation at idle/low power
· visually inspect the servo air supply pipes for signs of loose connections at solenoid valves,
bifurcation panel and bleed valves.
(a) If no fault is found :
· do a functional test of the HPC stage 7C bleed valve and solenoid Ref.
AMM 75-32-52-700-011
· do a functional test of the HPC stage 7A bleed valve and solenoid Ref.
AMM 75-32-52-700-011 .
(2) If the engine stalls/surges on transient operation at low/mid power
· visually inspect the servo air supply pipes for signs of loose connections at the solenoid valves,
bifurcation panel and bleed valves
(a) If no fault is found :
· do a functional test of the HPC stage 7C bleed valve and solenoid Ref.
AMM 75-32-52-700-011 .
(3) If the engine fails to recover from an engine stall/surge
· visually inspect the servo air supply pipes for signs of loose connections at the solenoid valves,
bifurcation panel and bleed valves
(a) If no fault is found :
· do a functional test of the HPC stage 7C bleed valve and solenoid Ref.
AMM 75-32-52-700-011
· do a functional test of the HPC stage 10 bleed valve and solenoid Ref.
AMM 75-32-54-700-011
· do a functional test of the HPC stage 7A bleed valve and solenoid Ref.
AMM 75-32-52-700-011 .
75-00-00 PB 301 CONF 13 - AIR - GENERAL - TASK SUPPORTING DATA
1. General
This information is intended to aid troubleshooting of engine starting problems where bleed valves may be the
cause, and to help identify if bleed valve problems have occurred during flight.
NOTE: This information is supplemental to the main relevant TSM Task which instructs the correct Fault Isolation
procedures and should only be used when bleed valve inspections are referenced to within those
tasks.
(Ref. Fig. Component Location SHEET 1)
Figure 75(IAE)-00-00-11200-A / SHEET 1/1 - Component Location not printed, as per printing preferences
(Ref. Fig. Compressor Control SHEET 1)
Figure 75(IAE)-00-00-11300-A / SHEET 1/1 - Compressor Control not printed, as per printing preferences
A. Hung Starts (unsuccessful starts which can be accompanied by high EGT)
(1) Background:
All bleed valves (3 off stage 7, 1 off stage 10) are spring loaded in the open position for engine starting.
They are held open during engine running by solenoid valve directed P3 servo air. According to
scheduling requirements, the bleed valves will close progressively during the starting cycle in the
sequence 7B, 10, 7C. The 7A valve stays open up to and above idle.
(2) Possible causes:
Hung Starts can be as a result of:
· bleed valve(s) not being open during the start and/or,
· bleed valve(s) closing early.
(a) Bleed valves not being open can be due to the bleed valve sticking in the closed
position (non-detected FADEC fault), or the solenoid sticking in the energized position
(non-detected FADEC fault).
(b) Bleed valves closing early can be due to solenoid sticking such that the full deenergized
position is not obtained (non-detected FADEC fault), bleed valve internal
seal leakage or P3 servo air leakage.
B. Hot Starts (successful starts which are accompanied by high EGT)
(1) Background:
Hot starts can occur if a bleed valve remains open after the point in the start sequence that it would
normally have closed. As a result EGT is increased. This EGT increase is not always sufficient to
register an EGT exceedance.
CAUTION : IF THE INCREASE IN EGT IS SUFFICIENT TO SET AN EGT
EXCEEDANCE/OVERLIMIT, THEN THE FULL TSM PROCEDURE FOR THAT
OBSERVATION/ECAM WARNING MUST BE FOLLOWED.
(2) Possible causes:
Hot starts can be as a result of:
· bleed valve(s) stuck open (non-detected FADEC fault) or,
· solenoid valve sticking in the de-energized position (non-detected FADEC fault) or,
· an electrical failure of the solenoid valve which results in the solenoid moving to the de-energized
position (FADEC fault).
It is possible to prioritise the order in which the bleed valve system is checked based upon the changes
in main engine parameters.
NOTE: These changes can be noted based upon previous parameter levels known for the subject engine
and/or cross-wing comparisons provided that differences in EGT margin are taken into consideration.
C. Engine Parameter Shift/Mismatch during Climb/Cruise
(1) Background:
Engine parameter shifts due an open bleed valve that are not noticed at engine start are more likely to
become evident at higher EPR power settings. This increases the likelihood of an EGT Exceedance/
Overlimit.
Additionally, an open bleed valve as a result of bleed valve system problems in flight will also result in
unexplained engine parameter shifts.
CAUTION : IF THE INCREASE IN EGT IS SUFFICIENT TO SET AN EGT
EXCEEDANCE/OVERLIMIT, THEN THE FULL TSM PROCEDURE FOR THAT
OBSERVATION/ECAM WARNING MUST BE FOLLOWED.
(2) Possible causes:
Engine parameter shift/mismatch during climb/cruise can be as a result of:
· bleed valve(s) stuck open (non-detected FADEC fault) or,
· solenoid valve sticking in the de-energized position (non-detected FADEC fault) or,
· an electrical failure of the solenoid valve which results in the solenoid moving to the de-energized
position (FADEC fault).
D. Engine Operation Impact (transient manoeuvres and surge recovery)
(1) Background:
During transient manoeuvres (acceleration/deceleration) and surge recovery, HPC stability is maintained
by opening particular bleed valves as defined by the EEC logic.
For transient manoeuvres on the ground, the 7C is opened and during flight, the 7A and 7C are opened.
(In both cases the 7C is opened based upon a transient detect and is closed after a set period of time
has elapsed).
There are no valves opened at take-off power or steady state cruise.
For surge recovery, the 7A, 7C and 10 valves are opened to maintain HPC stability.
In the event of engine problems (stall/surge) on transient operation, or an unrecoverable engine stall/
surge, it is possible to prioritise the order in which the bleed valve system is checked based upon which
valves are normally used.
CAUTION : IF AN ENGINE STALL/SURGE HAS OCCURRED, THEN THE FULL TSM PROCEDURE
FOR THAT OBSERVATION/ECAM WARNING MUST BE FOLLOWED.
(2) Possible causes:
Engine problems (stall/surge) on transient operation can be as a result of
· bleed valve(s) not being opened during the transient and/or,
· bleed valve(s) closing early.
(a) Bleed valves not being open can be due to the bleed valve sticking in the closed
position (non-detected FADEC fault), or the solenoid sticking in he energized position
(non-detected FADEC fault).
(b) Bleed valves closing early can be due to solenoid sticking such that the full deenergized
position is not obtained (non-detected FADEC fault), bleed valve internal
seal leakage or P3 servo air leakage.
Figure 75(IAE)-00-00-11200-13-A- / SHEET 1/1 - Component Location
Figure 75(IAE)-00-00-11300-13-A- / SHEET 1/1 - Compressor Control
75-23 - (IAE) - HP TURBINE COOLING
75-23-00 - (IAE) - HP TURBINE COOLING
75-23-00 PB 201 CONF 13 - HP TURBINE COOLING - FAULT ISOLATION PROCEDURES [Rev.6 from Feb 2017] 2026.04.04 04:37:13 UTC