MAINTENANCE TIP
**** Hidden Message ***** WASHINGTON 98124-2207737 MT 36-003 R1
20 December 2006
SUBJECT PNEUMATIC SYSTEM TROUBLESHOOTING
APPLICABILITY All 737-300/-400/-500/-600/-700/-800/-900 Airplanes
CONDITION Several operators have requested an abbreviated guide for pneumatic
system troubleshooting when using reference /C/ FIM Task.
RECOMMENDED
ACTION
Operators may wish to use the attached guide for reference while
performing pneumatic system troubleshooting per the reference /A/, /B/,
or /C/ procedures.
BACKGROUND Several operators have requested an abbreviated guide for pneumatic
system troubleshooting when using the reference /C/ FIM Task. Boeing
created the attached table in response to operators request for an engine
bleed system troubleshooting guide for using the APU pneumatic
supply.
REFERENCE a) 737-300/400/500 Aircraft Maintenance Manual 36-11-05
b) 737-600/700/800/900 Aircraft Maintenance Manual 36-11-00
c) 737-600/700/800/900 Fault Isolation Manual 36-10, Task 804
Original: Dated: 19 September 2006.
Revision: Revised to include Classic and NG AMM references
Attachment: Engine Bleed System Check
ATTACHMENT To: 737 MT 36-003
20 December 2006
Page 1 of 5
Engine Bleed System Check
STEP 737-300/400/500 737-600/700/800/900 Troubleshooting Step Expectation –
Normal Operation
Anomaly Observation
1
AMM 36-11-05
Para 11.E.(7)
AMM 36-11-00/500
Task 36-11-00-700-802
Para 6.F.(6)
FIM 36-10-804, F.(6)
Open the Thrust Reverser
2.A
AMM 36-11-05
Para 11.E.(10)
AMM 36-11-00/500
Task 36-11-00-700-802
Para 6.F.(9)
FIM 36-10-804, F.(10)
Look at the position
indicator on the high stage
valve
Should be CLOSED
2.B
AMM 36-11-05
Para 11.E.(10)(a)
AMM 36-11-00/500
Task 36-11-00-700-802
Para 6.F.(9)(a)
FIM 36-10-804, F.(10)(a)
Manually wrench OPEN
the high stage valve and
allow it to move CLOSED
by spring force only
Should move smoothly
to the OPEN position
and return to the
CLOSED position by
spring force only.
If valve does not
move smoothly and
return to CLOSED,
replace per AMM 36-
11-06/400 series
pages.
3.A
AMM 36-11-05
Para 11.E.(9)
AMM 36-11-00/500
Task 36-11-00-700-802
Para 6.F.(8)
FIM 36-10-804, F.(9)
Look at the position
indication on the Pressure
Regulating Shutoff Valve
(PRSOV)
Should be CLOSED
3.B
AMM 36-11-05
Para 11.E.(9)(a)
AMM 36-11-00/500
Task 36-11-00-700-802
Para 6.F.(9)(a)
Manually wrench OPEN
the PRSOV and allow it to
move CLOSED by spring
force only
Should move smoothly
to the OPEN position
and return to the
CLOSED position by
spring force only.
If valve does not
move smoothly and
return to CLOSED,
replace per AMM 36-
11-04/400 series
pages.
ATTACHMENT To: 737 MT 36-003
20 December 2006
Page 2 of 5
Engine Bleed System Check
STEP 737-300/400/500 737-600/700/800/900 Troubleshooting Step Expectation –
Normal Operation
Anomaly Observation
4.A
AMM 36-11-05
Para 11.E.(8)
AMM 36-11-00/500
Task 36-11-00-700-802
Para 6.F.(7)
FIM 36-10-804, F.(7)
Look at the position
indicator on the precooler
control valve
Should be OPEN
4.B
AMM 36-11-05
Para 11.E.(8)(a)
AMM 36-11-00/500
Task 36-10-00-810-802
Para 6.F.(7)(a)
FIM 36-10-804, F.(7)(a)
Manually wrench CLOSE
the precooler control valve
and allow it to move
OPEN by spring force only
Should move smoothly
to the CLOSED position
and return to the OPEN
position by spring force
only.
If valve does not
move smoothly and
return to OPEN,
replace per AMM 36-
12-02/400 series
pages.
5.
AMM 36-11-05
Para 11.F.(1)
AMM 36-11-00/500
Task 36-11-00-700-802
Para 6.G.(1)(a)
FIM 36-10-804, F.(11)
Supply pneumatic
pressure from APU or
ground supply (pressure
should be less than 40
psig)
5.A
AMM 36-11-05
Para 11.F.(7)
AMM 36-11-00/500
Task 36-11-00-700-802
Para 6.G.(8)
FIM 36-10-804, F.(15)
Disconnect the supply line
connection from the high
stage regulator port.
No air should flow from
the supply port.
If air flows from the
supply port, the
reverse flow
diaphragm is
ruptured. Replace
the high stage
regulator per AMM
36-11-07/400 series
pages.
ATTACHMENT To: 737 MT 36-003
20 December 2006
Page 3 of 5
Engine Bleed System Check
STEP 737-300/400/500 737-600/700/800/900 Troubleshooting
Step
Expectation –
Normal Operation
Anomaly Observation
5.B
AMM 36-11-05
Para 11.F.(4)
AMM 36-11-00/500
Task 36-11-00-700-802
Para 6.G.(3)
FIM 36-10-804, F.(13)
Manually OPEN the
PRSOV with a wrench,
if it does not OPEN
when the APU bleed is
selected ON.
CAUTION: Use a
ratchet-type wrench
when opening the
PRSOV to avoid
pinching fingers
Expectation is the
PRSOV will move to
and stay FULL OPEN.
Low control pressure
from the BAR or leaking
control pressure lines
can result in low duct
pressure when the
PRSOV is regulating
the pneumatic
pressure.
Check for leaking relief
valve on the bleed air
regulator (BAR),
leaking flex line to the
PRSOV, leaking control
pressure line from the
PRSOV to the 450 F
sensor, excessive
venting of the 450 F
sensor.
Check for leaks on;
- the supply
and control
pressure
lines.
- Relief valve
on the
regulator
If relief valve is
leaking, replace bleed
air regulator per AMM
36-11-03/400 series
pages.
5.C
AMM 36-11-05
Para 11.F.(5)
AMM 36-11-00/500
Task 36-11-00-700-802
Para 6.G.(4)
FIM 36-10-804, F.(20)
When the PRSOV is
opened, the precooler
control valve should
move CLOSED
Expectation; the
precooler control valve
moves to the CLOSED
position.
If valve does not
move CLOSED: check
for leaks on;
- the supply
and control
pressure
lines.
If no leaks are found;
replace the precooler
control valve per AMM
36-12-02/400 series
ATTACHMENT To: 737 MT 36-003
20 December 2006
Page 4 of 5
pages.
ATTACHMENT To: 737 MT 36-003
20 December 2006
Page 5 of 5
Engine Bleed System Check
STEP 737-300/400/500 737-600/700/800/900 Troubleshooting
Step
Expectation –
Normal Operation
Anomaly Observation
5.D
N/A, Classic
airplanes do not
have a test cap in
the control pressure
line.
AMM 36-11-00/500
Task 36-11-00-700-802
Para 6.G.(5)
FIM 36-10-804, F.(21)(a)
Disconnect test cap
on the precooler
control valve control
pressure line
Expectation; the
precooler control valve
should move OPEN.
If valve does not
move OPEN; check
for blockage in the
sense line.
6.A
AMM 36-11-00/500
Task 36-11-00-700-802
Para 6.H.(1) – (3)
Return pneumatic
system to normal
configuration.
6.B
AMM 36-11-00/500
Task 36-11-00-700-802
Para 6.H.(4), (5)
Return airplane to
normal configuration. MAINTENANCE TIP
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