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WASHINGTON 98124-2207 737 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.

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