Narrative:

Note: this maintenance report applies to all company dc-10 aircraft; not just aircraft X. The pressure regulating shutoff valve (prsov) and overpressure shutoff valve (opsov) connections to all tras lock engine duel switcher valves are not connected properly. It has been verified via company engineering that the prsov valve is actually connected to the dual switcher valve opsov connection and the opsov valve is actually connected to the dual switcher valve prsov connection. The connections are backwards. This is causing some thrust reversers to stow during auto re-stow testing in maintenance. If the lines were properly connected; the thrust reverser would not be able to stow during testing. Flight safety - it has always been my understanding that the opsov is solenoid controlled air to the dual switcher valve. A company engineer recently pointed out that engine air is actually at the dual switcher valve anytime the engine is running. He showed me the [mcdonnell-douglas] lamm schematic which shows the air flow to the dual switcher valve with no solenoid control. The prsov valve could be open in flight as it is on the ground during the auto re-stow test as a result of the lines being connected backwards. [Recommend] to properly connect the lines to the dual switcher valve. Verify if the opsov air is still solenoid controlled air. If not; then we must connect the lines to the dual switcher vavle properly. If the opsov is solenoid operated; then inform engineering and change the lamm [schematic] to reflect this.

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Original NASA ASRS Text

Title: An Aircraft Maintenance Technician (AMT) with extensive DC-10 Engine Reverser experience describes what he believes to be inaccurate Boeing Lamm schematics that have contributed to engine pneumatic lines being attached at incorrect positions on Dual Switcher Valves on GE-CF6-80 engines. The Switcher Valves are part of the FAAs Thrust Reverser Safety Enhancement System A.D.

Narrative: NOTE: This Maintenance report applies to all company DC-10 Aircraft; not just Aircraft X. The Pressure Regulating Shutoff Valve (PRSOV) and Overpressure Shutoff Valve (OPSOV) connections to all TRAS Lock Engine Duel Switcher valves are not connected properly. It has been verified via company Engineering that the PRSOV valve is actually connected to the Dual Switcher Valve OPSOV connection and the OPSOV valve is actually connected to the Dual Switcher Valve PRSOV connection. The connections are backwards. This is causing some Thrust Reversers to stow during Auto Re-Stow Testing in Maintenance. If the lines were properly connected; the Thrust Reverser would not be able to stow during testing. Flight Safety - It has always been my understanding that the OPSOV is solenoid controlled air to the Dual Switcher Valve. A company Engineer recently pointed out that engine air is actually at the Dual Switcher Valve anytime the engine is running. He showed me the [McDonnell-Douglas] LAMM schematic which shows the air flow to the Dual Switcher Valve with no solenoid control. The PRSOV valve could be open in flight as it is on the ground during the Auto Re-Stow test as a result of the lines being connected backwards. [Recommend] to properly connect the lines to the Dual Switcher Valve. Verify if the OPSOV air is still solenoid controlled air. If not; then we must connect the lines to the Dual Switcher Vavle properly. If the OPSOV is solenoid operated; then inform Engineering and change the LAMM [schematic] to reflect this.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.