AN ACFT TECHNICIAN OVERHAULING AN EMB-145 MLG SHOCK STRUT FOUND A DISCREPANCY BETWEEN THE ASSEMBLY JOB CARD AND THE COMPONENT MAINT MANUAL REQUIRING A 3700 LBS PRESSURE TEST THAT WAS NOT BEING ACCOMPLISHED.

Narrative

WHILE ASSEMBLING SHOCK STRUT 2309-3002-505 FOUND A DISCREPANCY BTWN ASSEMBLY CARD 145MG-AND CMM (COMPONENT MAINT MANUAL) 32-10-00. THE ASSEMBLY REQUIRES A PRESSURE TEST OF 350 +/-10 PSI AND THE TESTING AND FAULT ISOLATION REQUIRES THE FOLLOWING TESTS; PROOF TEST; EXTENDED LEAKAGE TEST AND CYCLING TEST; FUNCTIONAL TEST AND LEAKAGE TEST; IN THE HORIZ POS. SUPPLEMENTAL INFO FROM ACN 766640: THE ASSEMBLY CARD REQUIRED A PRESSURE TEST OF 350-360 PSI AND THE CMM REQUIRES A 3700 PSI PRESSURE TEST. SUPPLEMENTAL INFO FROM ACN 766651: WHICH COULD NOT BE ACCOMPLISHED DUE TO THE LACK OF TESTING EQUIP TO SUPPORT THIS TASK. SUPPLEMENTAL INFO FROM ACN 766638: THIS PROC WAS NOT ACCOMPLISHED. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: REPORTER STATES HE NOTED THE DISCREPANCY BETWEEN THE EMB-145 MLG SHOCK STRUT ASSEMBLY BUILD-UP JOB CARD AND THE COMPONENT MAINT MANUAL (CMM) WHEN REVIEWING THE PAPERWORK; DURING HIS FIRST STRUT OVERHAUL. THE CMM REQUIRED A 3700 LBS PSI NITROGEN PRESSURE TESTS OF THE FINAL SHOCK STRUT ASSEMBLY. THIS PART OF THE PROCEDURE WAS NOT BEING DONE AND HAD NOT BEEN DONE FOR AT LEAST 13 OTHER SHOCK ASSEMBLIES THAT HAD ALREADY BEEN RELEASED FOR SERVICE. THE REASON GIVEN TO HIM WAS THE REPAIR SHOP DID NOT HAVE THE TOOLING NOR THE TEST STAND TO PERFORM THIS TYPE OF HIGH PRESSURE TESTS IN THEIR SHOP. REPORTER ALSO STATED HE THEN ASKED WHERE WAS THE ENGINEERING DOCUMENT TO GIVE MECHANIC AND INSPECTORS EXEMPTION FROM THE 3700 LBS REQUIRED PRESSURE TESTS. THE GENERAL COMMENTS WERE THIS WAS A VERBAL UNDERSTANDING FROM ENGINEERING; BUT STILL NO ACTUAL WRITTEN DOCUMENT. EMBRAER HAS SINCE STATED THE 3700 LBS PSI TESTS ARE REQUIRED. THE MFG OF THE MLG IS LIEB-AIR. CALLBACK CONVERSATION WITH RPTR ACN 766638 REVEALED THE FOLLOWING INFO: REPORTER STATED THIS SHOCK STRUT IS NOT THE TRADITIONAL MLG STRUT FOUND ON HEAVY ACFT; BUT IS ACTUALLY A CANTILEVER DESIGNED GEAR WITH THE SHOCK STRUT (ACTUATOR) MOUNTED TO THE AFT SIDE OF THE MLG AND IS A LINE REPLACEABLE UNIT (LRU). REPORTER ALSO STATED THAT SINCE THE LACK OF ANY WRITTEN ENGINEERING DOCUMENT BECAME KNOWN; HIS COMPANY HAS SET UP THE REQUIRED TESTING IN THEIR HYDRAULIC SHOP TO COMPLETE THE FINAL PAPERWORK. NO REVISION OR 'EXEMPTION' WAS EVER ISSUED. THE OTHER UNITS IN SERVICE; WITHOUT THE HIGH PRESSURE TESTS; WOULD BE BROUGHT BACK INTO SHOP ON AN ATTRITION BASIS.