AN ACFT INSPECTOR DISCOVERED EROSION FROM BRAZING AROUND 7 DIFFERENT COMPRESSOR STATOR STAGES FOR THE JT8-217 AND -219 ENGINES VANE SLOTS AND ON VANES.

Narrative

SHOP AND REPAIRS 7 COMPRESSOR STATOR STAGES FOR JT8-217 AND JT8-219 ENGS. DISCOVERED EROSION FROM BRAZING AROUND VANE SLOTS AND ON VANES. DETERMINED THROUGH MANUFACTURER OF BRAZE AN IMPROPER MIX OF BRAZE WITH EXCESS BORON TO BE CAUSE OF EROSION. BORON ERODING PARENT MATERIAL DURING BRAZE CYCLE. BEGINNING OCT/XX; DETERMINATION DATE WHEN LAST BATCH OF BRAZE PASTE DELIVERED FROM VENDOR. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: REPORTER STATED THESE ENGINES ARE USED ON THE MD-80 ACFT. ANOTHER INSPECTOR QUESTIONED REPORTER IF HE NOTICED ANY EROSION ON THE COMPRESSOR STATOR VANE SLOTS AND VANES OF THE JT8-217 & -219 ENGINES. REALIZING THIS NOW INVOLVED MORE THAN ONE COMPRESSOR STATOR STAGE UNIT; THE INVESTIGATION REVEALED THE VENDOR MFG OF THE BRAZE PASTE HAD MADE CHANGES TO THE BATCH MIX AT THE DIRECTION OF A NEW SUPERVISOR WHO DID NOT USE PROPER QUALITY CONTROL PROCEDURES. THIS LED TO AN IMPROPER BRAZE PASTE BEING RELEASED AND SOLD WITH EXCESS BORON THAT CAUSES EROSION OF THE PARENT MATERIAL OF THE VANE SLOTS AND STATOR VANES. THIS EROSION WAS EXTENSIVE ENOUGH THAT SCRAPPING THE ENTIRE STATOR SECTION WAS MORE ECONOMICAL THAN TO ATTEMPT REPAIRS. THE BRAZE PASTE IS APPLIED IN THE VANE SLOTS WHERE THE VANE ROOT RESTS AT THE INNER AND OUTER SHROUDS; USING A CARTRIDGE WITH A BLUNT NEEDLE TYPE TIP WHILE AVOIDING ANY CONTACT WITH THE PASTE. THE STATORS ARE THEN PUT THROUGH A HEAT PROCESS WHERE THE BRAZING SECURES THE STATOR VANES IN THE INNER AND OUTER SHROUDS. REPORTER ALSO STATED HIS COMPANY HAS ISOLATED THE PREVIOUS SUSPECT BATCH AND THE KNOWN MIS-MIXED BATCH. THE MFG OF THE BRAZE PASTE HAS SINCE REVAMPED THEIR ENTIRE MIX AND QUALITY CONTROL PROCESS.