Narrative:

During an aft engine mount build up, it was discovered the center link assembly may have been installed incorrectly. There was a brand new aft engine mount assembly for boeing sitting on the bench. I noticed the center link assembly was installed differently. It is possible the link assembly could have been installed incorrectly. There had also been a B737-700 engine sitting in the shop with a boeing built aft engine mount assembly installed, and it was like the new mount. This immediately raised a red flag. Air carrier from step east, does not specify the orientation of the link. Air carrier from (installing aft mount to engine) step C and D, which pertains to installing the two center bolts, doesn't mention anything about one bolt being looser than the other. Both forms need changes to bring this to your attention either building the aft mount assembly or installing the mount to the engine as to what to look for. Callback conversation with reporter revealed the following information: the reporter stated the link assembly for the aft motor mount build up can be installed two ways one of which is wrong. The reporter said the boeing aircraft company job card just directs the tech to install the link on the aft engine mount then moves on to a step unrelated to the link assembly. The reporter stated the link, shaped like a boomerang, has two small holes and one large. When looking at the link, one small hole is on the left, another small hole at the apex, and a large hole on the right. The reporter said rotating the link 180 degrees, the holes will align and bolts can be inserted. The reporter stated pwrplant engineering was alerted and boeing aircraft company will revise the manual to ensure correct installation. The reporter stated the FAA has become involved and interviewed shop techs.

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Original NASA ASRS Text

Title: AN ENG SHOP TECH RPTS SOME B737-700 ENGS MAY HAVE THE AFT ENG MOUNT LINK ASSEMBLED INCORRECTLY. CAUSED BY A PUBLICATION DEFICIENCY.

Narrative: DURING AN AFT ENG MOUNT BUILD UP, IT WAS DISCOVERED THE CENTER LINK ASSEMBLY MAY HAVE BEEN INSTALLED INCORRECTLY. THERE WAS A BRAND NEW AFT ENG MOUNT ASSEMBLY FOR BOEING SITTING ON THE BENCH. I NOTICED THE CENTER LINK ASSEMBLY WAS INSTALLED DIFFERENTLY. IT IS POSSIBLE THE LINK ASSEMBLY COULD HAVE BEEN INSTALLED INCORRECTLY. THERE HAD ALSO BEEN A B737-700 ENG SITTING IN THE SHOP WITH A BOEING BUILT AFT ENG MOUNT ASSEMBLY INSTALLED, AND IT WAS LIKE THE NEW MOUNT. THIS IMMEDIATELY RAISED A RED FLAG. ACR FROM STEP E, DOES NOT SPECIFY THE ORIENTATION OF THE LINK. ACR FROM (INSTALLING AFT MOUNT TO ENG) STEP C AND D, WHICH PERTAINS TO INSTALLING THE TWO CENTER BOLTS, DOESN'T MENTION ANYTHING ABOUT ONE BOLT BEING LOOSER THAN THE OTHER. BOTH FORMS NEED CHANGES TO BRING THIS TO YOUR ATTENTION EITHER BUILDING THE AFT MOUNT ASSEMBLY OR INSTALLING THE MOUNT TO THE ENG AS TO WHAT TO LOOK FOR. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE LINK ASSEMBLY FOR THE AFT MOTOR MOUNT BUILD UP CAN BE INSTALLED TWO WAYS ONE OF WHICH IS WRONG. THE RPTR SAID THE BOEING ACFT COMPANY JOB CARD JUST DIRECTS THE TECH TO INSTALL THE LINK ON THE AFT ENG MOUNT THEN MOVES ON TO A STEP UNRELATED TO THE LINK ASSEMBLY. THE RPTR STATED THE LINK, SHAPED LIKE A BOOMERANG, HAS TWO SMALL HOLES AND ONE LARGE. WHEN LOOKING AT THE LINK, ONE SMALL HOLE IS ON THE LEFT, ANOTHER SMALL HOLE AT THE APEX, AND A LARGE HOLE ON THE RIGHT. THE RPTR SAID ROTATING THE LINK 180 DEGS, THE HOLES WILL ALIGN AND BOLTS CAN BE INSERTED. THE RPTR STATED PWRPLANT ENGINEERING WAS ALERTED AND BOEING ACFT COMPANY WILL REVISE THE MANUAL TO ENSURE CORRECT INSTALLATION. THE RPTR STATED THE FAA HAS BECOME INVOLVED AND INTERVIEWED SHOP TECHS.

Data retrieved from NASA's ASRS site as of July 2007 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.