Narrative:

It has come to my attention that during recent replacements of the B737-700 horizontal stabilizer jackscrews; the bolts and washers depicted in the ipc 27-41-71-01; items 100 and 105 are not being installed in new units during replacements. When jackscrews are replaced at hangar ron we have a crew of three mechanics. Due to space constraints; only two are in the aft compartment removing the jackscrew unit and one is in the forward east&east relieving cable tension to allow removal of the manual trim cable. To the best of my knowledge when I have been involved in the actual removal of the jackscrew units from the aft compartment; I have found these bolts and the washers installed on the old units and have swapped them over to the newly installed unit. However; when I was involved in a jackscrew replacement and I was the mechanic relieving cable tension; I cannot say with certainty that these bolts and washers were installed in the new units. Being part of the whole jackscrew replacement process; I may have signed off on newly installed units without knowing for sure if the mechanics in the aft compartment installed these bolts and washers. I'm filling out this report to ensure that all jackscrew replacements I have been involved with are rechked for safety. I feel that mechanics may be leaving these bolts and washers out of the B737-700 jackscrews possibly because the B737-300/-500 jackscrews do not have them installed at all in that location. It should be also noted that the B737-700 maintenance manual 27-41-81-04; paragraph 24F; step 9B tells the mechanic to remove these bolts and washers from the safety strap; and the bolts and washers in question are actually located on the jackscrew itself. This may lead a mechanic to believe that the picture is slightly inaccurate in terms of what bolts are being specified for removal because the two bolts (and nuts and washers; which the MM does not mention) for each of the safety straps; and the safety strap itself must be removed in order to remove the jackscrew unit.callback conversation with reporter acn 718707 revealed the following information: the reporter stated the B737-700 jackscrew is different from the B737-300 and -500 in that it has a fail safe lug on the bottom of the jackscrew. The reporter stated bolts and washers that screw into the lugs were not installed for various reasons; one being; the B737-300 and -500 did not have the fail safe lugs. The second; the maintenance manual directs the technician to remove these bolts and washers from the safety strap when the bolts and washers are actually located on the jackscrew. The serviceable jackscrews are delivered missing the bolts and washers; giving the wrong idea that the bolts and washers are not necessary.supplemental information from acn 718698: during my most recent stabilizer jackscrew change I noticed hardware installed reference ipc 27-14-71-01 items 100 and 105. I have to the best of my knowledge removed and replaced +/- 10 jackscrews (stabilizer) without this hardware installed; due to jackscrew not coming in with bolts and washers installed and or new jackscrew from vendor not having hardware installed. Maintenance manual 27-41-81-4 F9B is to remove this hardware. There is no step to remove 2 bolts and nut to attach fail safe strap. Jackscrew cannot be removed without removing safety straps with or without bolts and washers in question installed. Maintenance manual 27-41-81-4 5L is to install bolts and washers. You cannot install jackscrew with safety straps installed. You can; however; remove safety straps with bolts and washers installed on jackscrew. B737-300/B737-500 aircraft do not have this hardware. B737-300 you must also remove straps for right&right of jackscrew. Ipc reference 27-41-71-01.callback conversation with reporter acn 718698 revealed the following information: the reporter stated that during a recent B737-700 stabilizer jackscrew replacement; it was discovered that bolts and washers items 100 and 105 in illustrated parts catalog 24-41-71-01 were not being installed mainly because theserviceable jackscrew does not have this hardware installed. The reporter stated the maintenance manual procedure is not clear on the installation of the bolts and washers.supplemental information from acn 708706: problem arose when a mechanic noticed missing hardware on stabilizer trim actuator during removal. Hardware was not installed on previous airplanes after further research.callback conversation with reporter acn 708706 revealed the following information: the reporter stated inspection of several of the B737-700 jackscrews that were released for service missing the bolts and washers that thread into the fail safe lugs. B737-300 and -500 jackscrews did not have this hardware at the bottom of the jackscrew. The maintenance manual should have noted the B737-700 jackscrew differences and called attention to the different illustrated parts catalog added items.supplemental information from acn 718710: I was informed that several jackscrews that I inspected were possibly missing the bolts and washers that go into the fail safe lugs on the bottom of the stabilizer jackscrew. I believe part of the reason I may have missed the bolts and washers not being installed is that we were use to doing jackscrew right&right and they do not have these bolts and washers installed. I also believe that on some of the jackscrews that we right&right'd did not come in with these bolts and washers installed on it.callback conversation with reporter acn 718710 revealed the following information: the reporter stated he was advised that inspectors were missing finding the bolts and washer installation on the fail safe lugs on the B737-700 jackscrews. This was because this facility has been replacing B737-300 jackscrews for quite awhile and those jackscrews do not have the fail safe lug washers and bolts. The serviceable jackscrews delivered by the vendor are delivered with the hardware missing. The maintenance manual and job card have been revised to note the differences in the jackscrews and added hardware.

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Original NASA ASRS Text

Title: SEVERAL B737-700 ACFT WERE RELEASED FOR SVC AFTER STABILIZER JACKSCREW REPLACEMENT WITH REQUIRED BOLTS AND WASHERS THAT THREAD INTO THE FAIL SAFE LUGS ON BOTTOM OF THE JACKSCREW THAT WERE NOT INSTALLED.

Narrative: IT HAS COME TO MY ATTENTION THAT DURING RECENT REPLACEMENTS OF THE B737-700 HORIZONTAL STABILIZER JACKSCREWS; THE BOLTS AND WASHERS DEPICTED IN THE IPC 27-41-71-01; ITEMS 100 AND 105 ARE NOT BEING INSTALLED IN NEW UNITS DURING REPLACEMENTS. WHEN JACKSCREWS ARE REPLACED AT HANGAR RON WE HAVE A CREW OF THREE MECHANICS. DUE TO SPACE CONSTRAINTS; ONLY TWO ARE IN THE AFT COMPARTMENT REMOVING THE JACKSCREW UNIT AND ONE IS IN THE FORWARD E&E RELIEVING CABLE TENSION TO ALLOW REMOVAL OF THE MANUAL TRIM CABLE. TO THE BEST OF MY KNOWLEDGE WHEN I HAVE BEEN INVOLVED IN THE ACTUAL REMOVAL OF THE JACKSCREW UNITS FROM THE AFT COMPARTMENT; I HAVE FOUND THESE BOLTS AND THE WASHERS INSTALLED ON THE OLD UNITS AND HAVE SWAPPED THEM OVER TO THE NEWLY INSTALLED UNIT. HOWEVER; WHEN I WAS INVOLVED IN A JACKSCREW REPLACEMENT AND I WAS THE MECHANIC RELIEVING CABLE TENSION; I CANNOT SAY WITH CERTAINTY THAT THESE BOLTS AND WASHERS WERE INSTALLED IN THE NEW UNITS. BEING PART OF THE WHOLE JACKSCREW REPLACEMENT PROCESS; I MAY HAVE SIGNED OFF ON NEWLY INSTALLED UNITS WITHOUT KNOWING FOR SURE IF THE MECHANICS IN THE AFT COMPARTMENT INSTALLED THESE BOLTS AND WASHERS. I'M FILLING OUT THIS RPT TO ENSURE THAT ALL JACKSCREW REPLACEMENTS I HAVE BEEN INVOLVED WITH ARE RECHKED FOR SAFETY. I FEEL THAT MECHANICS MAY BE LEAVING THESE BOLTS AND WASHERS OUT OF THE B737-700 JACKSCREWS POSSIBLY BECAUSE THE B737-300/-500 JACKSCREWS DO NOT HAVE THEM INSTALLED AT ALL IN THAT LOCATION. IT SHOULD BE ALSO NOTED THAT THE B737-700 MAINT MANUAL 27-41-81-04; PARAGRAPH 24F; STEP 9B TELLS THE MECHANIC TO REMOVE THESE BOLTS AND WASHERS FROM THE SAFETY STRAP; AND THE BOLTS AND WASHERS IN QUESTION ARE ACTUALLY LOCATED ON THE JACKSCREW ITSELF. THIS MAY LEAD A MECHANIC TO BELIEVE THAT THE PICTURE IS SLIGHTLY INACCURATE IN TERMS OF WHAT BOLTS ARE BEING SPECIFIED FOR REMOVAL BECAUSE THE TWO BOLTS (AND NUTS AND WASHERS; WHICH THE MM DOES NOT MENTION) FOR EACH OF THE SAFETY STRAPS; AND THE SAFETY STRAP ITSELF MUST BE REMOVED IN ORDER TO REMOVE THE JACKSCREW UNIT.CALLBACK CONVERSATION WITH RPTR ACN 718707 REVEALED THE FOLLOWING INFO: THE RPTR STATED THE B737-700 JACKSCREW IS DIFFERENT FROM THE B737-300 AND -500 IN THAT IT HAS A FAIL SAFE LUG ON THE BOTTOM OF THE JACKSCREW. THE RPTR STATED BOLTS AND WASHERS THAT SCREW INTO THE LUGS WERE NOT INSTALLED FOR VARIOUS REASONS; ONE BEING; THE B737-300 AND -500 DID NOT HAVE THE FAIL SAFE LUGS. THE SECOND; THE MAINT MANUAL DIRECTS THE TECHNICIAN TO REMOVE THESE BOLTS AND WASHERS FROM THE SAFETY STRAP WHEN THE BOLTS AND WASHERS ARE ACTUALLY LOCATED ON THE JACKSCREW. THE SERVICEABLE JACKSCREWS ARE DELIVERED MISSING THE BOLTS AND WASHERS; GIVING THE WRONG IDEA THAT THE BOLTS AND WASHERS ARE NOT NECESSARY.SUPPLEMENTAL INFO FROM ACN 718698: DURING MY MOST RECENT STABILIZER JACKSCREW CHANGE I NOTICED HARDWARE INSTALLED REF IPC 27-14-71-01 ITEMS 100 AND 105. I HAVE TO THE BEST OF MY KNOWLEDGE REMOVED AND REPLACED +/- 10 JACKSCREWS (STAB) WITHOUT THIS HARDWARE INSTALLED; DUE TO JACKSCREW NOT COMING IN WITH BOLTS AND WASHERS INSTALLED AND OR NEW JACKSCREW FROM VENDOR NOT HAVING HARDWARE INSTALLED. MAINT MANUAL 27-41-81-4 F9B IS TO REMOVE THIS HARDWARE. THERE IS NO STEP TO REMOVE 2 BOLTS AND NUT TO ATTACH FAIL SAFE STRAP. JACKSCREW CANNOT BE REMOVED WITHOUT REMOVING SAFETY STRAPS WITH OR WITHOUT BOLTS AND WASHERS IN QUESTION INSTALLED. MAINT MANUAL 27-41-81-4 5L IS TO INSTALL BOLTS AND WASHERS. YOU CANNOT INSTALL JACKSCREW WITH SAFETY STRAPS INSTALLED. YOU CAN; HOWEVER; REMOVE SAFETY STRAPS WITH BOLTS AND WASHERS INSTALLED ON JACKSCREW. B737-300/B737-500 ACFT DO NOT HAVE THIS HARDWARE. B737-300 YOU MUST ALSO REMOVE STRAPS FOR R&R OF JACKSCREW. IPC REF 27-41-71-01.CALLBACK CONVERSATION WITH RPTR ACN 718698 REVEALED THE FOLLOWING INFO: THE RPTR STATED THAT DURING A RECENT B737-700 STABILIZER JACKSCREW REPLACEMENT; IT WAS DISCOVERED THAT BOLTS AND WASHERS ITEMS 100 AND 105 IN ILLUSTRATED PARTS CATALOG 24-41-71-01 WERE NOT BEING INSTALLED MAINLY BECAUSE THESERVICEABLE JACKSCREW DOES NOT HAVE THIS HARDWARE INSTALLED. THE RPTR STATED THE MAINT MANUAL PROC IS NOT CLR ON THE INSTALLATION OF THE BOLTS AND WASHERS.SUPPLEMENTAL INFO FROM ACN 708706: PROB AROSE WHEN A MECHANIC NOTICED MISSING HARDWARE ON STAB TRIM ACTUATOR DURING REMOVAL. HARDWARE WAS NOT INSTALLED ON PREVIOUS AIRPLANES AFTER FURTHER RESEARCH.CALLBACK CONVERSATION WITH RPTR ACN 708706 REVEALED THE FOLLOWING INFO: THE RPTR STATED INSPECTION OF SEVERAL OF THE B737-700 JACKSCREWS THAT WERE RELEASED FOR SVC MISSING THE BOLTS AND WASHERS THAT THREAD INTO THE FAIL SAFE LUGS. B737-300 AND -500 JACKSCREWS DID NOT HAVE THIS HARDWARE AT THE BOTTOM OF THE JACKSCREW. THE MAINT MANUAL SHOULD HAVE NOTED THE B737-700 JACKSCREW DIFFERENCES AND CALLED ATTENTION TO THE DIFFERENT ILLUSTRATED PARTS CATALOG ADDED ITEMS.SUPPLEMENTAL INFO FROM ACN 718710: I WAS INFORMED THAT SEVERAL JACKSCREWS THAT I INSPECTED WERE POSSIBLY MISSING THE BOLTS AND WASHERS THAT GO INTO THE FAIL SAFE LUGS ON THE BOTTOM OF THE STAB JACKSCREW. I BELIEVE PART OF THE REASON I MAY HAVE MISSED THE BOLTS AND WASHERS NOT BEING INSTALLED IS THAT WE WERE USE TO DOING JACKSCREW R&R AND THEY DO NOT HAVE THESE BOLTS AND WASHERS INSTALLED. I ALSO BELIEVE THAT ON SOME OF THE JACKSCREWS THAT WE R&R'D DID NOT COME IN WITH THESE BOLTS AND WASHERS INSTALLED ON IT.CALLBACK CONVERSATION WITH RPTR ACN 718710 REVEALED THE FOLLOWING INFO: THE REPORTER STATED HE WAS ADVISED THAT INSPECTORS WERE MISSING FINDING THE BOLTS AND WASHER INSTALLATION ON THE FAIL SAFE LUGS ON THE B737-700 JACKSCREWS. THIS WAS BECAUSE THIS FACILITY HAS BEEN REPLACING B737-300 JACKSCREWS FOR QUITE AWHILE AND THOSE JACKSCREWS DO NOT HAVE THE FAIL SAFE LUG WASHERS AND BOLTS. THE SERVICEABLE JACKSCREWS DELIVERED BY THE VENDOR ARE DELIVERED WITH THE HARDWARE MISSING. THE MAINTENANCE MANUAL AND JOB CARD HAVE BEEN REVISED TO NOTE THE DIFFERENCES IN THE JACKSCREWS AND ADDED HARDWARE.

Data retrieved from NASA's ASRS site as of January 2009 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.