A Line Mechanic reported his efforts to have an Engineering Order (E/O) corrected that involved the installation of two metal straps across an access door in their crew compartment rest area on their B747-400 aircraft.
Synopsis
A Line Mechanic reported his efforts to have an Engineering Order (E/O) corrected that involved the installation of two metal straps across an access door in their crew compartment rest area on their B747-400 aircraft.
Narrative
An Engineering Order (E/O) showed to install two straps on what is labeled door-1 in the door-5 right-hand crew rest area on our B747-400 fleet. These straps cross a protruding piano hinge assembly that the door uses to open and close. From the piano hinge to the blind rivet installation nearest to it; the strap material to be secured down does not lie flush with the surface to be riveted.I contacted Maintenance Control and was told that the Engineer; Mr X; felt that this was an acceptable condition. I disagreed. For the blind rivets to attain their proper strength; the material to be riveted must be flush to one another. This problem is not allowed per our General Maintenance Manual (GMM) 1-0-8 that references that topic. GMM 1-0-8; item 8; [instructs to] pull the sheets together; form the bulb tail; swage the collar and fracture [break]; the stem.I am concerned that the rivets are being used outside of their design envelope. At some point later; an update to the Engineering Order (E/O) was added; stating that the 3/16th to 1/4 inch gap between the strap and the attach surface was acceptable. It gave no reference to how this decision was made. I have been involved with several of these installations and this issue has affected all that I've done.
NASA callback
Reporter stated their Engineering Order (E/O) was written to satisfy a TSA concern about the possibility of a public person gaining access to the aft side of their crew rest area compartment and hiding out on small eight inch ledge between the crew compartment bulkhead wall and the pressure side of the fuselage pressure bulkhead. This is/was an access door for maintenance. Reporter stated the Engineering Order (E/O) required a Mechanic to install two .080' thousandths thick aluminum metal straps; using 2024 T-3 aluminum; horizontally across the access door over the protruding piano hinge; using blind shear rivets. He explained to the Engineer that first of all the load on the blind rivets securing the metal straps were not a 'Shear' load but a 'Tension' load; the E/O for the type of rivets to be used; did not reflect the actual situation. The blind rivets were to be 'shot' blind; through the one inch thick crew compartment bulkhead wall and he was told not to use any shims or collars to take-up the slack (gap) between the bulkhead wall and the metal straps for a tight installation.Reporter stated he made a write-up to address the rivet installation procedure; but was told by Maintenance Control they overrode his write-up based on the Engineer's decision. He explained to Maintenance Control the rivet installation in the E/O did not follow Standard Sheet Metal Maintenance Practices or their own companies General Maintenance Manual rivet installations. But the Engineer would not change the E/O. Reporter had already signed-off the strap installation per the E/O; thinking the write-up for the rivet installation would be corrected later; but was not.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.