Post by kevin5345179 on Sept 7, 2020 7:59:35 GMT 1
The manufacturer declines to say how many of the 980 787s built so far have one of the two defects. The source with knowledge of the issue confirms that “many” airframes are affected, while a second industry source says the figure is “several hundred.” Boeing acknowledges there are two separate issues but declines to discuss their scope beyond acknowledging that eight aircraft have both.
Post by kevin5345179 on Sept 8, 2020 18:16:34 GMT 1
During fabrication in Salt Lake of the 787’s horizontal tail — known as the stabilizer — engineers discovered earlier this year that “certain components were clamped together during the build process with greater force than specified,” potentially leaving the structure with gaps between components wider than the allowable specification, Boeing said.
The issue “may lead to premature aging of the part,” meaning the horizontal tail structure, Boeing said.
Post by kevin5345179 on Sept 10, 2020 23:53:05 GMT 1
so entire aft section of 787 has issue?
It's not clear what airline the the mechanic worked for, but the technician noticed something wrong on a Boeing 787 Dreamliner while working on the tail of the aircraft. The mechanic noticed a slight dimple, also known as a depression, on the vertical fin, near the spot where it joins with the aircraft's fuselage.
"This depression was located at a joint common to the Main Torque Box (MTB) skin, Rear Spar, and Route Fitting #4. Shims were properly installed prior to drilling of holes," an investigator wrote. "Investigation suggests these shims were later discarded before final fastener installation. Measurement on aircraft prior to rework show un-shimmed gaps up to 0.034.”
“The excessive gap produced a greater than design preload in the affected details,” the report found. “The increased preload combined with the design loads could exceed the limit load capability of the joint.”
The LN’s start at number 1 and go up from there.
“The affected LNs extend to LN 6-687,” the report says, which represents 681 total planes. "689-873, 875-885, 889-890, 895, 896, & 897.”