Unbelievably, yet another issue has been uncovered with Boeing’s popular widebody, the 787 Dreamliner. Again related to a shimming problem, this latest defect reportedly relates to the vertical stabilizer or tail fin. Previous issues of a similar nature have been found in recent weeks, regarding body joins and the horizontal stabilizer. This most recent issue is likely to affect almost 700 of the global Dreamliner fleet.
A fourth new problem
The problems keep coming for Boeing’s 787 Dreamliner. Once the pinnacle of clean sheet, modern aircraft design, now it seems the planemaker has some serious questions to be answered regarding the quality of its production.
Hot on the heels of no less than three previous production issues, yesterday saw a fourth problem disclosed, this time affecting the vertical stabilizer. KOMO News Radio, based in Seattle, first reported the news, citing federal records as a source.
According to the reports, the issue could affect at least 680 of the 981 Dreamliners that are currently in service. Specifically, it involves excessive gaps, which could cause strain on the structure of aircraft over time, posing a safety concern.
Reuters reports that the Federal Aviation Administration (FAA) is yet to issue an Airworthiness Directive for the fault. When asked, the agency confirmed that it is still investigating manufacturing flaws affecting some Boeing 787 aircraft, but no decision on a directive had yet been reached.
Boeing told KOMO News that,
“This issue was found in late 2019 and has already been addressed in production.”
The spokesperson further said that the issue “did not immediately affect the safety of flight and no immediate action is required,” having conducted a thorough analysis. They suggested they are working with the FAA, and that guidance is being prepared for the in-service fleet. They estimate that the issue will require a one-time inspection of the aircraft during regularly scheduled maintenance.
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What’s the latest issue?
According to KOMO News, reporting on the contents of a federal document, this is yet another shimming issue. The composite fuselage of the 787, by its nature, is difficult to produce with a completely smooth surface. As such, when joining sections together, natural microscopic gaps appear in the joins. These are filled in using a part known as a shim.
During a mechanical review, a technician discovered something untoward at the tail end of a Dreamliner. At the spot where the tail joins the fuselage, the mechanic found a small depression. Having reported this to the authorities, federal investigators began scrutinizing huge swathes of the Dreamliner fleet.
Already, this process of scrutiny has thrown up three issues, including one which caused eight aircraft to be immediately pulled from service. There was also a problem discovered with the horizontal stabilizer.
Now, it seems there are safety concerns regarding the vertical stabilizer or tail fin too. In the federal document seen by KOMO News Radio, an inspector reportedly stated,
“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. 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.”
A small gap, but a big problem
In other types of construction, a gap of 0.034 inches is barely noticeable, and certainly no cause for concern. However, in the precision engineering of a pressurized aircraft, the gap is significant. The report continued,
“The excessive gap produced a greater than design preload in the affected details. The increased preload combined with the design loads could exceed the limit load capability of the joint.”
While Boeing asserts that there is no immediate safety issue, the federal document suggested that, in a worst-case scenario, the condition could cause a failure of structural integrity. In terms of the affected aircraft, the report suggested every Dreamliner with a line number of six to 687, as well as 689-873, 875-885, 889-890, 895, 896, and 897 will need to be inspected.
Aircraft line number 687 was delivered in April 2018. 895-897 were received by their airlines just over a year ago. While Boeing is keen to downplay the severity of the flaw, the raising of additional concerns with these young aircraft is bad press for the planemaker.
With the 737 MAX disaster still ringing in their ears, Boeing has a lot of work to do if it is to restore the confidence of its airline customers and the flying public.
