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I noticed some dots and lines on the Boeing 747 engine pylons. What are they?
The above image is as seen in this video at 2:18.
These are latches holding the engine support pylon panel in closed. Behind this panel is the diagonal brace.
This area was modified ~1992 due to the El Al Flight 1862 and China Airlines Flight 358 crashes.
See FAA Lessons Learned (via archive.is).
Required, but never shown