https://cimg4.ibsrv.net/gimg/www.fly...d73f0e092d.jpg
Not particularly paint related but noticed this on the wing of a recent flight. Having been a auto mechanic in a prior life, I know dirt is usually attracted to oil/fluid which was somewhat disconcerning. The dirt patched didnt grow throughout the flight, and I assumed any leak would have set off a low/abnormal pressure indicator so maybe it was leftover from a prior leak?

To my inexpert eye, the smudges appear to start at the leading edge, which would imply the cause is (was?) external to the wing. It slightly difficult to interpret, but the accumulation further back is likely resulting from vortices generated at the panel seam.

edit: good answer below.

The black marks come from metal rubbing against metal in a moist environment, i.e. clouds or rain. They are extended back from the area of each set of slat tracks.

This is one way that mechanics identify rivets that are a bit loose. The slight movement that they allow produces those black streaks.

N791UA looking a bit tired:

poor bird. Last made it to VCV in November 2011 for a new paint job.

As of January 4, 2021, N791UA still looks like the worst failed paint in the whole airline (unless there are examples I haven't seen).

https://www.jetphotos.com/photo/10013139

Hoping another visit to VCV will come soon!

Who knew that VCV would be so apeeling for UA A/C?

David

I would appeal for correct spelling, but I now see what you're up to. :eek:

Not sure if it counts but one of the CRJ700s (seem to recall it's one of the Mesa birds in the N5xxLR registration series always seems to be parked on one of the even D gates at IAD and just as universally seems to be missing more paint each time. Is this UA's new fleet reduction strategy? Whichever UAex bird voluntarily drops it's entirely livery first gets voted out of the fleet?

Probably this one :) N506MJ

Yep that. Looks like it :-) (or should that really be :-( )

If you've seen the sad CR7 in question recently IAD, I think there must be a second one in such a sorry state. N506MJ has been parked for a bit. https://sites.google.com/site/united...fleet-tracking (last flight 4-Jan going OKC - TUS storage)

I've shot this N506MJ on December 28th. Haven't seen in January another bird looking like that at IAD.

I definitely saw it in December -- haven't really been in IAD during daylight hours in January -- though oddly I'm typing this from SFO waiting for 1491 to IAD so...if there is an imposter maybe I'll see it :)