What kind of liquid can be seen 'leaking' from the upper surface of the wing of a Boeing 737-800?xIiJh0l1 ରପisnତFfJ Cy EelEh50dY HSsKx YW128ew
Can anyone advise what the liquid seen on the wing of a 737-800 on approach as highlighted on the attached images is? The liquid was seen "pulsating" from the bases marked by the arrows. As the plane came to land, the intensity of the flow decreased until it eventually stopped altogether.
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1$\\begingroup$ Lubricant, rain, melting ice.... Any liquid will vibrate when blasted with high winds. $\\endgroup$ – Carey Gregory 12 hours ago
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$\\begingroup$ Not exactly sure what you mean by Any liquid will vibrate when blasted with high winds. That liquid was throbbing from the edges that I marked so whatever this was, it came from within the wing so it's unlikely to be either ice. The conditions were dry and hot, so not conducing to ice formation. $\\endgroup$ – VH-NZZ 12 hours ago
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1$\\begingroup$ You said it was pulsating. I meant the same by saying "vibrate." I simply meant that any liquid is going to pulsate/throb/vibrate in a strong wind. My guess would be it's lubricant but who knows? Small amounts of water can get inside a wing easily. $\\endgroup$ – Carey Gregory 12 hours ago
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$\\begingroup$ And leak out of the edges? The aircraft was in steady descent at a seemingly constant rate, and in smooth air. $\\endgroup$ – VH-NZZ 11 hours ago
1 Answer
The pictures show water condensation on the wing upper surface due to very cold fuel in main tank number 2.
The fuel is cold because the air temperature at cruise altitude is significantly colder than the air temperature encountered during the descent.
The condensation appears to be oozing from the wing but it is in fact flowing slowly over the surface, filling and overflowing every seam and imperfection.
Since you have provided photos and not a movie, I can't tell you what the "pulsating" really was, but it probably was either a slight boundary layer turbulence, or changes in the seam geometry due to wing flexing.
