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F-35 pilot held 50-minute airborne conference call with engineers before crash

(www.cnn.com)
279 points Michelangelo11 | 4 comments | 27 Aug 25 11:38 UTC | HN request time: 0.647s | source
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preisschild ◴[27 Aug 25 11:53 UTC] No.45038390[source]▶
But why was there water in the hydraulic system in the first place?
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grumpy-de-sre ◴[27 Aug 25 12:08 UTC] No.45038537[source]▶
Likely contamination of ground handling equipment [1]. Unfortunately can happen. I wonder if the hydraulic fluid is hygroscopic or something?

1. https://www.pacaf.af.mil/Portals/6/documents/3_AIB%20Report....

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4gotunameagain ◴[27 Aug 25 12:13 UTC] No.45038600[source]▶
Hydraulic brake fluid is glycol ether based and hygroscopic. Planes usually use mineral based fluids which are not, but heck if I know what the F-35 uses.
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1. grumpy-de-sre ◴[27 Aug 25 12:19 UTC] No.45038659[source]▶
Quoting ChatGPT (and after a quick sanity check),

The F-35 Joint Strike Fighter uses a specialized hydraulic fluid that’s based on a synthetic ester formulation, not a petroleum-based fluid.

Specifically, it uses phosphate ester–based fire-resistant hydraulic fluid (commonly in the MIL-PRF-83282 or newer MIL-PRF-87257 class).

Apparently the older phosphate-ester based hydraulic fluids were hygroscopic but I'm not sure if the newer variants are.

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2. yobbo ◴[27 Aug 25 12:33 UTC] No.45038765[source]▶
Sounds similar to DOT-5 brake fluid.

Maybe this: https://en.wikipedia.org/wiki/Tributyl_phosphate

"The major uses of TBP in industry are as a component of aircraft hydraulic fluid, brake fluid, and as a solvent for extraction and purification of rare-earth metals from their ores"

It might be better if it is hygroscopic as the water won't separate and risk forming ice plugs in the hydraulic lines.

3. Workaccount2 ◴[27 Aug 25 14:24 UTC] No.45040169[source]▶
Yes, lets condition people to never reveal they used ChatGPT. Even though the response seems accurate.

[1]https://hiigroupasia.com/f-35-aviation-ground-support-equipm...

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4. grumpy-de-sre ◴[27 Aug 25 14:49 UTC] No.45040502[source]▶
Yeh the sanity check involved researching the milspecs listed and the connection to the F35 program.