←back to thread

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

(www.cnn.com)
291 points Michelangelo11 | 2 comments | 27 Aug 25 11:38 UTC | HN request time: 0.468s | source
Show context
potato3732842 ◴[27 Aug 25 14:59 UTC] No.45040631[source]▶
Everyone in these comments making quips about software is missing the elephant in the room, where the heck did that water in the hydraulic system come from? Pretty much any hydraulic fluid for outdoor use will suck up a lot of water so as to prevent situations like this so this clearly isn't a teaspoon or even cups of condensation problem.
replies(1): >>45043954 #
foxyv ◴[27 Aug 25 19:28 UTC] No.45043954[source]▶
Hydraulic fluid is very hydroscopic. It will happily suck the moisture out of the air if it is exposed long enough. This is why you don't use half empty bottles of brake fluid. I suspect that the fluid was left in opened containers for too long before being installed in the jet, allowing it to load up on water.
replies(1): >>45045066 #
1. potato3732842 ◴[27 Aug 25 20:49 UTC] No.45045066[source]▶
You are massively mixing things up.

Water boils/evaporates off from oil based fluids in normal operation. Hydraulic fluid additives don't suck up water like brake fluid, they just mix with it if present, and they can't mix with all that much. If these first two things weren't true it would have huge implications for the design of all sorts of things. If hydraulic fluid could mix with a lot of water we wouldn't be reading this story.

I assume these jets use skydrol. I'm only casually familiar with it but unaware of it having special water related properties that differ from normal petroleum products.

Glycols are a different story.

replies(1): >>45046471 #
2. foxyv ◴[27 Aug 25 23:16 UTC] No.45046471[source]▶
They use MIL-PRD-83282. It can become contaminated with water, either from the air or condensation. Typically it is tested before being placed in an aircraft and it can be purified if particle or water content is too high.

https://www.pall.com/content/dam/pall/aerospace-defense/lite...