Forum: F-16 Procedures

Will a cracked or loose hydraulic return line suck air, I have been told it would by many fellow crew chiefs, even some pro-supers, but I never believe nor have ever seen it, I trouble shoot systems that some say "must be a cracked line sucking air" I look at them and usually say there are only a few places a hyd system will induce air into itself, and usually its an accumulator, rarely ISA, and sometimes just bad mule operation. So whats everyone think.

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My view on this is,

Air gets "sucked" into a vacuum, the system operates at ~3,000 psi, it doesn't care if the fluid is coming from or going to the pump. If you have something loose enough (or cracked) to let air "in", it's going to be leaking.

Improper mule operation is/was the biggest factor in "Air in the System", and speaking from an "old school" analog flight control B-shopper, if you don't have your GPM cranked to 28 or higher flow rate you're asking for mulfunctions above "step 43". (any young guys even know what that is.... Very Happy

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The newer mules are much better than the old diesel models, the muffler on the top would be cherry red by the end of the ops checks...This was one of the reasons "b-shoppers" used to be able to get engine run qualified....don't know if they still do it or not.

Smitty

Air always seems to be in B-system doesn’t it?

Suspect JFS accumulator has fixed the ones I troubleshot. I really can’t see how back shop hydraulics can bench check a JFS accumulator due to the high volume of nitrogen involved to make the energy to spin up the JFS. If it’s in the back shop they might as well repack it.

Forum: F-16 Procedures

Sucking Air