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Beringer brakes

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by LVG2018 » Fri Dec 14, 2018 10:58 pm

Beringer brake label warns “Mineral oil only.” Several builders advised that standard 5606 works just fine. Still, others warn about ignoring manufacturer recommendations. I’m ready to finalize brake set-up and undecided which way to turn. Can anyone offer more than an unsupported opinion?
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Joined: Mon Apr 09, 2018 1:25 am
Location: Hemet

by dcroson » Fri Jan 25, 2019 4:25 am

You definitely want to use a mineral oil based product, and not a DOT4 type of fluid. As far as the 5606, below is what I found online at http://www.groveaircraft.com/fluid.html (and other sites had similar info):

Hydraulic Fluids

All Grove brake systems incorporate Buna-N (Nitrile) O-Ring seals that are compatible with MIL-H-5606 hydraulic fluid which has been the aircraft industry standard for many years.

MIL-H-5606 hydraulic is a mineral-oil based fluid with excellent operating properties over a temperature range of -65°F to 274°F. A major deficiency of MIL-H-5606 is its high degree of flammability. Because of this, the commercial aircraft industry has developed and uses hydraulic systems based on phosphate-ester based hydraulic fluids. However, these fluids ARE NOT compatible with MIL-H-5606 or its systems.

The military led the way in developing a more flame resistant hydraulic fluid that is compatible and miscible with MIL-H-5606. As a result, a synthetic-hydrocarbon based fluid MIL-H-83282 (now MIL-PRF-83282) was developed which is superior to MIL-H-5606 (now MIL-PRF-5606) in fire resistant properties, but lacks good qualities in low temperature viscosity.

More recently MIL-PRF 87257 was introduced in order to address the concerns over the low temperature viscosity weakness of MIL-PRF-83282.

Bottom Line: MIL-H-5606 has been replaced with MIL-PRF-83282 and MIL-PRF-87257. Each of these fluids, and their associated systems, are compatible and miscible with each other. You can mix any combination and/or amount of these fluids together without any ill effects.

If, and/or when, you change over from MIL-H-5606 you can either:
1. drain your hydraulic system and refill with MIL-PRF-83282 or MIL-PRF-87257, or
2. merely top off the reservoir with MIL-PRF-83282 or MIL-PRF-87257 as needed.
Both methods have been used with great success with no reported problems.
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Joined: Tue Jun 05, 2018 4:54 pm
Location: Lake Mary

by larry fish » Thu Jan 31, 2019 3:15 am

I used the 5606 and it made the O-rings in the master cylinders swell up and the pistons sized up. I also had to replace the O-rings in the calipers
larry fish
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Joined: Sun Jan 30, 2011 3:52 am

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