Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

MIL-H-5605 vs MIL-PRF-83282

MIL-H-5605 vs MIL-PRF-83282

MIL-H-5605 vs MIL-PRF-83282


As reported in various literature and from your conversion above, both MIL-STD Hydraulic are compatible and miscible, and that 83282 is designed to replace 5606. I'm looking at replacing the MIL-H-5606D on the Helicopter type that i work on, with MIL-PRF-83282, because somehow, that Helicopter uses both types of hydraulic. Weird..anyway, to effect the change, i can either drain the existing MIL-H-5606 and flush the system to purge out all existing MIL-H-5606, or i can just top up the existing MIL-H-5605 with MIL-PRF-83282. For the latter, i read that when you mix the two, there is a reduction of the fire-resistant properties of the now-mixed hydraulic fluid. Question is, is there a unit of measure of fire-resistant property? Is fire-resistant property, the same as flammability?

Thanks in advance for your answers!



RE: MIL-H-5605 vs MIL-PRF-83282

As I recall one of the principle reasons for the development of MIL-PRF-83282 was because they needed a fluid that unlike 5606 wasn't flammable. Changing the fluid from 5606 to 83282 is a modification that will require approval.

If the helicopter uses both, there is a specific reason and until that reason is determined reliably one shouldn't progress any farther (this is one of those apparently really simple modifications that's going to suck up at least a month of an engineers life).

RE: MIL-H-5605 vs MIL-PRF-83282

Ethan... verymadmac has provided very valuable precautionary advice. Proceed with great CAUTION!

This 'modification' could entail a significant flight test program also.

Low and high temp properties of oils can vary a lot.

Most applicable seal rubbers are highly compatible with hydrocarbon base and synthetic hydrocarbon base oils.

My acft replaced all MIL-PRF-5606 hydraulic oil with MIL-PRF-87257 [lower service temp capable oil] on an attrition basis starting a long time ago. This was done with a lot of prior lab analysis, formal flight test [drain 100% OR mix-in with attrition] and in-service testing with a few designated acft.

NOTE/odd info.

One of our FMS operators did NOT transition to 87257 and has continued to use 5606... for their 'own confidential reasons'.

Oil that has been in-service many years may and has accumulated wear and moisture contaminates... in a 'small system'... may easily justify 100% drain/replace.

Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close