×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

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!
  • Students Click Here

*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

Jobs

Refinishing the seating of a fillet panel with PR1440 being applied over an old (damaged) sealant?

Refinishing the seating of a fillet panel with PR1440 being applied over an old (damaged) sealant?

Refinishing the seating of a fillet panel with PR1440 being applied over an old (damaged) sealant?

(OP)
During the refinishing of exterior of the A/C, after PDM (Major overhaul), damaged sealant on the seating of fillet panels was required to be refinished.… From past experience and as a standard practice, old sealant was required to be completely removed first and then new one was applied, since old and new layers, being long chain polymers, won’t stick……

Recently I heard about another procedure to degrease the old sealant with MEK or PD680, scuff it and apply a fresh coat………..

Did anybody experience this practice in the past? Or knows of any justification? Or any technical answers for this?

thanx

RE: Refinishing the seating of a fillet panel with PR1440 being applied over an old (damaged) sealant?

You do not give enough information to answer the question.
If the sealant is a silicone then the answer is no, you cannot do that, you have to take it all off.
If the sealant is a polyurethane then you MIGHT be able to what you are asking.
More details of the type of sealant and/or the aircraft will get you a better answer.
B.E.

The good engineer does not need to memorize every formula; he just needs to know where he can find them when he needs them. Old professor

RE: Refinishing the seating of a fillet panel with PR1440 being applied over an old (damaged) sealant?

I am sorry ,I should have said"Existing sealant" Poly sulphides do not stick to silicone.
B.E.

The good engineer does not need to memorize every formula; he just needs to know where he can find them when he needs them. Old professor

RE: Refinishing the seating of a fillet panel with PR1440 being applied over an old (damaged) sealant?

(OP)
Berkshire!
sorry for not quoting the sealant. Old one is PR1422, where as the new one is PR-1440.

RE: Refinishing the seating of a fillet panel with PR1440 being applied over an old (damaged) sealant?

Ok so this is the old PRC loved and hated by mechanics everywhere.
I think you are going to have to get it off, Scrape as much as you can, use an acrylic scraper, then use MEK to clean off the the rest.
Methylene Cloride will also remove it.
The solvents break the polymer chains, making the PRC swell and wrinkle.
I would not put new over old if you have used solvent.
B.E.

The good engineer does not need to memorize every formula; he just needs to know where he can find them when he needs them. Old professor

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!


Resources