Serious question, how do you handle the new composite sealant on the 787 nacelle panels?

I was doing a routine panel check last week and realized I'd been applying the new BMS 5-95 sealant wrong for months. The tech data sheet says to mix for 45 seconds, but I was just doing a quick 20-second stir like the old stuff. A lead at our Seattle hangar pointed out my seams were curing with tiny air pockets, which you could only see under a bright light. That could lead to moisture getting in over time. I had to redo three panels from a job two days prior. Has anyone else run into this with the newer materials and found a better mixing method?

4 comments

4 Comments

the_lee7d ago

That BMS 5-95 is way more sensitive to mix time than the old stuff. Those micro-bubbles can definitely go deep enough to cause a leak path.

lee8477d ago

Honestly, that sounds like a paperwork problem more than a real one. Those tiny bubbles probably don't go deep enough to matter for a cabin pressure seal. I'd only rework it if the inspector made a fuss.

charles_mitchell7d ago

Paperwork problem" is how you end up with a story on the news. Those seals are tiny for a reason, and bubbles mean it's not right. I'd fix it now before it becomes a much bigger headache.

jakejones5d ago

Oh man, don't get me started on paperwork problems. My own garage door opener has a "temporary" fix from 2018 that I keep meaning to properly document. It's holding, but I know that's exactly how these stories start.