Prevost XLII Skin Delamination Repair

[Hisham Amaral]

(11-08-2014 12:11)CC_Guy Wrote:  The re-glue process was Prevost's first fix. According to some, that approach failed, at least it did on some number of repairs. Then came the rivet approach that also required a change in adhesive. As I understand it, this approach too has failed. I don't know what the number of failures where after either fix and whether they were the result of workmanship in the repairs or actual failures of the adhesive or were do to some other issue. These could be isolated cases that can be explained. I just don't know, so I only throw this out as information I've heard.

With the advancements in adhesives and the fact that similar bonding has been done in other industries, it's hard to understand why this failure has occurred and why it has affected several model years. To suggest why the failures have occurred would simply be speculation on my part. What I find disturbing is that I have never heard of a single XL-II owner ever being notified by Prevost or their converter that they should have their coach tested for delamination. Not notifying owners, if that is in fact true, has to be a move now regretted. Unexpected failures or other defects happen. How you handle them is critical. Touting a million mile chassis and not notifying owners with far less than a million miles has to have a negative effect on new sales and certainly resale.

BTW, Prevost initially tested glued on panels with the passenger door on late model XLs. I've never heard of a single one of them failing (knock on wood). So, adhesives can work.

(11-10-2014 21:03)travelite Wrote:  My thoughts exactly CC_Guy. It's virtually a clean break on the panel side. This would lead me to believe that an incompatible glue was selected, or the surface preparation was defective, or the process setup times weren't followed, as opposed to an inadequate shear or tension strength of the adhesive itself. Sounds like this issue could be remedied.

I don't think thermal expansion of the stainless panels is much of an issue. A quick check shows expansion at 0.0000096 in/in deg F. Assuming the panels are around 100" long. That would be about 0.01" of expansion for every 10 deg F increase in temp. A 100 deg F temperature swing only results in 0.1" expansion. You can reason along these same lines and conclude that bus chassis flex isn't the issue either.


I calculate that each panel should weigh less than 100lbs which puts very little shear stress on the adhesive. Here's some specs on Loctite 5590 which give a shear yield stress of 290 psi.

Hi Arctic Bird, It doesn't take long for rust to form when salt road spray is flowing behind your panels. I looked at a coach that was parked at the beach and the internal basement beams were a mess. There was a panel leak that allowed corrosive water to flow into the basement.

David
In my opinion the issue is both manufacturing and engineering. With failure numbers that high process cannot be the only botched up job Engineering is also a large contributor. BTW each panel is 96in by 32in by I think .06IN with mass density of .283 LB/CUIN that is about 52 lbs for each panel, if the the thickness of the material is .060 in.