"P" Trap under bath tub
 

I have a '94 Classic 22 foot and the bath tub/shower drains very slowly. It has done this since new and I want to remove the "P" trap from under the trailer. Does anyone know if tis trap is screwed on like under a house sink or glued in place like most pvc/abs piping. Can not see trap as it has a metal cover over it.

Thanks for every ones help in advance.

If you go to this thread, there is a photo with the tub removed. It's just like the ones in a house.

https://www.hilotrailerforum.com/f27/...nder-tub-5916/

Bath plumbing
 

I have a 1990 229L and right now I am working in the bathroom redoing the vinyl wall covering. I have the panel remove from the side of the tub ( to recover it) and all the plumbing is exposed. Yes, the trap and drain for the tub are standard house plumbing and are threaded. Looks like it would be easier to remove the 4 screws from this panel and pull it out at the bottom and remove this panel and unscrew the trap.

Air vent
 

Be sure that your grey water is vented properly in that bath room. I noticed some problems with my 24 footer if I wasn't parked perfectly level. To fix this I added a "T" ( tee) to the line and put a " cheater vent" in the horizontal line and glued an 1 1/2" fpt adapter it in the top of the Tee. It runs much better now, even on level ground.


Also, Hair seems to collect around pop-ups or anything it can hang on to. Its worth checking in all the way thru in my opinion.

I bought this vent from home depot, Oatey 1-1/2 in. ABS PTC In-Line Cheater Vent mod#39012
It's safe for rv use and allows some air to enter making it easier for water to drain. I left the old vent attached but its really not needed.
Good luck,
Dave

Most likely screwed.
Remove the panel which is held on with 4 or 6 white phillips head screws and you have a tight access to the underside.
First try to run wire down the drain to pick out the hair that is likely causing the clog.