help pettal arm keeps falling off

[adam valentine]

my entire pettal arm keeps falling off the crank even tho ive locktighted it and lock washer it why does this keep happening

 

[Goat Herder]

The arm at the square taper to bottom bracket must be deformed? This is something to check on new bikes if it is left loose and then ridden enough it goes down hill from there so to speak. Once they deform enough there not the same.

 

[scotto-]

Yes, sounds like it's time for new cranks.....sad but true.