Honesty is the only policy.
I have a failed CFI checkride and a failed Dash-8 upgrade checkride in my history. Also a taxiway excursion in a blizzard (I was found not at fault) by the FAA. It's all listed on my Airlineapps file.
I suspect it's holding me back from getting a call but like the other guys said, they're gonna find out about it anyway. When they do, if you didn't disclose it, kiss your butt goodbye. Disclose it.
K