A CRJ700; AFTER TKOF; HAD MACH TRIM AND HORIZONTAL STABILIZER TRIM FAIL. FLT CREW WAS UNABLE TO RESET IT IN FLT.

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AFTER TKOF; MACH TRIM AND STAB TRIM FAILED. COMPLIED WITH APPROPRIATE CHKLISTS. CONTINUED TO ZZZ AT 250 KTS. COULD NOT REENGAGE EITHER TRIM. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE CRJ700 HAS A BUTTON ON EACH CTL YOKE THAT LOOKS LIKE A 'PUSH TO TALK' BUTTON. THIS BUTTON IS THE MACH TRIM AND STABILIZER TRIM DISCONNECT BUTTON. BUTTON; IF ACTIVATED; DISCONNECTS THESE FUNCTIONS AND CANNOT BE RESET IN THE AIR. A BULLETIN ISSUED BY THE COMPANY DESCRIBES THE DISCONNECT FUNCTION AND THE NO RESET IN THE AIR. THE RPTR DOES NOT BELIEVE THE BUTTON WAS PUSHED INADVERTENTLY BY EITHER CREW MEMBER; BUT THE MACH TRIM AND STABILIZER COULD NOT BE REENGAGED. THE RPTR HAS RECEIVED NO INFO FROM MAINT ON THE MAINT ACTION TAKEN; SO THE IDEA THE BUTTON WAS PUSHED IS ONLY A SPECULATION. THE RPTR SUGGESTED THAT IF THIS EVENT WAS CAUSED BY THE BUTTON BEING INADVERTENTLY ACTIVATED; THEN IT SHOULD HAVE A SWITCH GUARD. CALLBACK CONVERSATION WITH RPTR 665339 REVEALED THE FOLLOWING INFO: THE RPTR STATED THE MAINT ACTION TAKEN WAS NOT RPTED BUT THE AIRPLANE WAS TAKEN OUT OF SERVICE AND REMAINED OVERNIGHT. THE RPTR DESCRIBED THE FUNCTION OF THE DISCONNECT BUTTON BUT DOES NOT BELIEVE THIS WAS ACTIVATED. RPTR FEELS THAT THIS BUTTON SHOULD BE GUARDED.