Narrative:

After takeoff; mach trim and stabilizer trim failed. Complied with appropriate checklists. Continued to ZZZ at 250 KTS. Could not reengage either trim. Callback conversation with reporter revealed the following information: the reporter stated the CRJ700 has a button on each control 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 reporter does not believe the button was pushed inadvertently by either crew member; but the mach trim and stabilizer could not be reengaged. The reporter has received no information from maintenance on the maintenance action taken; so the idea the button was pushed is only a speculation. The reporter suggested that if this event was caused by the button being inadvertently activated; then it should have a switch guard. Callback conversation with reporter 665339 revealed the following information: the reporter stated the maintenance action taken was not reported but the airplane was taken out of service and remained overnight. The reporter described the function of the disconnect button but does not believe this was activated. Reporter feels that this button should be guarded.

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Original NASA ASRS Text

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

Narrative: 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.

Data retrieved from NASA's ASRS site as of January 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.