Crj-700 flight crew experiences ahrs heading anomalies departing dfw resulting in a track deviation ...

Narrative:

While climbing on the dartz 1 RNAV departure after crossing owlls; I noticed the autopilot initiated a late turn and as a result we were of course to the north. The captain noticed that both of our dg's [directional gyros] had turned nearly 90 degrees from where they should be. Within seconds; ATC advised us that we were off course and asked us to fly a heading. We advised him that we were having navigation issues and we were flying by the standby compass. I switched the autopilot from navigation mode to heading mode to fly the assigned heading by the compass. I flew the plane and handled the radios; while the captain consulted the QRH. Just as the captain was troubleshooting the ahrs comp mon issue the autopilot initiated a turn to the right. Immediately; we took it out of heading mode and let the airplane fly in roll mode to continue on the assigned heading. After complying with the EFIS comp mon QRH procedure; we were able to establish a normal operating system where both dg's matched the standby compass. We advised ATC that our navigation system was operational. We accepted a clearance direct to an enroute fix. We asked ATC to advise us of any course or heading abnormalities which they may notice while enroute. When ATC handed us off to the next facility; they advised us that no abnormalities were observed. Upon landing; the captain entered the discrepancy into the maintenance log. Failure of the ahrs system to provide accurate information despite execution of the SOP.

Original NASA ASRS Text

Title: CRJ-700 flight crew experiences AHRS heading anomalies departing DFW resulting in a track deviation on an RNAV departure. ATC issues headings and the system is returned to normal operation a few minutes later.

Narrative: While climbing on the DARTZ 1 RNAV DEPARTURE after crossing OWLLS; I noticed the autopilot initiated a late turn and as a result we were of course to the north. The Captain noticed that both of our DG's [Directional Gyros] had turned nearly 90 degrees from where they should be. Within seconds; ATC advised us that we were off course and asked us to fly a heading. We advised him that we were having navigation issues and we were flying by the standby compass. I switched the autopilot from NAV Mode to Heading Mode to fly the assigned heading by the compass. I flew the plane and handled the radios; while the Captain consulted the QRH. Just as the Captain was troubleshooting the AHRS Comp Mon issue the autopilot initiated a turn to the right. Immediately; we took it out of heading mode and let the airplane fly in Roll Mode to continue on the assigned heading. After complying with the EFIS COMP Mon QRH procedure; we were able to establish a normal operating system where both DG's matched the standby compass. We advised ATC that our navigation system was operational. We accepted a clearance direct to an enroute fix. We asked ATC to advise us of any course or heading abnormalities which they may notice while enroute. When ATC handed us off to the next facility; they advised us that no abnormalities were observed. Upon landing; the Captain entered the discrepancy into the maintenance log. Failure of the AHRS system to provide accurate information despite execution of the SOP.

Data retrieved from NASA's ASRS site 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.

Attributes
ACN	1171668
Time
Date	201405
Local Time Of Day	1201-1800
Place
Locale Reference	D10.TRACON
State Reference	TX
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Regional Jet 700 ER/LR (CRJ700)
Operating Under FAR Part	Part 121
Flight Phase	Climb
Route In Use	SID DARTZ1
Flight Plan	IFR
Component
Aircraft Component	AHRS/ND
Person 1
Function	First Officer Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Person 2
Function	Pilot Not Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy Deviation - Track / Heading All Types

Crj-700 flight crew experiences ahrs heading anomalies departing dfw resulting in a track deviation on an RNAV departure. ATC issues headings and the system is returned to normal operation a few minutes later.