What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
When arrived at the aircraft their was a heading mismatch message on the PFD, after push the message was still there with both headings showing off, crew contacted maintenance control and performed a circuit breaker reset. Once this was completed the system aligned and was correct for both pilots, crew continued to taxi to the runway for departure. Departing off runway 31 in lga, crew lined up the runway and confirmed runway 31 and everything looked correct, once in the air crew commenced a turn to 020, the aircraft was showing 020 on the heading, tower advised to fly heading 020. Tower then said that they were showing 60 degrees off that heading. We then tried another turn to a different heading and same thing. Crew tried to navigate using the FMS with command heading, it was the same. It had seemed to have lost its place in space, it was also showing weird wind read outs like 190 knots at 8000 feet, this is when ATC declared a emergency requested to return to lga visually as it was day VFR. ATC provided no gyro headings for for a visual approach onto runway 31. We landed on runway 31 with no issue and returned to gate.
After several hdg issues with the Q400 in lga, the cause of the incidents is magnetic interference of the right-hand flux valve by fuel distribution pipes in the ground. Coordinating not parking the Q400 at this gate and will issue an ofp NOTAM. The gate in question is 53.
As the FAA filed it
WHEN ARRIVED AT THE AIRCRAFT THEIR WAS A HEADING MISMATCH MESSAGE ON THE PFD, AFTER PUSH THE MESSAGE WAS STILL THERE WITH BOTH HEADINGS SHOWING OFF, CREW CONTACTED MAINTENANCE CONTROL AND PERFORMED A CIRCUIT BREAKER RESET. ONCE THIS WAS COMPLETED THE SYSTEM ALIGNED AND WAS CORRECT FOR BOTH PILOTS, CREW CONTINUED TO TAXI TO THE RUNWAY FOR DEPARTURE. DEPARTING OFF RUNWAY 31 IN LGA, CREW LINED UP THE RUNWAY AND CONFIRMED RUNWAY 31 AND EVERYTHING LOOKED CORRECT, ONCE IN THE AIR CREW COMMENCED A TURN TO 020, THE AIRCRAFT WAS SHOWING 020 ON THE HEADING, TOWER ADVISED TO FLY HEADING 020. TOWER THEN SAID THAT THEY WERE SHOWING 60 DEGREES OFF THAT HEADING. WE THEN TRIED ANOTHER TURN TO A DIFFERENT HEADING AND SAME THING. CREW TRIED TO NAVIGATE USING THE FMS WITH COMMAND HEADING, IT WAS THE SAME. IT HAD SEEMED TO HAVE LOST ITS PLACE IN SPACE, IT WAS ALSO SHOWING WEIRD WIND READ OUTS LIKE 190 KNOTS AT 8000 FEET, THIS IS WHEN ATC DECLARED A EMERGENCY REQUESTED TO RETURN TO LGA VISUALLY AS IT WAS DAY VFR. ATC PROVIDED NO GYRO HEADINGS FOR FOR A VISUAL APPROACH ONTO RUNWAY 31. WE LANDED ON RUNWAY 31 WITH NO ISSUE AND RETURNED TO GATE.
AFTER SEVERAL HDG ISSUES WITH THE Q400 IN LGA, THE CAUSE OF THE INCIDENTS IS MAGNETIC INTERFERENCE OF THE RIGHT-HAND FLUX VALVE BY FUEL DISTRIBUTION PIPES IN THE GROUND. COORDINATING NOT PARKING THE Q400 AT THIS GATE AND WILL ISSUE AN OFP NOTAM. THE GATE IN QUESTION IS 53.