As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
TRIPLE TACH FAILED DURING START UP. NR FAILED TO SYNC, THEN WOULD DROP TO 0. AFTER SEVERAL SECONDS IT WOULD MATCH TO N2 AND THEN REVERT BACK TO ZERO. HAPPENED CONSISTENTLY 4 TIMES. REMOVED AND REPLACED SPEED PICK-UP SENSOR IAW AMM 62-41-00, 4-1. T/P MOC GOOD.