As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SMF FLIGHT NR 2302: LOUD HUM WITH PTU AND STANDBY PUMP ACTIVATED. ALL PRESSURE GOOD. AIRCRAFT RETURNED TO BLOCK. MAINTENANCE C/W Q400 AMM TASK 29-11-36-710-801 AND TASK 29-11-61-710-801. ALL TESTS NORMAL WITH NO DEFECTS NOTED. NO PARTS REPLACED. AIRCRAFT RETURNED TO SERVICE.