As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WITH APU PRESSURIZING PACKS, DUCT PRESSURE FLUCTUATES FROM 10 TO 35 PSI. GROUNDED - YES. ACCOMPLISHED ENG NORMAL START REF AMM 71-00-00 WITH APU BLEED AIR WITH NO FLUCTUATION NOTED APU OPS NORMAL THIS CLEAR MEL 49-52-01B SEA MOC NOTIFIED PLACARDS REMOVED.