As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
When A/C taxied to the gate position, tower informed smoke is observed from R/H ENG site and then cabin crew reported HYD ordor is smelled in the cabin. Captain shutdown the APU and related symptom disappeared and then L/H HYD QTY indicated 7 QT remained. Mechanics inspected and found one L/H HYD Tube B nut loose. Retighten and running test all symptom is no long observed.