As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) WHEN PILOT PERFORMED THE HYDRAULIC ACCUMULATOR TEST THE HORN MALFUNCTIONED. THEN CARRIED OUT THE PRESSURE ISOLATION CHECK ( NO HORN WHEN HYDRAULICS SWITCHED BACK ON). ALL TEST WERE PERFORMED AGAIN AND HORN WAS NOT FUNCTIONING. SWITCH ON PILOT COLLECTIVE WAS CHANGED AND AIRCRAFT WAS TESTED SERVICABLE AND RETURNED TO SERVICE.