As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THERE ARE TWO TYPES OF WARNING HORNS. ONE MANUFACTURER IS KLAXON, THE OTHER IS VOXBELL. BOTH OF THE HORNS ARE FAILING DUE TO POOR WORKMANSHIP. ITEMS CAUSING FAILURE ARE POOR SOLDERING POINTS AND RIVETS NOT FULLY SQUEEZED WHICH SHOULD MAKE CONTACT TO ACTIVATE THE HORN WHEN ROTOR RPM FALLS BELOW MINIMUM. HAVE HAD TO ORDER FOUR HORNS IN SIXTY-DAY PERIOD.