As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ELBOW P/N AN915-1D WAS INSTALLED IN THE OIL PRESSURE/HOBBS SWITCH SYSTEM OFF THE BACK OF THE ACCESSORY CASE. THE INSTALLATION OF THE HOBBS PRESSURE SWITCH WAS NOT DONE IAW THE MANUFACTURERS IPC. THE SWITCHES WERE NOT INSTALLED AND SUPPORTED CORRECTLY. AFTER TIME AND ENGINE VIBRATION, THE FITTING BROKE CAUSING ALL THE ENGINE OIL TO BE PUMPED OUT.