As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE REMOVING LT MAGNETO FOR TBO, THE NR 4 CYLINDER INTAKE PIPE HAD TO BE REMOVED FOR ACCESS TO THE MAGNETO. REMOVAL OF THE INTAKE PIPE REVEALED THAT THE INTAKE PIPE HAD A CRACK IN THE FLARE END THAT IS SECURED TO THE CYLINDER INTAKE PORT. FURTHER INVESTIGATION REVEALED THAT THE NR 4 INTAKE PIPE WAS THE ONLY PIPE FOUND IN THIS CONDITION. THIS ENGINE HAD AN INTERMITTENT PROBLEM OF RUNNING ROUGH FOR A FEW MOMENTS THEN BACK TO RUNNING NORMALLY. ALL IO-550P OPERATORS SHOULD BE MADE AWARE OF THIS PROBLEM.