According to 46 CFR regulations pertaining to tests and inspections as related to automatic auxiliary boilers, the fuel supply control solenoids must be checked for proper shutdown operation. What must be checked for?

Correct Answer: Option D — Upon a normal cycling or safety shutdown, the fuel control solenoid valve coil under test closes with no visible leakage into the burner(s).

Fuel supply control solenoids on automatic auxiliary boilers must undergo periodic verification to ensure they close tightly during normal cycling or safety shutdowns, preventing any visible fuel leakage into the furnace and avoiding catastrophic flare-backs.