Definition
A condition in which ice accumulates between the electrodes of an older-style spark plug, forming a conductive path that shorts out the spark and prevents ignition of the fuel-air mixture in that cylinder. It typically occurs in cold, moist conditions when moisture condenses inside the spark plug and freezes across the gap.
Plain English
Ice forms inside a spark plug and connects the two metal points where the spark is supposed to jump. Instead of making a spark, the electricity takes the easy path through the ice, so the cylinder doesn't fire.
Context Anchor
Seen in powerplant and carburetor icing discussions, especially when troubleshooting loss of engine power in cold or humid conditions.
Derivation
Called a 'bridge' because the ice physically spans the gap between the two electrodes — like a bridge connecting two banks of a river — giving the electrical current a shortcut around the spark gap.
Why Pilots Care
Unremoved ice increases drag, reduces lift, and can lead to loss of control authority if left unaddressed.
Analogy
It is like frost building across a small screen or opening until air can no longer pass through freely.
Grounding Statement
Picture ice growing from the sides of an air opening until the gap is partly or fully covered.
Intuition Check
Do not read “bridging” as something helpful or structural here. In this term, the ice is spanning an opening and becoming a blockage.
Example Sentence 1
After a cold-soaked night on the ramp, the mechanic suspected ice bridging when one cylinder refused to fire during the morning start.
Example Sentence 2
During preflight the mechanic checked boot operation to confirm the system would not allow ice bridging in light rime conditions.