Bomb tester

A shop tool used to test spark plugs after they have been cleaned and gapped. After a spark plug has been serviced, it is screwed into the bomb tester, and about 200-psi air pressure is applied to the firing end. High voltage is directed into the terminal cavity of the spark plug, and the electrodes are observed to see the type and amount of spark being produced. If a spark plug operates properly in a bomb tester, it will almost always work properly when it is installed in an aircraft engine.