Silsbee, F. B., Loeb, L. B., Sawyer, L. G., Fonseca, E. L, Dickinson, H. C., Agnew, P. G.
The successful operation of the spark plug depends to a large extent on the gas tightness of the plug. Part 1 of this report describes the method used for measuring the gas tightness of aviation spark plugs. Part 2 describes the methods used in testing the electrical conductivity of the insulation material when hot. Part 3 describes the testing of the cold dielectric strength of the insulation material, the resistance to mechanical shock, and the final engine test.
An Adobe Acrobat (PDF) file of the entire report: