Engine ignition faults, and a new method of diagnosis and location during running

This paper describes a new method of diagnosing and locating ignition faults in internal-combustion engines. Hitherto in many cases this could be effected only by the dismantling and individual inspection of the various components. The process is especially laborious and lengthy in most aircraft and tank engines, as they are equipped with screened ignition systems feeding a large number of sparking plugs, many of which are very inaccessible. In the new method, by connecting only to the primary circuit of the ignition system and by tapping off a negligible quantity of energy from one sparking plug, the performance of the ignition system under engine operation can be studied pictorially by viewing a row of stationary figures on the screen of a small cathode-ray tube. Each figure corresponds to the firing of a plug, and the figures appear on the screen in the firing order. Thus a plug can be located immediately by the position of its corresponding figure in the series. The figures undergo characteristic variations in shape according to the type of fault developed.