In an engine ground check, if the ignition switch is moved from BOTH to either LEFT or RIGHT, what is a normal indication?

When switching the ignition switch from BOTH to either LEFT or RIGHT during an engine ground check, a slight drop in RPM is expected. This occurs because, in the BOTH position, both ignition systems are operational, providing maximum spark energy for combustion. When the switch is moved to LEFT or RIGHT, one of the ignition systems is momentarily removed from the circuit, which can cause a slight decrease in engine speed due to the reduction in available spark energy.

This slight drop indicates that the remaining operational ignition system is still capable of keeping the engine running; however, the change reflects the loss of the second ignition source. Normally, a significant RPM drop or engine shutdown would indicate a malfunction in the ignition system, which is not the expected behavior when the switch is correctly transitioned to either LEFT or RIGHT.

Option choices that suggest a large drop in RPM, momentary interruption of both ignition systems, or complete engine shutdown indicate failure conditions that are not typical during a standard ground check of a properly functioning engine.