George Werber

THE SCENARIO I witnessed at my local Westford, MA flying field was one I myself have experienced all too frequently. Watching a frustrated fellow member of the 495th Flying Club struggling to keep his engine running with a bad glow plug, I found myself puzzled, as so often in the past, about why glow plugs fail. The sequence of events defeating my fellow flier's efforts to get airborne was fairly usual for a much-used plug. With the battery connected, the engine would run fine, and the idle was good. Then, despite its properly tuned needle valve adjustment, the engine began to run ragged once the battery was removed-and would quit completely when an idle was attempted. After this was repeated five or six times with equally futile results, someone suggested he try a new plug. Eureka! When the battery was disconnected, the engine didn't die.