Examination of Aircraft Warning and Caution Lights After Shock Testing.

摘要

Warning and caution light bulbs recovered after aircraft accidents provide useful information. It is generally assumed that upon impact the filament of an unlit bulb will break without deformation, whereas a hot filament will show extensive elongation. Deviations from the idealized behavior were investigated by shock tests on F-16 warning and caution light bulbs and included in the report. From the tests it was concluded that relatively new lamps do not show the idealized behavior described above. This makes it necessary in certain cases to estimate the number of burning hours by a simple Scanning Electron Microscopy investigation of the surface morphology of the filament. Besides its age, the behavior of a filament upon impact is also influenced by the direction and especially the duration and maximum g-level of the impact. However, the behavior of a burning lamp is not influenced by deviations from the correct voltage. The above results are included in a recommended procedure for examining light bulbs after aircraft accidents.