Summary
We propose to adopt a new airworthiness directive (AD) for the Bell Model 206, 206A, 206A-1, 206B, 206B-1, 206L, 206L-1, 206L-3, and 206L-4 helicopters with Aviation Specialties Unlimited Inc. (ASU) Night Vision Imaging System (NVIS) lighting modified by Supplemental Type Certificate SR01383SE (STC). This proposed AD is prompted by the finding that an unfiltered turbine outlet temperature (TOT) indicator over-temperature warning light, when illuminated, created glare and reflections that could degrade the pilot's view while using night vision goggles thereby creating an unsafe condition. The proposed actions are intended to modify any unfiltered TOT indicator unit over- temperature warning light by installing a filter to prevent degradation of the pilot's vision while using night vision goggles and to prevent subsequent loss of control of the helicopter.