PRODUCT: Bell Helicopter Textron Canada (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). SUBJECT: Airworthiness Directive 012-12-11 ACTION: Final Rule
SUMMARY: This AD requires determining the date of STC installation, determining if the aircraft has an unfiltered turbine outlet temperature (TOT) internal over-temperature warning light, and based on those findings, installing an NVIS filter. This AD was prompted by the finding that an unfiltered 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 actions of this AD 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.