Airworthiness Directives; Pilatus Aircraft LTD Models PC-12 and PC-12/45 Airplanes

This amendment supersedes Airworthiness Directive (AD) 99-17- 08, which currently requires modifying the generator 2 excitation by removing certain diodes and installing a new 5-amp circuit breaker and suppression filter on certain Pilatus Aircraft Ltd. (Pilatus) Models PC-12 and PC-12/45 airplanes. This AD is the result of the Federal Aviation Administration's determination that the A250 voltage spike suppression filter in the modification kit can cause the circuit breaker 235 to trip because of overload. In extreme circumstances, this can lead to overheating of wiring. This AD requires you to modify the generator 2 excitation by removing certain diodes and installing a new 5-amp circuit breaker and suppression filter of improved design in accordance with revised procedures. This AD is the result of mandatory continuing airworthiness information (MCAI) issued by the airworthiness authority for Switzerland. The actions specified by this AD are intended to prevent damage to electrical components if generator 2 is not switched off before engine shutdown and it overheats. This could result in loss of electrical power to certain critical airplane components.