AD/PC-12/16 - Electrical Power - Generator No. 2 Excitation

Overview

The Civil Aviation Regulations 1998, enacted by the Commonwealth of Australia, establish a comprehensive framework for ensuring the safety and efficiency of civil aviation within the country. This legislative instrument includes the Schedule of Airworthiness Directives, which addresses specific safety concerns related to aircraft operations. One such directive, AD/PC-12/16, pertains to the Pilatus PC-12 series aeroplanes, requiring modifications to the electrical power system to prevent potential damage due to voltage spikes caused by electrical feedback from the Generator No 2 field excitation during engine shut-down. This directive was introduced to address a specific problem identified in certain models of the Pilatus PC-12, aiming to ensure the continued airworthiness of these aircraft by mitigating the risk of electrical component damage. The policy objective is to maintain high safety standards in civil aviation by proactively addressing and rectifying potential hazards identified in aircraft systems.

Scope and Application

The Civil Aviation Regulations 1998, under Part 39 - 105, specifically address the airworthiness directives for Pilatus PC-12 Series Aeroplanes, particularly through AD/PC-12/16 concerning Electrical Power - Generator No. 2 Excitation. This directive applies to all Model PC-12 and PC-12/45 aircraft with Manufacturers Serial Numbers (MSN) ranging from 101 up to and including 260. The requirement set forth by this directive is to modify the electrical power system in accordance with the Pilatus PC-12 Service Bulletin (SB) No 24-012 dated 19 February 1999, which references FOCA Switzerland AD HB 99-143. The modifications involve the removal of specific diodes and the installation of a new circuit breaker and suppression filter to prevent voltage spikes and potential overheating damage during engine shut-down. Compliance mandates that for aeroplanes with certain generator part numbers, the modifications must be completed within a specified timeframe post the directive's effective date of 25 February 1999. This legislative instrument thus ensures the safety and operational integrity of specified Pilatus PC-12 aircraft within Australian jurisdiction.

Key Provisions

The Civil Aviation Regulations 1998, specifically Part 39 - 105, mandates an Airworthiness Directive (AD/PC-12/16) for all Pilatus PC-12 and PC-12/45 series aeroplanes with Manufacturers Serial Numbers (MSN) ranging from 101 to 260. This directive (section 1) requires the modification of the electrical power system as outlined in Pilatus PC-12 Service Bulletin (SB) No 24-012 dated 19 February 1999. The modification is intended to address an issue where the Generator No 2 control unit does not prevent electrical feedback, which can lead to voltage spikes and potential overheating and damage to electrical components upon engine shutdown. The modifications required by this directive involve the removal of specific diodes (CR201 and CR202) and the installation of a new five-amp circuit breaker (CB235) along with a new suppression filter (A250). The compliance timeline varies depending on the aeroplane’s MSN and the type of generator installed. For aeroplanes with MSN 231 and subsequent that have either the Bosch Generator No 2 with Part Number (P/N) 524.32.12.158 installed or Pilatus PC-12 SB 24-009 incorporated, the modifications must be completed within the next ten flights after the directive's effective date of 25 February 1999 (section 2). For aeroplanes with MSN ranging from 101 to 230 that have the Electro Systems Generator No 2 with P/N 978.87.24.121 and Pilatus PC-12 SB 24-009 incorporated, the modifications must be completed within the next 100 hours of time in service after the directive's effective date. Failure to comply with this Airworthiness Directive could result in significant safety risks, including potential damage to the aeroplane’s electrical system. The regulations do not explicitly state any civil or criminal penalties for non-compliance, but non-compliance could potentially lead to the aircraft being grounded until the modifications are made, which could incur operational and financial losses. Additionally, any resultant damage to the aircraft due to non-compliance may lead to further regulatory scrutiny or legal actions.