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

COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES

Pilatus PC-12 Series Aeroplanes

AD/PC-12/16 Electrical Power - Generator No. 2 Excitation 4/99 TX

Applicability: All Model PC-12 and PC-12/45 with Manufacturers Serial Numbers MSN 101 up to and including MSN 260.

Requirement: 1. Modify the electrical power system in accordance with Pilatus PC-12 Service Bulletin (SB) No 24-012 dated 19 February 1999.

Note: FOCA Switzerland AD HB 99-143 refers.

Compliance: 1. For aeroplanes (MSN 231 and subsequent) with Bosch Generator No 2 Part Number (P/N) 524.32.12.158 installed or Pilatus PC-12 SB 24-010 incorporated - Within the next ten flights after the effective date of this Directive; or

For aeroplanes (MSN 101 up to and including MSN 230) with Electro Systems Generator No 2 P/N 978.87.24.121 and Pilatus PC-12 SB 24-009 incorporated - Within the next 100 hours time in service after the effective date of this directive.

This Airworthiness Directive becomes effective on 25 February 1999.

Background: The Generator No 2 control unit (VR231) does not prevent electrical feedback from the Generator No 2 field excitation on engine shut-down. If the Generator No 2 is not switched off prior to engine shut-down, voltage spikes may be created at relay K234, which could result in overheat damage to electrical components of the generator control unit.

This Directive requires modification of the electrical power system consisting of the removal of diodes (CR201 and 202) and the installation of a new five amp circuit breaker (CB235), together with a new suppression filter (A250). This modification is designed to minimise damage to the electrical system.