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AD/AB139/8 - Generator Control Unit
Agusta AB139 and AW139 Series HelicopterAgusta AB139 and AW139 Series Helicopters
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Agusta AB139 and AW139 Series Helicopters
| AD/AB139/8 | Generator Control Unit | 5/2009 |
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| Applicability: | All AB139 and AW139 helicopters, all serial numbers (S/N) except for S/N 31002 to S/N 31004 and S/N 31007. |
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| Requirement: | 1. Remove the number 1 and 2 generator control unit (GCU) part number (P/N) 1152550-3 and replace with GCU P/N 1152550-5 or, as an alternative, with two generator control units P/N 1152550-4, in accordance with the instructions of Agusta Bollettino Tecnico 139-133 dated 20 February 2009 or later revision approved by the European Aviation Safety Agency (EASA). |
| The two installed GCUs must have the same P/N at all times (ie two P/N 1152550-4 or two P/N 1152550-5). | |
| 2. GCUs P/N 1152550-3 may not be installed as a replacement spare on any helicopter. | |
| Note: EASA AD 2009-0042 refers. | |
| Compliance: | For Requirement 1 - Within six months after the effective date of this Directive. |
| For Requirement 2 - After the effective date of this Directive. | |
| This Airworthiness Directive becomes effective on 7 May 2009. | |
| Background: | EASA has advised that laboratory tests performed on a new a GCU model under development have shown a potential fault in the overvoltage protection of the currently installed generator control units P/N 1152550-3. This condition, if not corrected, could adversely affect the electrical power generation and distribution system functionalities. |
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James Coyne
Delegate of the Civil Aviation Safety Authority
27 March 2009