AIRWORTHINESS DIRECTIVE For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.001(1) of CASR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section. BAe Systems (Operations) Jetstream 4100 Series Aeroplanes AD/J4100/6 Wing Upper Splice Plate 4/2008 DM Applicability: All Model Jetstream Series 4100 aircraft, construction numbers 41004 through 41096, and 41102 through 41004, on which either: Service Bulletin (SB) J41-57-019 or equivalent inspection has not been carried out; or, SB J41-57-019 or equivalent inspection has been carried out and the wing upper splice plates have an eddy current reading of less than 35.0% IACS. Note: Aircraft construction numbers 41097 through 41001 were inspected during production and do not require additional action. Requirement: 1. Accomplish an eddy current inspection of the wing upper splice plate part number 14157126-3 in accordance with the instructions of British Aerospace Regional Aircraft SB J41-57-019 original issue, or Revision 1, or later EASA approved revision; or using an equivalent approved procedure. Note 1: Wing upper splice plates that have an eddy current reading at or above 35.0% IACS require no further action. 2. On aircraft that have an eddy current reading of less than 35.0% IACS, accomplish the borescope inspection of the wing upper splice plate part number 14157126-3 in accordance with paragraphs 2.A. and 2.B. of BAE Systems (Operations) Limited SB J41-57-020 Revision 1, or later EASA approved revision. 3. When no corrosion is found, re-inspect the wing upper splice plate part number 14157126-3 in accordance with paragraph 2.B. of BAE Systems (Operations) Limited SB J41-57-020 Revision 1, or later EASA approved revision. 4. When corrosion is found that is less than the limits specified in Figure 1 of SB J41-57-020 Revision 1, or later EASA approved revision, re-inspect the wing upper splice plate part number 14157126-3 in accordance with paragraph 2.B. of BAE Systems (Operations) Limited SB J41-57-020 Revision 1, or later EASA approved revision. 5. When corrosion is found that is outside the acceptable limits, either replace the wing upper splice plate in accordance with SB J41-57-021 Revision 1, or later EASA approved revision, or repair the wing upper splice plate in accordance with a repair approved by EASA. Note 2: Installing a replacement wing upper splice plate part number 14157126-3PF in accordance with SB J41-57-021 Revision 1, or later EASA approved revision, provides terminating action for the repeat inspections of Requirements 3 or 4, as applicable. Note 3: EASA AD 2007-0056 refers. Compliance: 1. Within 3 months after 20 February 2008, unless already accomplished. 2. Before further flight after the Requirement 1 inspection. 3. At intervals not to exceed 12 months. 4. At intervals not to exceed 12 months and, within 3 years of the corrosion being discovered, replace the wing upper splice plate in accordance with SB J41-57-021 Revision 1, or later EASA approved revision. 5. Before further flight. This Airworthiness Directive becomes effective on 20 February 2008. Background: A report was received of corrosion of the wing upper splice plate detected during a routine four year structural inspection of an in-service aircraft. Investigation revealed that the susceptibility of the wing upper splice plate to corrosion was linked to the material conductivity. Revision 1 of SB J41-57-020 extends applicability to include aircraft construction numbers 41102 through 41104. David Villiers Delegate of the Civil Aviation Safety Authority 15 February 2008