AD 2005-25-13 Airworthiness Directives; Turbomeca Arriel 2B and 2B1 Turboshaft Engines

This AD applies to Turbomeca Arriel 2B and 2B1 turboshaft engines without modification TU22 incorporated. These engines are installed on, but not limited to, Eurocopter France AS350B3 and EC130B4 helicopters.

You are responsible for having the actions required by this AD performed within the compliance times specified unless the actions have already been done. Visual Checks (f) Within 10 operating hours after the effective date of this AD: (1) Visually check the free turbine shield for cracks using 2.A. through 2.D.(2) of Turbomeca Mandatory Service Bulletin (MSB) A292 72 2821, dated June 27, 2005. (2) Replace the free turbine shield or establish a repetitive check interval using the criteria in the following Table 1: Table 1.—Free Turbine Shield Check, Disposition Criteria Number of cracks: Crack locations using appendix 1 from MSB A292 72 2821: Crack length: Re-check using paragraphs (f)(1) and (f)(2) of this AD, or replace: (i) 0 Not Applicable Not Applicable Re-check shield within 500 N1 cycles. (ii) 1 D-A (A) Less than 170 mm Re-check shield within 100 N1 cycles.     (B) Between 170 mm and 200 mm Re-check shield daily.     (C) Greater than 200 mm Replace shield before further flight. (iii) 1 A-B (A) Less than 201 mm Re-check within 100 cycles.   (5:00 o'clock Area) (B) Between 201 mm and 248 mm Re-check daily.     (C) Greater than 248 mm Replace shield before further flight. (iv) 1 C-D (A) Less than 297 mm Re-check within 100 cycles.   (8:00 o'clock Area) (B) Between 297 mm and 366 mm Re-check daily.     (C) Greater than 366 mm Replace shield before further flight. (v) 2 One in A-B and one in C-D (A) Zone 1 using Appendix 3 of MSB A292 72 2821 Re-check within 100 cycles.     (B) Zone 2 using Appendix 3 of MSB A292 72 2821 Re-check daily.     (C) Zone 3 using Appendix 3 of MSB A292 72 2821 Replace shield before further flight. (vi) 2 Either one or both in D-A Any Replace shield before further flight. (vii) 2 Both in A-B Any Replace shield before further flight. (viii) 2 Both in C-D Any Replace shield before further flight. (ix) 3 or more Any Any Replace shield before further flight. (3) You may treat multiple cracks adjacent to each other as a single crack by using the length measured between the two extremities of the cracks. (4) Single cracks that span two locations must use the location that yields the most conservative re-check interval or replacement requirement. Optional Terminating Action (g) Incorporation of Turbomeca modification TU22 terminates the repetitive visual checks required by this AD. Alternative Methods of

This AD results from reports of several free turbine shields found with large circumferential cracks. We are issuing this AD to prevent failure of the free turbine shield, leading to engine misalignment, in-flight engine shutdown, emergency autorotation landing, or accident.