Document ID: chunk:federal_register_of_legislation:F2005L01043:body:0:p2
Version: federal_register_of_legislation:F2005L01043
Segment Type: other
Provision Reference: 
Character Range: 2786–5326

subject crown tailboom to fin attachment finger doubler.

                  c. thereafter at each 100 hourly `S' inspection.

             Note:  Any CAR 35 repair scheme must include a re-verification of the effectiveness of each of the above inspections in the presence of the repair.
             This Amendment becomes effective on 9 June 2005.
Background:  There has been a history of fatigue cracking at the tailboom to fin attachment area in the reinforcement fairing plate, the crown attachment finger doubler, the tailboom end flange, the tailboom stringers and the inclined fenestron rib P/N/ 360A23.1061.01.  Reports of multiple site cracking in the crown attachment finger doubler of two Australian SA 365C-1's extending, in one case, over a total length of 395mm, indicate that aircraft modified to AMS 365A.07.2457 are still subject to fatigue.  Post modification aircraft are cracking underneath the 1.6mm chemically milled reinforcement fairing plate and are not amenable to visual inspection, due to the location of the internal frame.

             Amendment 1 introduced an X-ray inspection for modified aircraft with the inspection interval aligned to the 25 hour visual inspection interval for unmodified aircraft.

             Amendment 2 extended the X-ray inspection interval to 100 hours and introduced an inspection threshold of 500 hours for repaired aircraft, as a result of laboratory investigation.  There is now also a detailed visual inspection.  Further variations to the threshold and interval will be considered if a fracture mechanics based analysis is received.

             Amendment 3 introduced some operational flexibility by aligning the X-ray and visual inspections with the 100 hour `S' inspection.  The visual inspection is now a separate requirement and applies to all models.

             Amendment 4 enhanced the visual inspection of Service Bulletin No. 05.04 by requiring the external paint to be removed.  This followed the discovery of a 45mm crack in a 'fairing' plate - inspection of this part was hindered by a thick flexible paint coating.  To alleviate the burden of repetitive paint stripping, an option of coating with a suitable clear lacquer was introduced.

             Amendment 5 is issued to clarify applicability by specifying affected helicopters; with no change to technical content.

   The original issue of this Airworthiness Directive became effective on 28 February 1981.

David Villiers
Delegate of the Civil Aviation Safety Authority

19 April 2005