Document ID: chunk:federal_register_of_legislation:F2006B09238:reg:734388:p2
Version: federal_register_of_legislation:F2006B09238
Segment Type: reg
Provision Reference: reg 734388 (pt 2/2)
Character Range: 6061–8252

accomplished, within 300 hours time in service after 13 October 1994.

               2.    Within 900 hours time in service after 15 October 1992. Part II:
                   1. Within 300 hours time in service after 19 April 1990 (the compliance date of the previous issue of this Directive), and thereafter at intervals not to exceed 300 hours time in service.

                  2.    Within 600 hours time in service after 19 April 1990 (the compliance date of the previous issue of this Directive), and thereafter at intervals not to exceed 1200 hours time in service.

           Part III:

             Within 2000 hours time in service or 9 months after 15 October 1992, whichever occurs first.

           The compliance of the previous issue of this Directive remains unchanged except for the additional aircraft now included in Requirement Part I.

           This Amendment is effective from 13 October 1994.

           Background: There had been an incident of asymmetric flap where the caution light did not illuminate and the flap indicator remained at zero degrees. Investigation revealed that the primary drive shaft between the two port flaps and the splined coupling between the flap power unit and the starboard primary drive shaft had broken. Further, a secondary drive sensor failed to detect the shaft failure. A further investigation revealed that early serial number splined couplings received inadequate heat treatment. Amendment 1 required replacement of early couplings, a repetitive visual inspection of the flap systems, and an operational check of the torque sensor system.

           Amendment 2 extended the serial number range of torque tubes having had inadequate design and heat treatment, required modification of the wing flap system torque sensor, and required terminating action for the on-going repetitive inspections. Amendment 3 corrected a serial number error in Table 1.

           Amendment 4 is issued in response to a revision of the relevant Transport Canada AD which extends the serial number range of aircraft which require the inspections and possible replacement of splined torque tube couplings in accordance with Requirement Part I.