Commonwealth legislation

AD/AC-SNOW/23 - Vertical Fin Rear Spar

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Commonwealth

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legislative instrument

Plain English Summary

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This AD requires owners/operators of Ayres Thrush (Snow) Commander aircraft listed in SB-AG-38 to perform visual inspections of the vertical fin rear spar at the upper, centre and lower rudder-hinge bearing mounts before 100 hours TIS after 14 Sep 1995 and every 100 hours thereafter, prompted by discovered cracking possibly worsened by bearing corrosion.

Installing Ayres SB-AG-38 (or an Authority-accepted alternative) removes the recurring inspection obligation, shifting costs from repeated inspections to a one‑time modification.

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AD/AC-SNOW/23 - Vertical Fin Rear Spar

COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY

SCHEDULE OF AIRWORTHINESS DIRECTIVES

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Ayres Thrush (Snow) Commander Series Aeroplanes

AD/AC-SNOW/23 Vertical Fin Rear Spar 10/95

Applicability: All aircraft with model and serial number listed in Ayres Corporation Service Bulletin SB-AG-38.

Requirement: Visually inspect the vertical fin rear spar for cracks at the upper, centre and lower rudder hinge bearing mounts.

Compliance: Initially inspect before 100 hours’ time in service after 14 September 1995. Re-inspect at intervals not to exceed 100 hours.

Modification in accordance with Ayres Corporation Service Bulletin SB-AG-38 or a scheme accepted by the Authority cancels the Requirement of this Directive.

Background: When installing the modification of Ayres Corporation Service Bulletin SB-AG-38 on one aircraft the vertical fin rear spar was found to be cracked in several locations.

The cracks may be aggravated by internal corrosion of the bearings restricting free movement.

Source text

Sourced from the Federal Register of Legislation (legislation.gov.au), CC BY 4.0.

1 AD/AC-SNOW/23 - Vertical Fin Rear Spar