AD/HILLER 12/22 Amdt 3 - Main Rotor Hub (Cth)

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

Hiller UH-12 Series Helicopters

AD/HILLER 12/22 Amdt 3

Main Rotor Hub 7/97

Applicability: All models Hiller UH-12 series helicopters with main rotor hubs Part Number 51437, 51437-6, 51437-7, 51437-8, 51437-9, 51437-11, 51437-901 and 51437-11-911 fitted.

Note: Part number 51437-11-911 had been incorrectly listed as 51437-11-011 in the previous amendment.

Requirement: Inspect the inside of the main rotor hub in the area opposite the control rotor trunnion attachments for cracks, using a dye penetrant technique.

Note: FAA AD 73-20-03 refers.

Compliance: Inspect before 50 hours' time in service since last inspected in accordance with a previous amendment of this directive or before 5 hours' time in service after 19 June 1997, whichever occurs later. Thereafter, inspect at intervals not exceeding 50 hours' time in service.

This amendment becomes effective on 19 June 1997.

Background: This amendment removes the need for fluorescent dye penetrant inspection which was introduced by the previous amendment. Further information supplied to the authority has indicated that colour contrast dye penetrant will continue to provide adequate detection of cracks in the main rotor hub.

Amendment 'A' added additional part number hubs to the initial issue of this directive. The description of the required inspection was simplified and a note referring to the FAA AD 73-20-03 was added.

Amendment 2 of this airworthiness directive became effective on 24 April 1997. Apart from requiring use of fluorescent penetrant inspection a part number error in the applicability was corrected.