Commonwealth legislation

AD/AL 250/38 - Idler Gearshafts - Replacement

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legislative instrument

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This airworthiness directive requires operators of Allison 250-C28 and 250-C30 engines fitted with specific idler gearshafts (P/Ns 6898980, 6898591, 6898652) to replace those parts by set cycle limits to prevent accessory-drive gearbox gearshaft failure. Operators must schedule replacements by 9,000 cycles for 250-C28, 2,000 cycles for 250-C30, or within 50 cycles if already over the limit, imposing defined maintenance, cost and scheduling obligations.

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AD/AL 250/38 - Idler Gearshafts - Replacement

COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY

SCHEDULE OF AIRWORTHINESS DIRECTIVES

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Allison Turbine Engines - 250 Series

AD/AL 250/38 Idler Gearshafts - Replacement 10/79

Applicability: All 250-C28 and -C30 series models fitted with generator idler gearshaft P/N 6898980 or 6898591 and 77 tooth idler gearshaft P/N 6898652.

Document:	1.	Allison 250-C28 CEB No. 72-2003; or Allison 250-C30 CEB No. 72-3003; or
	2.	FAA AD 79-16-06 Amendment 39-3527 also refers.
Compliance:	1.	For 250-C28 engines: Prior to reaching 9000 cycles.
	2.	For 250-C30 engines: Prior to reaching 2000 cycles.
	3.	For engines which may have exceeded the maximum permissible number of cycle at the time of promulgation of this Directive 3 September 1979, within 50 cycles.

Background: This Directive is issued to prevent sudden power loss due to accessory drive gearbox gearshaft failure.

Source text

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

1 AD/AL 250/38 - Idler Gearshafts - Replacement

COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY

SCHEDULE OF AIRWORTHINESS DIRECTIVES

Allison Turbine Engines - 250 Series

AD/AL 250/38 Idler Gearshafts - Replacement 10/79

Applicability: All 250-C28 and -C30 series models fitted with generator idler gearshaft P/N 6898980 or 6898591 and 77 tooth idler gearshaft P/N 6898652.

Document:	1.	Allison 250-C28 CEB No. 72-2003; or Allison 250-C30 CEB No. 72-3003; or
	2.	FAA AD 79-16-06 Amendment 39-3527 also refers.
Compliance:	1.	For 250-C28 engines: Prior to reaching 9000 cycles.
	2.	For 250-C30 engines: Prior to reaching 2000 cycles.
	3.	For engines which may have exceeded the maximum permissible number of cycle at the time of promulgation of this Directive 3 September 1979, within 50 cycles.

Background: This Directive is issued to prevent sudden power loss due to accessory drive gearbox gearshaft failure.