1AD/AL 250/61 Amdt 3 - Gas Producer Turbine Assembly and Second Stage Nozzle Seal

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 250/61

Amdt 3

Gas Producer Turbine Assembly and Second Stage Nozzle Seal

8/88

Applicability: All 250-C30/C30S engines installed in or intended for installation in Sikorsky S-76 aircraft and/or all C30 series engines with serial numbers listed in the Requirement Document.

Requirement: 1. Inspect second stage turbine 29-34 labyrinth seal for rub in accordance with Allison CEB-A-72-3127R.3.

FAA AD 84-17-51 R1 Amendment 39-4963 refers to the original and Revision 1 of the Requirement Document.

2. Increase second stage nozzle 29-34 labyrinth seal clearance in accordance with Allison CEB-A-72-3131, Rev.1.

Compliance: Part 1 above: Applicable engines having 100 hours or less time in service since gas producer turbine rotor assembly overhaul, repair or disassembly. Inspect the second stage turbine nozzle interstage seal for evidence of rub within the next 50 hours’ time in service after 5 September 1984.

Part 2 above:

(i) For engines assembled in accordance with CEB-A-72-3127 Revision 1 concurrent with inspection detailed in Part 1 above.

(ii) For engines assembled in accordance with CEB-A-72-3127 or Allison Message THO-1977W-RMG-84 unless already accomplished no later than the next overhaul certified after 28 February 1985.

Compliance with a previous issue of this Directive constitutes compliance with this amendment.

Background: Amendment 3 to this Directive reflects the latest revision to CEB-A-72-3127.