AD/Al 250/86 Amdt 2 Compressor Adaptor Coupling (Cth)
AIRWORTHINESS DIRECTIVE
On the effective date specified below, and for the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/AL 250/86 Amdt 1 and issues the following AD under subregulation 39.001(1) of CASR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.
Allison Turbine Engines - 250 Series
| AD/AL 250/86 Amdt 2 | Compressor Adaptor Coupling | 6/2005 |
Applicability: | Rolls-Royce Corporation (formerly Allison Engine Company, Allison Gas Turbine Division, and Detroit Diesel Allison) 250-B17, -B17B, -B17C, -B17D, -B17E, 250-C20, -C20B, -C20F, -C20J, -C20S, and -C20W series turboprop and turboshaft engines with the compressor adaptor couplings installed listed in Table 1 of this Directive. Table 1. - Affected Compressor Adaptor Couplings
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| These engines are installed on, but not limited to, the aircraft in Table 2 of this Directive: Table 2. - Applicable Aircraft
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Requirement: | 1. Alcor Compressor Adaptor Couplings Remove Alcor compressor adaptor couplings, P/Ns 23039791AL, 23039791AL-1, -2, and -3 from service. 2. EXTEX and SAP Compressor Adaptor Couplings Remove EXTEX and SAP compressor adaptor couplings, P/Ns A23039791, E23039791, E23039791-1, -2, and -3, EH23039791, and EH23039791-1, -2, and -3, from service. |
| 3. RRC Compressor Adaptor Couplings Remove RRC compressor adaptor couplings, P/Ns 23039791-1, -2, and -3 from service 4. Installation Requirements for Compressor Adaptor Couplings Machine the compressor impeller as follows: (a) Select and measure the pilot outside diameter (OD) of a new larger dash size coupling. (b) For example, if a -1 coupling was removed, a -2 coupling must be installed. (c) If a -3 coupling is removed, a new impeller is required. (d) Machine the inside diameter (ID) of the compressor impeller to achieve a fit of 0.0000 to -0.0013 inch. No fretting is allowed on the impeller after machining. (e) Due to previous fretting, an impeller with a -1 coupling removed might have to be machined for a -3 coupling. Plating of the impeller ID is not allowed. (f) Fluorescent penetrant inspect the impeller. (g) Install a new compressor adaptor coupling, P/N 23076559-2 or -3; or (h) If a new impeller is installed, then install compressor adaptor coupling, P/N 23076559-1. (i) Heating of the impeller per the engine overhaul manual is required to install the coupling to achieve the target fit specified in Table 3 of this Directive:
(j) The mating surfaces of the impeller and coupling must not have any fretting. Do not install a -1 coupling into a used impeller. Note: FAA AD 2004-26-09 Amdt 39-13921 refers. |
Compliance: | 1. Alcor Compressor Adaptor Couplings (a) For couplings with 600 or more operating hours-since-new as of the effective date of this Directive, or the operating hours are unknown and cannot be determined, remove couplings from service within 50 additional operating hours after the effective date of this Directive or by 15 June 2005, whichever occurs later. (b) For couplings with fewer than 600 operating hours-since-new on the effective date of this Directive, remove couplings from service before exceeding 650 operating hours-since-new or by 15 June 2005, whichever occurs later. 2. EXTEX and SAP Compressor Adaptor Couplings (a) For couplings with 600 or more operating hours-since-new as of the effective date of this Directive, or the operating hours are unknown and cannot be determined, remove couplings from service within 100 additional operating hours after the effective date of this Directive or by 15 June 2005, whichever occurs later. (b) For couplings with fewer than 600 operating hours-since-new on the effective date of this Directive, remove couplings from service within 150 additional operating hours after the effective date of this Directive or by 15 June 2005, whichever occurs later. 3. RRC Compressor Adaptor Couplings At the next time the compressor rotor is disassembled for any reason, but not later than 1 March 1 2012. 4. Installation Requirements for Compressor Adaptor Couplings From the effective date of this Directive. Definition For the purposes of this Directive, next access is defined as when the compressor module is separated from the engine and disassembled for any reason. |
| This Amendment becomes effective on 9 June 2005. |
Background: | This AD results from nine reports of engine shutdown caused by compressor adaptor coupling failure. Amendment 1 amended the compliance period. Amendment 2 corrects a typographical error in Table 2 of the Applicability and removes the discrepancy in the compliance times for EXTEX and SAP couplings. Amendment 1 of this Directive became effective on 22 March 2005. The original issue of this Directive became effective on 17 March 2005. |
James Coyne
Delegate of the Civil Aviation Safety Authority
27 April 2005
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