72-18-02 R1 ROLLS-ROYCE LTD: Amendment 39-1506 as amended by Amendment 39-4638. Applies to Rolls-Royce DART Mk.506, 510, 511, 514, 515, 525 through 532 and variants series turboprop engines not incorporating Rolls-Royce DART Modification 1625 or 1626 fuel burners.
Compliance is required as indicated, unless already accomplished.
1. Compliance for all affected DART engines except the Mk.530 is based on an effective date of August 24, 1972.
2. Compliance for the DART Mk.530 engine is based on an effective date of May 12, 1983.
To prevent stress, corrosion, cracking, and failure of fuel burner shroud nuts accomplish the following:
(a) At the next disassembly of an engine for cause, after the effective date of this AD, unless already accomplished, comply with paragraph (c).
(b) For engines that have been out of service for more than 6 months, that are not stored in a moisture vapor-proof bag for which the humidity indicator shows "SAFE," before returning such an engine to service after the effective date of this AD, unless already accomplished, comply with paragraph (c).
(c) Inspect the fuel burner shroud nuts, P/N RK14285, on each fuel burner shroud assembly, P/N RK14283A, in accordance with the following, as applicable:
(1) Visually inspect the fuel burner shroud nuts, P/N RK14285, for failure and cracks. If any fuel burner shroud nuts are found failed or cracked, before further flight
(i) replace each affected fuel burner shroud assembly, P/N RK14283A, with a serviceable assembly of the same part number or with an equivalent fuel burner shroud assembly that is approved for use in the engine; and
(ii) Visually inspect the turbine, combustion chamber, discharge nozzle, and H.P. nozzle guide vanes for evidence of overheating and foreign object damage. If overheating or damage is found that exceeds the limitations in the approved Rolls-Royce maintenance manual for the engine, before further flight repairthe engine in accordance with that manual.
(2) Visually inspect the fuel burner shroud nuts, P/N RK14285, for the symbol "H" engraved on a serration that is adjacent to a serration on which the symbol "C" is engraved. If any fuel burner shroud nuts, P/N RK14285, are found that are not so engraved, before further flight comply with subparagraph (c)(3) for those nuts.
(3) Inspect one serration of each subject fuel burner shroud nut, P/N RK14285, for hardness and comply with one of the following:
(i) If any fuel burner shroud nuts, P/N RK14285, are found that have hardness of 321 Brinnel (10mm-3000KG) or more, before further flight replace each affected fuel burner shroud assembly, P/N RK14283A, with a serviceable assembly of the same part number or with an equivalent fuel burner shroud assembly that is approved for use in the engine.
(ii) For fuel burner shroud nuts, P/N RK14285, that are found to have hardness of less than 321 Brinnel (10mm-3000KG), before further flight vibro engrave the symbol "H" on the serration that was inspected in accordance with this paragraph, unless already accomplished, and vibro engrave the symbol "C" on an adjacent serration. Fuel burner shroud assemblies, P/N RK14283A, containing fuel burner shroud nuts, P/N RK14285 so engraved, may be returned to service.
(Rolls-Royce DART Service Bulletin No. Da 73-68, dated October 1, 1971, covers this same subject.)
Amendment 39-1506 became effective August 24, 1972
This Amendment 39-4638 becomes effective May 12, 1983.