63-07-04 ROLLS-ROYCE: Amdt. 549 Part 507 Federal Register April 2, 1963. Applies to All Model Dart Engines.
Compliance required as indicated.
To prevent failures in service of combustion chamber air casings of Pre-Modification 553 standard, which failures have been attributed to fatigue cracks originating around suspension pin soleplates, accomplish the following:
(a) Within the next 100 hours' time in service after the effective date of this AD, on engines with combustion chamber air casings not incorporating Modification 553 standards except engines with air casings of Pre-Modification 97 standards, accomplish (1) or (2):
(1) Install strengthened air casing incorporating Rolls-Royce Modification 553 standards; or
(2) Install air casing straps using:
(i) Mod. 612 standards which modification sets forth a positive location for antitear straps for Pre-Mod 553 air casings; or
(ii) Mod. 1021 standards which modification covers Pre-Mod. 553 air casings which have been modified to Mod. 855 standards providing an additional boss for burner cleaning.
(b) Remove air casings of Pre-Mod. 97 standard at the next engine overhaul and replace with air casings conforming to the standards set forth in (a).
(Rolls-Royce Notice to Operators Dart Engines No. 99 Issue 3 dated June 29, 1962, covers the same subject.)
This directive effective May 2, 1963.