AD 71-06-05

71-06-05 ROLLS-ROYCE: Amdt. 39-1172. Applies to Rolls-Royce Dart engine models 506, 510, 511, 511-7E, 514, and 514-7 installed on, but not necessarily limited to British Aircraft Corporation Viscount 744 and 745D; Fairchild F-27 and F-27B; and Fokker F-27 airplanes.

Compliance is required as indicated, unless already accomplished.

(a) For all engines installed on airplanes having an average daily utilization rate of more than three hours flight time per day, comply with paragraph (c) within the next 4,000 hours' time in service after the effective date of this AD, or at the next engine overhaul, whichever occurs first.

(b) For all engines installed on airplanes having an average daily utilization rate of three hours flight time or less per day, comply with paragraph (c) within the next 2,000 hours' time in service after the effective date of this AD, or at the next engine overhaul, whichever occurs first.

(c) Replace Rolls-Royce turbine disc retaining bolt P/N RK 33044 with P/N RK 43376 in accordance with Rolls-Royce Dart Aero Engine Service Bulletin Number Da 72-347, Revision 2, dated July 24, 1970, or later ARB-approved revision, or an FAA-approved equivalent.

(d) For the purpose of complying with this AD, the average daily utilization rate shall be determined on the basis of the average daily utilization rate for the 12-month period immediately preceding the effective date of this AD.

This amendment becomes effective April 12, 1971.