AD 80-23-01 ACTIVE

80-23-01 ROLLS-ROYCE, LTD.: Amendment 39-3966. Applies to Rolls-Royce, Ltd., DART 506, 510, 511, 514, 515, 520, 525, 526, 527, 528, 529, 530, 531, 532, 533, 534, 535, 536, 542, 543, 550, and all variants turboprop engines.

Compliance required as indicated, unless already accomplished.

To preclude possible frettage fatigue failure of low pressure impellers, inspect for cracks and modify or remove from service all low pressure impellers installed in the following DART model engines:

1. DART 506, 510, 511, 514, 515, and their variants; and DART 520, 525, 526, 527, 528, 529, 530, 531, 532, 533, 534, 535, 536, 550, and all variants of these marks equipped with a low pressure impeller which has run previously in a DART 506, 510, 511, 514, 515, or any variant of these engines.

a. After November 30, 1980, no low pressure impeller may exceed 5,000 flight cycles since new without inspection for cracks and incorporation of Modification 1732, in accordance with Rolls-Royce DART Alert Service Bulletin No. Da72-A445, Revision 4, dated October 27, 1980. Remove from service low pressure impellers having crack indications.

b. After November 30, 1980, prior to further flight, all low pressure impellers for which the flight cycles since new cannot be positively established, must be inspected and modified to incorporate Modification 1732; in accordance with Rolls-Royce DART Alert Service Bulletin No. Da72-A445, Revision 4, dated October 27, 1980. Remove from service, low pressure impellers having crack indications.

c. Remove from service not later than May 31, 1981, all low pressure impellers which have not been inspected for cracks and do not have modification 1732 incorporated.

2. DART 520, 525, 526, 527, 528, 529, 530, 531, 532, 533, 534, 535, 536, 550, and their variants equipped with a low pressure impeller which has not run previously in a DART 506, 510, 511, 514, 515 or any variant of these engines.

a. After December 31, 1982, no low pressure impeller may exceed 9,000 flight cycles since new without inspection for cracks and incorporation of Modification 1732, in accordance with Rolls-Royce DART Alert Service Bulletin No. Da72-A445, Revision 4, dated October 27, 1980. Remove from service low pressure impellers having crack indications.

b. After December 31, 1982, prior to further flight, all low pressure impellers for which the flight cycles since new cannot be positively established, must be inspected and modified to incorporate Modification 1732, in accordance with Rolls-Royce DART Alert Service Bulletin No. Da72-A445, Revision 4, dated October 27, 1980. Remove from service low pressure impellers having crack indications.

c. Remove from service not later than December 31, 1984, all low pressure impellers which have not been inspected for cracks and do not have Modification 1732 incorporated.

3. DART 542 and 543 model engines and their variants.

a. After December 31, 1981, no low pressure impeller may exceed 9,000 flight cycles since new without inspection for cracks and incorporation of Modification 1732, in accordance with Rolls-Royce DART Alert Service Bulletin No. Da72-A445, Revision 4, dated October 27, 1980. Remove from service low pressure impellers having crack indications.

b. After December 31, 1981, prior to further flight, all low pressure impellers for which the flight cycles since new cannot be positively established, must be inspected and modified to incorporate Modification 1732, in accordance with Rolls-Royce DART Alert Service Bulletin No. Da72-A445, Revision 4, dated October 27, 1980. Remove from service low pressure impellers having crack indications.

c. Remove from service not later than December 31, 1983, all low pressure impellers which have not been inspected for cracks and do not have modification 1732 incorporated.

NOTE: For the purposes of this AD, a flight cycle is considered to be an engine operating sequence fromtakeoff to landing.

Airplanes may be ferried in accordance with the provisions of FAR 21.197 to a base where the AD can be accomplished.

Upon request of the operator, equivalent means of compliance with the requirements of this AD may be approved by the Chief, Engineering and Manufacturing Branch, FAA, New England.

The Manufacturer's Alert Service Bulletin identified and described in this directive is incorporated herein and made a part hereof pursuant to 5 U.S.C. 552(a)(1). All persons affected by this directive who have not already received this document from the manufacturer may obtain copies upon request to Technical Publications Department, Rolls-Royce, Ltd., East Kilbride G74 4PY, Scotland. The document may also be examined at Federal Aviation Administration, New England Region, 12 New England Executive Park, Burlington, Massachusetts, 01803, and at FAA Headquarters, 800 Independence Avenue, S.W., Washington, D.C. A historical file on this AD which includes the incorporated material in full is maintained by the FAA at its Headquarters in Washington, D.C., and at the New England Region Office. Upon request of the operator, an FAA Maintenance Inspector, subject to prior approval of the Chief, Engineering and Manufacturing Branch, FAA, New England Region, may adjust the compliance date(s) specified in this AD to permit compliance at an established inspection period of the operator if the request contains substantiating data to justify the increase for that operator.

This amendment becomes effective October 30, 1980.