72-23-02 ROLLS ROYCE (1971) LTD: Amendment 39-1547. Applies to Rolls Royce Dart Models 542-4, -4K, -10, -10J, and -10K engines. These engines are installed on, but not necessarily limited to, Convair 340/440 airplanes that have had subject engines installed by modification, and NAMC YS-11 and YS-11A airplanes, all series. (NOTE: Subject Convair 340/440 airplanes are also known as Convair 600 and 640 airplanes.)
Compliance is required as indicated.
To prevent damage to the rear face of the first stage impeller that could lead to impeller disintegration in service, accomplish the following:
(a) Within the next 300 flights after the effective date of this AD, or before the accumulation of 2,000 flights on the compressor since installed new or since last compressor overhaul, as applicable, whichever occurs later, unless already accomplished, modify the oil drain plug, P/N RK.35189, and refit it to the engine in accordance with Rolls Royce Dart Aero Engine Service Bulletin Number DA 72-383, Revision 1, dated November 30, 1971, or an FAA-approved equivalent. Identify the modified drain plug as P/N RK. 46404.
(b) Within the next 300 flights after incorporation of the modification specified by paragraph (a), and thereafter at intervals not to exceed 300 flights from the last inspection visually inspect the surfaces of the drain plug, P/N RK.46404, for the presence of aluminum particles. If aluminum particles are found during an inspection required by this paragraph, before further flight comply with paragraph (e).
NOTE: During inspections required by paragraph (b) particular attention should be directed to the sealing ring recess.
(c) For an engine that is subject to an FAA-approved continuous airworthiness maintenance program that includes periodic inspection for freedom of engine rotation and periodic inspection of the oil filter, comply with the following:
(1) At each inspection for freedom of engine rotation, listen for unusualnoises from the compressor area; and
(2) At each inspection of the oil filter, visually inspect the filter for traces of fine aluminum dust in the bottom of the filter cap or in suspension in the residual oil in the filter cap.
(3) If any unusual noise emanates from the compressor area during an inspection required by subparagraph (c) (1) or if any trace of fine aluminum dust is found during an inspection required by subparagraph (c) (2), before further flight comply with paragraph (e).
Change to an approved program that affect either the interval or performance of inspections required by this AD must be approved by the assigned FAA Maintenance Inspector.
(d) For engines that are not subject to an FAA-approved continuous airworthiness maintenance program that includes periodic inspection for freedom of engine rotation and periodic inspection of the oil filter comply with the following:
(1) At each inspection required by paragraph (b) -
(i) Inspect thefirst stage impeller for freedom of rotation by rotating it at least one full turn in each direction, and listen for unusual noises from the compressor area.
(ii) Visually inspect the oil filter for traces of fine aluminum dust in the bottom of the filter cap or in suspension in the residual oil in the filter cap.
(2) If the first stage impeller does not rotate freely in each direction or if any unusual noise emanates from the compressor area during an inspection required by subparagraph (d)(1)(i), or if any trace of fine aluminum dust is found during an inspection required by subparagraph (d)(1)(ii), before further flight comply with paragraph (e).
(e) Remove one combustion chamber and visually inspect the compressor outlet elbow, flame tube, discharge nozzle, H.P. nozzle guide vanes, and H.P. turbine blades for evidence of metal spatter and surface roughness or impact damage due to the passage of a foreign object. If any of these indications are found, before further flight rebuild the engine in accordance with Rolls Royce Dart Aero Engine Service Bulletin Da 72-383, Revision 1, dated November 30, 1971, or an FAA-approved equivalent.
(f) For the purpose of complying with this AD, a flight is an operating sequence consisting of an engine start, takeoff operation, landing, and engine shutdown. The number of flights may be determined by actual count or, subject to acceptance by the assigned FAA Maintenance Inspector, may be calculated by dividing the compressor section's time in service by the operator's fleet average time for airplanes equipped with the subject type engines.
(g) At the request of the operator, an FAA Maintenance Inspector, subject to prior approval of the Chief, Aircraft Certification Staff, FAA Europe, Africa, and Middle East Region, may adjust the repetitive inspection intervals 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.
(h) The repetitive inspections required by this AD may be discontinued on engines that have been rebuilt in accordance with paragraph (e).
This amendment supersedes Amendment 39-1381 (37 F.R. 666), AD 72-02-04.
This amendment becomes effective October 26, 1972.