Airworthiness Directive · Amendment 39-17082 · Rolls-Royce plc Turbofan Engines
Rolls-Royce plc Turbofan Engines
This AD applies to Rolls-Royce plc (RR) models RB211-Trent 970-84, 970B-84, 972-84, 972B-84, 977-84, 977B-84, and 980-84 turbofan engines.
We are superseding an existing airworthiness directive (AD) for all Rolls-Royce plc (RR) models RB211-Trent 970-84, 970B-84, 972- 84, 972B-84, 977-84, 977B-84, and 980-84 turbofan engines. That AD currently requires inspecting the intermediate-pressure (IP) shaft rigid coupling splines for wear resulting in rearward movement of the IP turbine. This AD requires the same inspections, and new inspections based on possible changes in wear rate. This AD was prompted by RR identifying wear beyond engine manual limits on the abutment faces of the splines. RR also determined that an additional IP shaft rigid coupling configuration requires inspection. We are issuing this AD to detect wear on the abutment faces of the splines, which could result in loss of disc integrity, an uncontained failure of the engine, and damage to the airplane.
(i) Initially borescope-inspect the IP shaft rigid coupling splines. Use paragraphs 3.A.(2)(a) through 3.A.(2)(k) of RR RB211 Trent 900 Series Propulsion Systems Alert Non-Modification Service Bulletin (NMSB) No. RB.211-72-AG329, Revision 4, dated March 23, 2012, to do the inspection. Inspect per the following:
(A) If the IP shaft rigid coupling has 250 or fewer flight cycles-since-new (FCSN) on the effective date of this AD, inspect before accumulating 400 FCSN; or
(B) If the IP shaft rigid coupling has more than 250 FCSN on the effective date of this AD, inspect within 150 additional flight cycles.
(ii) Repetitively borescope-inspect the IP shaft rigid coupling splines. Use paragraphs 3.A.(2)(a) through 3.A.(2)(l) of RR RB211 Trent 900 Series Propulsion Systems Alert NMSB No. RB.211-72-AG329, Revision 4, dated March 23, 2012, to determine the re-inspection interval and to do the inspections.
(iii) If during the initial or any repetitive inspection, the average spline crest length measured dimension is less than 0.5 millimeters (mm), remove the engine from service before further flight.
(i) At every shop visit after the effective date of this AD, where the IP shaft rigid coupling is exposed, visually inspect and magnetic particle inspect (MPI) the IP shaft rigid coupling splines.
(ii) At every shop visit after the effective date of this AD, where the IP shaft rigid coupling is not exposed:
(A) Inspect the IP shaft as specified in paragraph (f)(1) of this AD and determine the next inspection interval using Figure 10 of RR RB211 Trent 900 Series Propulsion Systems Alert NMSB No. RB.211-72-AG329, Revision 4, dated March 23, 2012; and
(B) Reject any IP shaft with an average spline crest length measured dimension less than 1.0 mm.
After any shop inspection, where the IP shaft rigid coupling is exposed, perform a borescope inspection per paragraph (f)(1) of this AD within 400 cycles after the in-shop visual inspection and MPI.
(i) Before installing an engine in a new position on the same airplane, or before installing an engine on a different airplane in any position:
(A) Inspect the IP shaft rigid coupling splines as specified in paragraphs (f)(1) or (f)(2) of this AD as applicable and determine the next inspection interval using Figure 10 of RR RB211 Trent 900 Series Propulsion Systems Alert NMSB No. RB.211-72-AG329, Revision 4, dated March 23, 2012; and
(B) Do not install an engine that has an IP shaft with an average spline crest length measured dimension of less than 0.5 mm.
(ii) Before installing an engine in the same position on the airplane it was removed from:
(A) Inspect the IP shaft rigid coupling splines using paragraph (f)(1) or (f)(2) of this AD as applicable and determine the next inspection interval; and
(B) Do not install an engine that has an IP shaft with an average spline crest length measured dimension of less than 0.5 mm.
(i) Initially borescope-inspect the IP shaft rigid coupling splines before accumulating 400 FCSN or 400 cycles since the last inspection per paragraph (g)(2)(i) of this AD. Use paragraph 3.A.(2) of RR RB211 Trent 900 Series Propulsion Systems Alert NMSB No. RB.211-72-AG871, dated March 23, 2012, to do the inspection.
(ii) Repetitively borescope-inspect the IP shaft rigid coupling splines. Use paragraphs 3.A.(2)(e), 3.A.(2)(f), and 3.A.(3) of RR RB211 Trent 900 Series Propulsion Systems Alert NMSB No. RB.211-72-AG871, dated March 23, 2012, to determine the re-inspection interval and to do the inspections.
(i) At every shop visit after the effective date of this AD, where the IP shaft rigid coupling is exposed, visually inspect and MPI the IP shaft rigid coupling splines.
(ii) At every shop visit after the effective date of this AD, where the IP shaft rigid coupling is not exposed, borescope-inspect using paragraphs 3.A.(2)(a) through 3.A.(2)(f) of RR RB211 Trent 900 Series Propulsion Systems Alert NMSB No. RB.211-72-AG871, dated March 23, 2012.
(A) If at the time of initial inspection, the average value of length “B” is equal to, or less than, 6.00 mm, repeat the borescope inspection using paragraph (g)(1) or (g)(2) of this AD within 400 flight cycles.
(B) If at the time of initial inspection the average value of length “B” is greater than 6.00 mm, MPI the IP turbine shaft, and visually inspect and MPI the intermediate turbine shaft and IP rigid coupling.
After any shop inspection, where the rigid shaft coupling is exposed, perform a borescope inspection per paragraph (g)(1) of this AD within 400 cycles after the in-shop visual inspection and MPI.
For the purpose of this AD, a shop visit is the induction of an engine into the shop for maintenance involving the separation of pairs of major mating engine flanges, except that the separation of engine flanges solely for the purposes of transportation without subsequent engine maintenance does not constitute an engine shop visit.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
Engines
