**Federal Aviation Administration**

Summary of Meeting with Rolls
- Royce plc for Regulatory Docket No. FAA
- 2013
- 1049 Date of Meeting: March 13, 2014 Attendees : Federal Aviation Administration Vincent Bennett, Esq., ANE
- 7, (781) 238
- 7044 Thomas Boudreau, ANE
- 140, (781) 238
- 7140 Anthony Cerra, ANE
- 142, (781) 238
- 7128 Diane Cook, ANE
- 111, (781) 238
- 7111 Tara Fitzgerald, ANE
- 111, (781) 238
- 7130 Robert Ganley , ANE
- 110, (781) 238
- 7110 Karen M. Grant, ANE
- 142, (781) 238
- 7142 Robert Green, ANE
- 142, (781) 238
- 7754 Alan Strom, ANE
- 111, (781) 238
- 7143 Thomas Thorson, ANM
- 140S, (425) 917
- 6508 Rolls
- Royce plc Dave Brown , ( 44 ) 1332 24 6640 Richard Corran, (44) 7794 21 4351 Neil Davies, (44) 1332 82 3304 Colin French, ( 44 ) 1332 70 8343 Gareth Jones, (44) 7794 21 4217 I ain Park, ( 44 ) 1332 24 9292 Paul Stow , ( 44 ) 1332 82 3516 Belinda Swain, (44) 7837 37 6396
**I. Purpose of meeting**  Purpose of the meeting is for Rolls
- Royce to present to the FAA whatever information Rolls
- Royce deems necessary to fully respond to FAA questions
. **II. Outcomes** 
 Rolls
- Royce to have communicated all the information needed to clarify their answers to FAA questions
.  Rolls
- Royce will have submitted all the information for FAA to determine the outcome of the petition for exemption
.**III. Rolls**  **- Royce addre**  **ssed the following FAA clarifying questions :** 

1. Please clarify

your response for why

the exemption is needed b y providing data to show why

the Trent 1000 Package C configuration does not meet 33.27 requirements while previous Trent 1000 models met the requirement. o **Rolls -**  **Royce provided an overview of the exemption request .**  o **Rolls -**  **Royce provided description of historical experience of the HP shaft system within the three shaft engine design.**  2. Please clarify

what testing Rolls
- Royce has done on Trent 1000 Package C configuration engines to support your terminal speed estimates. o **Rolls -**  **Royce provided a description of the derivation of HPT terminal speed and determination of HPT disc capability**  **.**  **Engine conditions at all potential terminal speed conditions identified**  **.**  **Thermodynamic assessment of the turbine behaviour post shaft failure**  **.**  **Worst -**  **case turbine inertia used in the assessment .**   **Performance data validated by real engine experience .**   **Frictional effects are based on real engine experience .**   **Capacity and efficiency understanding validated by engine and**  **rig test .**   **Control system behaviour understood .**   **Terminal speed calculation methodology is validated .**   **HPT disc capability proven by test at temperature .**  3. Please clarify

your response to which models require the exemption by providing the terminal speeds and margins for each model. o **Rolls -**  **Royce provided engine overspeed margin comparison for each model**  **.** 4. In the Compensating factors for exemption from Section 33.27(f)(6) report, DNS192492 iss1, Rolls
- Royce notes that no failure of the HP shaft sy stem torque path on the Trent family

of Rolls
- Royce large, civil , 3
- shaft turbofan engines in more than 228 million flight hours service experience supports a probability of failure rate of 3.1x10
- 9 failure per flight hour. The cited experience dates back to 1972, encompasses all 3
- shaft service experience, but only through October 2012. What is the sum of the service experience and associated failure rate through the end of December 2013? o **Rolls -**  **Royce provided detailed summa ry of fleet hours and flight**  **cycles for RB211 -**  **22B, RB211**  **- 524B, B3 and B4, RB211**  **- 524B2 and C2,**  **RB211 -**  **524D4, RB211 -**  **524H and H -**  **T, RB211 -**  **524G, H, G -**  **T and H -**  **T, RB211**  **- 535C, RB211**  **- 535E4 and E4**  **- B, Trent 700, Trent 800, Trent**  **500, Trent 900, and Trent 1000 engines through December 2013.** 5. Please clarify how the cited service experience (i.e., 244 million hours without a failure) is relevant to the Package C1 and associated derivative engine models by providing: a. A summary

of the HPT maximum permissible (redline) speeds , disk burst speeds, and predicted HPT rotor terminal speeds for a shaft s ys tem separation, with a description of the prediction method used for the terminal speed calculation for the RB211 and Trent family of engines; and b. Detailed descriptions of any rig, engine tests, or other experience used for validation of the anal ytical model used to predict terminal rotor speeds due to the HPT rotor loss of load for the Package C1 engines. Ref Question a., 'the 2nd question' as answered b y Iain Park 3/6/14 at 12:59 PM
. Please provide the burst speeds and predicted terminal speeds for the HPT of the historical service engines. o **Rolls -**  **Royce provided an engine overspeed margin comparison for the Trent 1000, Trent 500, Trent 800, Trent 900, RB211**  **- 524, and**  **RB211 -**  **535 engine s for terminal speed and redline conditions.**  o **Rolls -**  **Royce provided detailed descriptions of the engine testing used to derive HPT terminal speed.**   **The modelling method has been validated against IP turbine shaft failure events.**  **HP shaft failure has not been directly validated as RR has never had an HP Shaft failure.**  6. Rolls
- Royce stated that the cited service experience supports a probability of failure rate of 2.87x10
- 9 failures per flight hour. Please clarify the HPT shaft experience on RB211 and Trent engines that apply to the Trent 1000 Package C1 engines by

providing s tress levels, normalized bulk stress and peak feature
specific stress values, and calculated lives for both the Package C1 HPT shaft sy stem, and for the HPT shafts on the other engine models used to show how the reliability calculation is 2.87x10
- 9 failure per flight hour is applicable to the Package C1 models. Ref Question a., 'the 2nd question' as answered b y Iain Park 3/6/14 at 12:59 PM
. Rolls
- Royce provided ratios of stress to ultim ate stress to show the Package C design is in the famil y of historical service engines. Ref. ED MS01000175101 I ss 2 (12/8/13). Please provide the associated actual stress levels and ultimate stress figures that were used for each ratio number provided in the report. Ref Question a., 'the 2nd question' as answered b y Iain Park 3/6/14 at 12:59 PM
. Please provide the part life values in the drive arm areas of the HPC and HPT, and any mini
- disc lives, for the Package C design and the historical service engines. o **Rolls -**  **Royce provided safe lives and stress levels in the HP shaft section for Trent 1000 Package C1, Trent 700, and RB211**  **- 535E4** **engines. The data presented include material, component life cycles, feature life cycles, peak stress, UTS at temperature, pea**  **k stress/UTS at temperature, and temperature at peak stress for**  **critical features.** o **Rolls -**  **Royce provided evidence that failure of the HP Shaft System is Extremely Remote**  **.**  **Prime failure of critical parts is Extremely Remote by definition**  **.**  **Critical part lifin g management continues once the parts**  **are in service .**   **Rolls -**  **Royce provided an HP Compressor Peak Stress Comparison**  **.**  **Rolls -**  **Royce provided an HP Turbine Peak Stress Comparison**  **.** 7. Other questions on EDMS01000175101 and DNS192492 I ss 2 (6 Mar 14)
. Para. 5.5.9 of EDMS01000175101 and para. 9.8 of DNS192492 discuss oil fires and the likelihood that no fire will stabilize in the area between the HP shaft and the IP shaft. Given that the HP shaft geometry and shaft speeds of Package C are different from Package A, please clarify what evidence there is that oil collecting in the HP shaft area of a Package C engine will not result in a fire in the HP shaft area? o **Rolls -**  **Royce provided a detailed explanation for why a fire leads to IPT shaft failure. Rolls**  **- Royce**  **showed development and in -**  **service events on different engine types support that regardless of different**  **HP shaft geometry, shaft speed and air flows, the fire will lead to an IPT shaft failure.**  8. Other questions on EDMS01000175101 and DNS192492 I ss 2 (6 Mar 14)
. Para. 5.5.6 of EDMS01000175101 and para. 9.5 of DNS192492 say that since there is no way

for the HP shaft (drive arms) to rub directly on the IP shaft, there is no threat posed to the HP torque path from contact with the IP turbine shaft. Given that the torque path connects to the HPC disc, HPT disc and mini
- disc, please clarify

what experience you have on the effects of IP shaft to disk (HPC/HPT/mini
- disc) rubbing on the HP torque path? o **Rolls -**  **Royce provided an explanation showing the gap between the**  **IPT shaft and all components on the HP shaft system is too big to allow any contact of IPT shaft on HP torque path.**