Airworthiness Directive · Amendment 39-17123 · Pratt & Whitney (P&W) Division Turbofan Engines
Pratt & Whitney (P&W) Division Turbofan Engines
This AD applies to the following Pratt & Whitney Division turbofan engines:
(1) PW4000-94″ engine models PW4050, PW4052, PW4056, PW4152, PW4156, PW4650, PW4060, PW4060A, PW4060C, PW4062, PW4062A, PW4156A, PW4158, PW4160, PW4460, and PW4462 including models with any dash number suffix.
(2) PW4000-100″ engine models PW4164, PW4164C, PW4164C/B, PW4168, PW4168A, PW4164-1D, PW4164C-1D, PW4164C/B-1D, PW4168-1D, PW4168A-1D, and PW4170.
We are adopting a new airworthiness directive (AD) for certain P&W PW4000 series turbofan engines. This AD was prompted by reports of 3rd and 4th stage vane fractures in the low-pressure turbine (LPT) of certain PW4000-94" and PW4000-100" turbofan engines. This AD requires dimensional inspections of LPT 3rd stage vanes and the rear turbine case, inspection of LPT 4th stage vanes at the next LPT overhaul and removal of vanes with non-conforming airfoil fillet radii and vanes with more than one strip and recoat repair. This AD also requires disassembly and reassembly of the 2nd stage high-pressure turbine (HPT) rotor and 3rd stage LPT rotor at the next HPT and LPT overhauls. We are issuing this AD to prevent 3rd and 4th stage vane fractures in the LPT, damage to the LPT rotor, uncontained engine failure, and damage to the airplane.
(1) At the next LPT overhaul, do the following:
(i) Remove LPT 4th stage vanes that have a P/N listed in Table 1 to paragraph (e) of this AD from service if more than one strip and recoat repair has been performed.
| 50N174 | 50N674-01 | 51N174-001 | 51N374-001 | 52N574-01 |
| 50N474-01 | 50N774-01 | 51N174-002 | 51N674-01 | 52N674-01 |
| 50N474-001 | 50N774-001 | 51N174-003 | 52N274-01 | 51N774-01 |
| 50N574-01 | 51N174-01 | 51N374-01 | 52N474-01 | 52N774-01 |
(ii) Re-assemble the 3rd stage LPT rotor blades by alternating heavy blades next to light blades and balancing blades of similar weights 180 degrees across the rotor.
(iii) Dimensionally examine index 13 through index 34 of the LPT 3rd stage vane cluster assembly. Use Table 2 to paragraph (e) of this AD and Figure 1, Figure 2, and Figure 3 to paragraph (e) of this AD to determine whether the vane is eligible for installation.
| Inspect: | Eligible for installation limits: |
|---|---|
| 13 | 1.820-1.830 inches (46.23-46.48 mm). |
| 14 | 1.920-1.930 inches (48.77-49.02 mm). |
| 15 | 3.200 inches (81.280 mm) Basic. |
| 16 | 0.900 inch (22.860 mm) Basic. |
| 17 | 0.365 inch (9.271 mm) Basic. |
| 18 | 0.350 inch (8.890 mm) Basic. |
| 19 | 0.160 inch (4.064 mm) Basic. |
| 20 | 0.772 inch (19.609 mm) Basic. |
| 21 | 72° Basic. |
| 22 | 22.382 inch (568.503 mm) Radius—Origin on Plane S Basic. |
| 23 | 21.052 inch (534.721 mm) Radius—Origin on Plane S, concentric with Index 8 Basic. |
| 24 | Angle from Plane S to Plane SL 3°4′37″ Basic. |
| 25 | Angle from Plane S to Plane SM 6°9′14″ Basic. |
| 26 | 90° Basic for typical airfoil section. |
| 27: | |
| Distance from rear foot outer diameter surface to airfoil section along Planes S, SL, and SM | |
| For Section B-B: | 5.241 inches (133.121 mm). |
| For Section E-E: | 3.181 inches (80.797 mm). |
| For Section J-J: | 1.935 inches (49.149 mm). |
| 28: | |
| Airfoil chord at Section J-J (1.935 inches (49.149 mm) from rear foot outer diameter surface at Planes S, SL, and SM) | 1.346 inches (34.188 mm) minimum. |
| At Section E-E (3.181 inches (80.797 mm) from rear foot outer diameter surface at Planes S, SL, and SM) | 1.314 inches (33.376 mm) minimum. |
| At Section B-B (5.241 inches (133.121 mm) from rear foot outer diameter surface at Planes S, SL, and SM) | 1.188 inches (30.175 mm) minimum. |
| 29: | |
| Airfoil thickness at Section J-J (1.935 inches (49.149 mm) from rear foot outer diameter surface at Planes S, SL, and SM) | 0.239 inch (6.071 mm) minimum. |
| At Section E-E (3.181 inches (80.797 mm) from rear foot outer diameter surface at Planes S, SL, and SM) | 0.183 inch (4.648 mm) minimum. |
| At Section B-B (5.241 inches (133.121 mm) from rear foot outer diameter surface at Planes S, SL, and SM) | 0.139 inch (3.531 mm) minimum. |
| 30: | |
| Distance to trailing edge measurement | 0.062 inch (1.575 mm). |
| 31: | |
| Airfoil trailing edge thickness | 0.030 inch (0.762 mm) minimum. |
| 32: | |
| Dimension | 0.315-0.324 inch (8.001-8.230 mm) diameter. |
| 33: | |
| Dimension | 6.785-6.795 inches (172.34-172.59 mm). |
| 34: | |
| Dimension | 0.692-0.714 inch (17.58-18.14 mm). |
(iv) Dimensionally examine index 23 and index 24 of the vane engagement slots on the rear turbine case, where the 3rd stage vane is installed. Use Table 3 to paragraph (e) of this AD and Figure 4 to paragraph (e) of this AD to determine whether the case is eligible for installation.
| Inspect: | Eligible for installation limits: |
|---|---|
| 23 | 1.875 inch (47.625 mm) minimum. |
| 24 | 0.097 inch (2.464 mm) minimum. |
(v) Inspect the 44 LPT 4th stage vane cluster assemblies P/N 52N774-01 for casting identification “51N554AT 1447 2S1C1” and P/N 52N674-01 for casting identification “51N454AT 655 2S1C1.” Remove the vane cluster assembly from service if either of these casting identifications is found.
(2) At the next high-pressure turbine (HPT) overhaul, re-assemble the 2nd stage HPT rotor blades by alternating heavy blades next to light blades and balancing blades of similar weights 180 degrees across the rotor.
After the effective date of this AD, do not install or reinstall into any engine any LPT 4th stage vanes with a P/N listed in Table 1 to paragraph (e) of this AD that are at piece-part exposure and have had more than one strip and recoat repair.
(1) For the purpose of this AD, an HPT or LPT overhaul occurs when all disks in the rotor are removed from the engine and the blades are removed.
(2) For the purpose of this AD, piece-part exposure means that the part is removed from the engine and completely disassembled.
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.
