AD 2003-26-09 Airworthiness Directives; Pratt & Whitney PW4074, PW4074D, PW4077, PW4077D, PW4084, PW4084D, PW4090, PW4090D, PW4090-3, and PW4098 Turbofan Engines

This AD applies to Pratt & Whitney PW4074, PW4074D, PW4077, PW4077D, PW4084, PW4084D, PW4090, PW4090D, PW4090-3, and PW4098 turbofan engines. These engines are installed on, but not limited to, Boeing 777 series airplanes.

You are responsible for having the actions required by this AD performed within the compliance times specified unless the actions have already been done. Credit for Previous Inspections (f) Inspections performed before the effective date of this AD, using AD 2003-22-09 or Pratt & Whitney Alert Service Bulletin (ASB) No. PW4G-112-A72-257, dated June 30, 2003, may be counted toward satisfying the initial and repetitive inspection requirements of paragraphs (g) through (k) of this AD. Borescope Inspection of Engines With High Oil Consumption (g) For engines with high oil consumption that troubleshooting procedures fail to determine the source of oil loss, borescope-inspect No. 3 bearing oil vent tube assembly and or HPT assembly within 100 cycles-in-service (CIS) of the high oil consumption event, using paragraphs (g)(1) through (g)(2) of this AD. Information on troubleshooting engines with high oil consumption can be found in Boeing 777 Fault Isolation Manual (FIM), section 71-05, Task 830. See paragraph (l) of this AD for a definition of high oil consumption. (1) Borescope-inspect the No. 3 bearing oil vent tube assembly for evidence of oil wetting or staining. Follow Step 3, paragraphs 1. through 1.A.(8)(a) of Accomplishment Instructions of Pratt & Whitney ASB No. PW4G-112-A72-257, Revision 1, dated August 22, 2003. (2) If the No. 3 bearing oil vent tube is blocked and attempts to clear it are unsuccessful, borescope-inspect the HPT assembly, following Step 4, paragraphs 1. through 1.B(14) of Accomplishment Instructions of ASB No. PW4G-112-A72-257, Revision 1, dated August 22, 2003. (3) Remove the HPT assembly within 100 CIS of the high oil consumption event if evidence of oil wetting or staining is found in the No. 3 bearing oil vent tube or on the HPT first stage disk. (4) Replace any heat distressed HPT assembly hardware if oil wetting or staining is found. Turbine Exhaust Case (TEC) Inspections Of All Engines (h) Inspect the TEC of all engines, within 500 hours-in-service (HIS) after the effective date of this AD as follows: (1) Visually inspect the TEC in the vicinity of the No. 3 bearing oil vent tube assembly for evidence of oil wetting or staining, using Figure 2 of Pratt & Whitney ASB No. PW4G-112-A72-257, Revision 1, dated August 22, 2003, for location of inspection. (2) If evidence of oil wetting or staining is found at the TEC, borescope-inspect the No. 3 bearing oil vent tube assembly within 100 additional CIS, to confirm the oil is from the vent tube. Follow Step 1, paragraphs 1.B. through 1.D.(8)(a) of Accomplishment Instructions of Pratt & Whitney ASB No. PW4G-112-A72-257, Revision 1, dated August 22, 2003. (3) If the No. 3 bearing oil vent tube is blocked and attempts to clear it are unsuccessful, borescope-inspect the HPT assembly following Step 4, paragraphs 1. through 1.B.(14) of Accomplishment Instructions of ASB No. PW4G-112-A72-257, Revision 1, dated August 22, 2003. (4) Remove the HPT assembly within 100 CIS since performing the visual inspection of the TEC specified in paragraph (h)(1) of this AD, if evidence of oil wetting or staining is found in the No. 3 bearing oil vent tube or found on the HPT first stage disk. (5) Replace any heat distressed HPT assembly hardware if oil wetting or staining is found. Borescope Inspections of All Engines (i) Borescope-inspect the No. 3 bearing oil vent tube assembly of all engines at or before accumulating 600 CIS or 2,000 HIS, whichever occurs first, after the effective date of this AD, as follows: (1) Borescope-inspect the No. 3 bearing oil vent tube assembly for evidence of oil wetting or staining. Follow Step 2, paragraphs 1. through 1.A.(8) of Accomplishment Instructions of Pratt & Whitney ASB No. PW4G-112-A72-257, Revision 1, dated August 22, 2003. (2) If the No. 3 bearing oil vent tube is blocked and attempts to clear it are unsuccessful, borescope-inspect the HPT assembly following Step 4, paragraphs 1. through 1.B.(14) of Accomplishment Instructions of ASB No. PW4G-112-A72-257, Revision 1, dated August 22, 2003. (3) Remove the HPT assembly within 100 CIS since performing the borescope inspection of the No. 3 bearing oil vent tube specified in paragraph (i)(1) of this AD, if evidence of oil wetting or staining is found in the No. 3 bearing oil vent tube or found on the HPT first stage disk. (4) Replace any heat distressed HPT assembly hardware if oil wetting or staining is found. Repetitive Inspections of All Engines (j) Repeat the inspections of the TEC of all engines by following paragraphs (h)(1) through (h)(3) of this AD, at intervals not to exceed 500 HIS since last visual check of the TEC, and disposition the engine as specified in paragraphs (h)(4) through (h)(5) of this AD. (k) Repeat borescope inspections of all engines by following paragraphs (i)(1) through (i)(2) of this AD, at intervals not to exceed 600 CIS or 2,000 HIS since last borescope inspection of the No. 3 oil vent tube, and disposition the engine as specified in paragraphs (i)(3) through (i)(4) of this AD. Definition (l) For the purposes of this AD, high oil consumption is defined as an engine consuming more than 0.5 quarts of oil per hour, as provided in the Boeing 777 FIM. Alternative Methods of

This AD results from the finding of a significant reference error in one of the borescope inspection compliance paragraphs of AD 2003-22-09. This AD also results from reports of engine high pressure turbine (HPT) assembly hardware being damaged as a result of thermal distress from oil igniting after leaking from the No. 3 bearing compartment. We are issuing this AD to prevent thermal distressed HPT assembly hardware from remaining in service, which could result in a cracked HPT stage 1 disk and HPT stage 1-2 air seal and an uncontained engine failure.