Critical Powder Metal Issue - GTF & LEAP-1B Insights

UPDATE DECEMBER 28 - Operators of the Pratt & Whitney PW1100G-JM will likely be confronted with longer delays from engine inspections. The FAA has issued a notice of proposed rulemaking that requires accelerated inspections and replacements of more parts that have been produced from contaminated powder metal. A final rule of a separate Airworthiness Directive also requires inspections of the CFM LEAP-1B. As has been reported before, the powder metal issue affects the High-Pressure Turbine (HPT) stage-1 and stage-2 disks as well as the High-Pressure Compressor (HPC) 7th and 8th stage integrally bladed rotor (IBR). An October 2022 AD addressed the HPT disk issues, but after the failure of the blade rotor, this was followed up by another AD in August this year. Angled ultrasonic inspections (AUSI) were required for the HPT disks and IBR-7 on most sub-versions of the PW1100G-JM that are used on the Airbus A320neo family. In August, cracks have also been found in the HPT disks of the PW1400G series that powers the Russian Irkut MC21. This aircraft hasn’t entered service due to the sanctions imposed on Russia in February last year. When cracks are found, the affected parts need replacement to prevent failure, most likely an uncontained failure with the risk of penetration of the fuselage. These inspections and replacements will result in the grounding of some 650 Geared Turbofan-powered Airbus aircraft in the first months of 2024, with a peak expected in Q1 extending through Q2. Replacing the hubs In the latest Notice of Proposed Rulemaking, the FAA says: “Since the FAA issued AD 2023–16–07 (in August), additional manufacturer analysis found that the failure of the HPC IBR–7 was caused by a powder metal anomaly, similar in nature to the anomalies outlined in AD 2022–19–15 (in October 2022). The analysis also concluded that there is an increased risk of failure for additional powder metal parts in certain powder metal production campaigns, specifically the HPC IBR–7 and HPC IBR–8, and that all affected parts are susceptible to failure significantly earlier than previously determined. The condition, if not addressed, could result in uncontained hub failure, release of high-energy debris, damage to the engine, damage to the airplane, and loss of the airplane.” “This proposed AD would require performing an AUSI of the HPT 1st-stage hub and HPT 2nd-stage hub and replacing as necessary. This proposed AD would also require performing an AUSI of the HPC IBR–7 and HPC IBR–8 for cracks and replacing as necessary. This proposed AD would also require accelerated replacement of the HPC IBR–7, HPC IBR–8, HPC rear hub, HPT 1st-stage hub, HPT 1st-stage air seal, HPT 1st-stage blade retaining plate, HPT 2nd-stage hub, HPT 2nd-stage blade retaining plate, and HPT 2nd-stage rear seal.” The FAA estimates that some 430 engines installed on airplanes of the US registry are affected. Of these, “366 engines will need replacement of the HPT 1st-stage hub, 351 engines will need replacement of the HPT 2nd-stage hub, 408 engines will replacement of the HPC IBR–7. 368 engines will need replacement of the HPC IBR–8, 283 engines will need replacement of the HPC rear hub, and 206 engines will need replacement of the HPT 1st-stage air seal, HPT 1st-stage blade retaining plate, HPT 2nd-stage blade retaining plate, and HPT 2nd-stage rear seal.” While the work may be done during previously planned checks and repairs, additional inspections will likely extend the time of engines in the workshops and delay their return to airlines. The NPRM closes for comments on January 11. CFM LEAP-1B Also on Monday, the FAA issued a final rule for an Airworthiness Directive for the CFM LEAP-1B that powers the Boeing MAX. At issue here too is powder metal contamination, specifically in HPT rotor stage 1-disks and certain compressor rotor stages 6–10 spool. The AD becomes effective on January 16 and follows a notice of proposed rule-making that was issued in July. Affected parts have a lower fatigue life capability due to iron inclusion. This may cause premature fracture and subsequent uncontained failure of certain HPT stage 1 disks and a certain compressor rotor stages 6–10 spool. “In the NPRM, the FAA proposed to require replacement of certain HPT stage 1 disks and a certain compressor rotor stages 6–10 spool and also prohibit the installation of an HPT stage 1 disk or compressor rotor stages 6–10 spool that has a part number and serial number identified in the service information onto any engine.” The FAA thinks only 39 engines in the US register are affected by the issue. They will need to have their HPT stage 1 disks replaced. Already in June 2022, an AD for the LEAP-1A on the Airbus A320neo family also related to powder metal contamination became effective. (UPDATE: the FAA announced on December 28 that it is withdrawing the NPRM. "Since the issuance of the NPRM, the FAA has received information that an error was inadvertently included in the compliance times for some of the HPT 1st-stage and 2nd-stage hubs, which would have required removal significantly later than necessary. Accordingly, the NPRM is withdrawn." The agency issued a new NPRM with the correct compliance times.)

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