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The FAA is to release a new Airworthiness Directive on August 22 that requires additional inspections of the Pratt & Whitney PW1100G-JM. This follows the analysis of an incident on an Airbus A320neo in December last year. The issue is related to the powder metal contamination problem disclosed in late July. The AD also applies to the PW1400G-JM used on the Russian Irkut MC-21. Material anomaly requires more Geared Turbofan inspections.
Pratt & Whitney said last month that powder metal contamination on the Geared Turbofan was found on High-Pressure Turbine Stage 1 disks, manufactured between Q4 2015 and Q3 2021. The problem was first identified in March 2020 on an International Aero Engines V2500, which experienced an uncontained engine failure of the HPT stage 1-disk on an Airbus A321.
Back then, the FAA issued an emergency AD within three days of the incident for inspections of the V2500. A separate AD was issued for the PW1100G-JM and various sub-versions in September 2021, as a subsequent investigation by P&W identified a “population” of HPT stage 1 and stage 2 disks that had the same material anomaly attributed to deficiencies in the production process. This was followed by another AD in October 2022, as more engines appeared to be affected.
The latest AD to be released on Tuesday follows another GTF issue that happened on December 24 last year. During the take-off roll, a PW1127GA-JM on an Airbus A320neo experienced a High-Pressure Compressor (HPC) 7th stage Integrally Bladed Rotor (IBR) separation. This resulted in an engine shutdown and an aborted take-off. No reports are known of similar incidents on this part, and no ADs have been released before to address this.
“Following this event, the manufacturer conducted a records review of production and field-returned parts, and re-evaluated their engineering analysis methodology. The new analysis identified HPT 1st-stage hubs and HPT 2nd-stage hubs that are susceptible to failure much earlier than previously determined,” the AD says. Pratt & Whitney issued service information on August 4.
“This AD requires performing an ultrasonic inspection (USI) of the high-pressure turbine (HPT) 1st-stage hub and HPT 2nd-stage hub for cracks and, depending on the results of the inspections, replacing the HPT 1st-stage hub or HPT 2nd-stage hub.”
Irkut
Until now, the material anomaly seemed to be limited to the PW1100G-JM version of the Geared Turbofan. But the new AD identifies a different version for the first time: the PW1400G-JM. This engine has been used on the Irkut MC-21-300 and shares many similarities with the 1100.
“The manufacturer’s updated analysis also identified PW1400G series engines that contain HPT 1st-stage hubs and HPT 2nd-stage hubs that are also subject to this vulnerability and therefore need immediate inspection. This condition, if not addressed, could result in uncontained disk failure, release of high-energy debris, damage to the engine, damage to the airplane, and loss of the airplane.”
The GTF-powered version of the Irkut received the Russian type certificate on December 28, 2021, but the aircraft hasn’t entered commercial service yet. Since Russia started the war in Ukraine three months later and sanctions were imposed on Russia, P&W has severed all ties with the Russian airframer. Irkut continues to develop the MC-21-310 with Russian-made engines and showed the aircraft at the 2021 Dubai Airshow, but this version has not been certified yet.
Remove from service before mid-September
The AD says that only twenty engines are affected in the US, but doesn’t specify numbers outside the US. There is some urgency to have inspections done: “The manufacturer issued service information on August 4, 2023 instructing operators to remove these engines from service by September 15, 2023 due to the urgency of the safety of flight issue. The longer these parts remain in service, without the inspections required by this AD, the higher the probability of failure.”
P&W already had scheduled inspections for September of 200 GTFs that have been identified to have metal powder contamination. The number could be extended to include another 1.000 engines during 2024.
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