FAA Issues Airworthiness Directive for GE90 Engines on Boeing 777 Aircraft
The Federal Aviation Administration (FAA) has taken action following General Electric’s (GE) discovery of iron inclusion in GE90 engines, which power Boeing 777 aircraft. The FAA has issued a provisional airworthiness directive, highlighting potential safety concerns associated with this issue.
The FAA issued a proposed airworthiness directive (AD) for certain GE90 engines on Boeing 777 aircraft on September 5, 2023. The proposed AD was prompted by a manufacturer investigation that revealed certain high-pressure turbine (HPT) stage 1 disks, HPT stage 2 disks, forward HPT rotor seals, interstage HPT seals, and stages 7–9 compressor rotor spools were manufactured from powder metal material suspected to contain iron inclusion. This could cause premature metal fatigue and uncontained debris release, which could damage the engine and the airplane. The proposed AD would require replacement of affected parts before further flight. The FAA estimates that the proposed AD would affect nine engines on the US registry and cost about $5 million to comply. The FAA is seeking public comments on the proposed AD until October 20, 2023.
Key Highlights of the FAA’s Directive:
- Iron Inclusion Detected: GE informed the FAA about the detection of iron inclusion in a turbine disk manufactured from the same powder metal material used in certain high-pressure turbine (HPT) parts of the GE90 engine. This includes HPT stage 1 disks, HPT stage 2 disks, forward HPT rotor seals, interstage HPT seals, and stages 7–9 compressor rotor spools.
- Manufacturing Process Deficiencies: The iron inclusion issue is attributed to deficiencies in the manufacturing process. It may result in reduced material properties and lower fatigue life capability, potentially leading to premature fracture and uncontained failure.
- Proposed Rulemaking: The FAA issued a notice of proposed rulemaking (NPRM) to address the problem, inviting stakeholders to comment until October 20, 2023.
- Immediate Actions: GE has already contacted operators of GE90 engines to inform them of the proposed corrective action, which some operators have already taken. The FAA determined that compliance before further flight is necessary.
- Safety Concerns: Failure to address this issue could lead to uncontained debris release, engine damage, and airplane damage.
- Cost of Compliance: The FAA estimated that replacing affected HPT parts, including compressor rotor spools, would cost a total of $2.2 million. Notably, no US-registered aircraft with GE90 engines have affected interstage HPT seals, reducing compliance costs for US-based airlines by $108,936.
The FAA’s directive highlights the importance of addressing this issue promptly to ensure the safety and airworthiness of GE90-powered Boeing 777 aircraft. The agency may take further action based on GE’s investigation findings. The GE90 engine is a significant power plant option for Boeing 777 aircraft, emphasizing the need for thorough safety measures.
FAA directive link: https://www./documents/2023/09/05/2023-18858/airworthiness-directives-general-electric-company-engines
Sources: AirGuide Business airguide.info, msn.com, federalregister.gov, faa.gov