# NTSB ENG24FA003: Boeing 767-300F, N287FE, Memphis, TN, October 18, 2023 - Type: NTSB incident investigation - Classification: Incident · No injuries · Class 3 · Field · Final report - Date: October 18, 2023, 16:15 local (21:15 UTC) - Place: Memphis, TN - Coordinates: 35.040031, -89.981873 - Nearby events: https://openairdocs.org/map.md?lat=35.0400&lon=-89.9819&mi=10 - Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping) - Defining event: [Initial climb: Fire/smoke (non-impact)](https://openairdocs.org/ntsb-events/150) - Highest injury: No injuries - Injuries: 3 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Aviation Engineering Division - Parties: FedEx, Boeing, Collins Aerospace, FAA, Honeywell, ALPA, GE - NTSB case key (mKey): 193272 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ENG24FA003 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/193272/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=193272 - Page: https://openairdocs.org/ntsb/ENG24FA003 ## Probable cause A high-pressure fuel leak from a gap in the bolted flange interface between the main fuel pump’s fuel crossover supply tube and the hydromechanical unit idler adapter pad, which resulted in the crossover tube flange bolts partially pulling out and allowing fuel to escape and ignite on contact with the engine’s heatshield. Contributing to the fuel leak was Avio Aero's incorrect manufacture of the idler adapter pad bolt holes, which deviated from GE's manufacturing print requirement; Avio Aero's improper installation of threaded inserts into the idler adapter bolt holes; Avio Aero's failure to inform GE about the manufacturing deviation and request approval; and GE's failure to identify the manufacturing deviation during adapter quality and compliance design reviews. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Engine fuel and control](https://openairdocs.org/ntsb-findings/01057300): Aircraft › Aircraft power plant · Malfunction (probable cause) - [Manufacture/production: equipment manufacture](https://openairdocs.org/ntsb-findings/04013010): Organizational issues › Development · Manufacturer (probable cause) - [Documentation/record keeping](https://openairdocs.org/ntsb-findings/04033000): Organizational issues › Support/oversight/monitoring · Manufacturer (probable cause) ## Analysis The incident engine, a General Electric (GE) CF6-80C2 turbofan, suffered an undercowl fire due to a high-pressure fuel leak originating from a bolted flange interface between a high-pressure fuel crossover tube and the hydromechanical unit (HMU) accessory gearbox adapter pad. The engine’s accessory heat shield surface temperatures and stagnant airflow near the fuel leak location were sufficient to cause ignition. Two threaded inserts in the adapter pad were found protruding and likely prevented the fuel tube from correctly seating on the adapter pad surface. Threaded inserts were not securely installed into the adapter pad, which allowed the crossover tube bolts to partially pull out. Multiple insert holes had stripped threads, linear scoring, counterclockwise material smearing, missing surface anodization, cross-threading, and concave hole profiles. Avio Aero, the adapter manufacturer, implemented an automated pre-tap operation that pre-machined threads into the adapter pad to ease installation of self-tapping steel inserts. In early 2023, this pre-tap operation was determined to be a deviation from the part’s drawing requirements. Neither GE Aerospace nor Avio Aero could find documentation supporting the decision to pre-tap the adapter holes or Avio Aero communicating to GE of their decision to deviate from the print requirement. Avio Aero may have decided to pre-tap the adapter holes because other parts were using this process. ## Factual narrative On October 18, 2023, at about 16:15 Central Standard Time, a FedEx Boeing 767-300F, registration N287FE, powered by two General Electric CF6-80C2 turbofan engines, experienced a No. 1 (left) engine fire during initial climb from Memphis International Airport, Memphis, Tennessee, USA. Upon landing, airport rescue and firefighting observed damage to the No. 1 engine thrust reverser and core cowling, but no indications of an active fire. No fire suppressant was applied to the engine. Ground inspection of the No. 1 engine with the cowls and thrust reverser opened revealed the engine experienced an undercowl fire. The main fuel pump’s (MFP) fuel inlet flange was found fractured and still bolted and attached to the engine’s main fuel supply line. The exposed MFP fracture surface appeared melted (Figure 1). Fractographic analysis confirmed melting and resolidification of the fracture surfaces with no evidence of a mechanical failure mode. Figure 1: Fractured main fuel pump and detached main fuel supply line A small area of coking was found on the hydromechanical unit’s (HMU) idler adapter pad sealing surface where an upper fuel crossover tube attaches (Figure 2). This crossover tube delivers high pressure fuel from the MFP to the HMU and is secured using four bolts installed into threaded steel inserts within the idler adapter. Two of these threaded inserts were found protruding/pulled out from the adapter pad. Figure 2: Idler adapter’s crossover tube mount pad surface Computed tomography scans found three of the four idler adapter bolt holes used to secure the upper fuel crossover tube’s steel inserts had damaged and/or missing threads (Figure 3). The damaged bolt holes did not have sufficient thread engagement to secure the crossover tube to the adapter pad. High-pressure fuel loads likely caused the inserts to partially pull out, resulting in a gap forming between the crossover tube and the idler adapter pad. Figure 3: Thread engagement of inserts No. 2 (left) and No. 4 (right) Review of the idler adapter’s manufacturing requirements found the idler adapter’s bolt holes should be drilled through and then have self-tapping, threaded steel inserts installed into the holes. Review of the incident idler adapter’s manufacturing process found its holes were drilled through and then pre-tapped prior to installing the steel inserts. Investigation found multiple insert holes had stripped threads, linear scoring, counterclockwise material smearing, missing surface anodization, cross-threading, and concave hole profiles, all of which were evidence of improperly installed steel inserts into adapter holes with preexisting threads. Avio Aero initially manufactured the HMU idler adapter at its Brindisi, Italy facility in 1996 and then moved production to their Turin, Italy facility in 2003. According to GE, the idler adapter should have completed a first article inspection (FAI) at the Brindisi facility in 1996, and again at the Turin facility in 2003; however, noFAI documentation from either facility was found. In early 2023, Avio Aero realized they were pre-tapping other non-GE parts that used self-tapping inserts, which were deviations from those parts’ drawing requirements. The idler adapter was found to be one of these parts and Avio Aero removed the pre-tap operation from the adapter’s manufacturing process in August 2023. Avio Aero then notified GE who determined pre-tapped adapter holes violated the adapter drawing requirements. Avio Aero could not produce any documentation showing who authorized the deviation or why the pre-tap operation was incorporated into their manufacturing process. As a result of this investigation, GE Aerospace released Service Bulletin (SB) 72-1648 HMU/MEC Idler Adapter Inspection, Revision 00, on June 28, 2024, requiring repetitive, on-wing shim checks at each insert location and a one-time pull check of installed inserts at the next engine shop visit. The FAA was determining the need to issue an Airworthiness Directive mandating compliance with GE SB 72-1638 at the time of this report. Avio Aero now uses a pneumatic tool to install the adapter’s threaded inserts and added the insert pull-out check to the manufacturing process. GE Aerospace plans to add notes to the next revision of the adapter drawing specifying no prior hole tapping is allowed, pull-out tests must be performed on all installed inserts, and installed inserts must not protrude above the surface. ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Initial climb: Fire/smoke (non-impact)](https://openairdocs.org/ntsb-events/150) (defining event) - [Initial climb: Powerplant sys/comp malf/fail](https://openairdocs.org/ntsb-events/340) ## Aircraft - Registration: [N287FE](https://openairdocs.org/aircraft/N287FE), registered now, S/N 63138, built 2022 (OpenAirDocs) - Reported make and model: BOEING 767-300F - Registry model: [Boeing 767-300F](https://openairdocs.org/model/boeing-767-300f) (registry code 138513G) (OpenAirDocs) - Registry engine: [GE CF6-80C2B6F](https://openairdocs.org/engine/ge-cf6-80c2b6f) (registry code 30109, turbo-fan) (OpenAirDocs) - Category: Airplane - Serial number: 63138 - Year built: 2022 - Engines: GE CF6-80C2B6F 60030 lbs thrust turbo fan; GE CF6-80C2B6F 60030 lbs thrust turbo fan - Damage: Minor damage - Fire: In-Flight - Flight: Part 121 - Operator: Federal Express Corp - Registered owner: Federal Express Corp - Airworthiness certificate: Standard, Transport - Destination: Same as departure - Airport: MEM, Memphis Intl ## Weather - Conditions: Dusk ## Docket (10 files) The files NTSB released with the investigation on April 30, 2025, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=193272. 133 MB in all. - Powerplants group factual report ENG24FA003 (item 1, PDF, 120 pages, 12.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18611417&FileExtension=pdf&FileName=Powerplants%20Group%20Factual%20Report%20ENG24FA003-Rel.pdf - Powerplants attachment 1 - fedex chipcheck analysis (item 2, PDF, 4 pages, 233 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18611427&FileExtension=pdf&FileName=1%20-%20ChipCHECK%20Analysis-Rel.pdf - Powerplants attachment 2 - ge aerospace fohx debris metallurgical analysis (item 3, PDF, 10 pages, 3.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18611902&FileExtension=pdf&FileName=2%20-%20Metallurgical%20Evaluation%20of%20CF6%20FOHX%20Debris%20Sample_02152024-Rel.pdf - Powerplants attachment 3 - Honeywell hmu examination report (item 4, PDF, 31 pages, 4.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18620375&FileExtension=pdf&FileName=3%20-%20Examination%20Report%20of%20HMUs%20-%20Memphis%20TN%20for%20Release_Redacted-Rel.pdf - Powerplants attachment 4 - collins aerospace material project report for mfp housing (item 5, PDF, 41 pages, 18.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18621820&FileExtension=pdf&FileName=4%20-%20Mpr20230667%20-%20Public_Redacted-Rel.pdf - Powerplants attachment 5 - the Boeing company fuel supply hose analysis (item 6, PDF, 20 pages, 3.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18611664&FileExtension=pdf&FileName=5%20-%2019338%20-%20Boeing%20EQA%20Report%20-%202023-10-18%20FED%20767-300F%20N287FE-Rel.pdf - Powerplants attachment 6 - ge aerospace idler adapter metallurgical analysis (item 7, PDF, 119 pages, 69.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18611816&FileExtension=pdf&FileName=6%20-%20Metallurgical%20Evaluation%20Idler%20Adapter_FINAL%20(public%20release)-Rel.pdf - Flight data recorder - specialist's factual report (item 8, PDF, 18 pages, 10 photos, 4.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=17984169&FileExtension=pdf&FileName=ENG24FA003%20-%20FDR%20-%20DOCKET_R2-Rel.pdf - Flight data recorder - attachment 1 (FDR csv data for incident flight) (item 9, CSV, 5.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=17588765&FileExtension=csv&FileName=Attachment%201_ENG24FA003_docket_export-Rel.csv - Flight data recorder - attachment 2 (FDR csv data for previous flights) (item 10, CSV, 9.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=17984642&FileExtension=csv&FileName=Attachment%202_ENG24FA003_docket_export_previous-Rel.csv From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.