# NTSB DCA24LA079: Boeing 747-87UF, N859GT, Miami, FL, January 19, 2024 - Type: NTSB incident investigation - Classification: Incident · No injuries · Class 3 · Limited · Final report - Date: January 18, 2024, 22:34 local (Jan 19, 2024, 03:34 UTC) - Place: Miami, FL - Coordinates: 25.786095, -80.314838 - Nearby events: https://openairdocs.org/map.md?lat=25.7861&lon=-80.3148&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute-climb to cruise: Fire/smoke (non-impact)](https://openairdocs.org/ntsb-events/150) - Highest injury: No injuries - Injuries: 6 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Major Investigations Division - Parties: Atlas Air, FAA, GE Aerospace, Boeing - NTSB case key (mKey): 193682 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DCA24LA079 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/193682/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=193682 - Page: https://openairdocs.org/ntsb/DCA24LA079 ## Probable cause Maintenance personnel’s improper installation and inspection of the port M borescope plug, which resulted in an engine fire. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Maintenance: installation](https://openairdocs.org/ntsb-findings/02062035): Personnel issues › Task performance · Maintenance personnel (probable cause); cases with it: [Boeing 747-87UF, 1 case](https://openairdocs.org/ntsb-findings/02062035/cases.md?model=13848GA), [All aircraft, 371 cases](https://openairdocs.org/ntsb-findings/02062035/cases.md) - [Inspection: post maintenance inspection](https://openairdocs.org/ntsb-findings/02061515): Personnel issues › Task performance · Maintenance personnel (probable cause); cases with it: [Boeing 747-87UF, 1 case](https://openairdocs.org/ntsb-findings/02061515/cases.md?model=13848GA), [All aircraft, 57 cases](https://openairdocs.org/ntsb-findings/02061515/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Enroute-climb to cruise: Fire/smoke (non-impact)](https://openairdocs.org/ntsb-events/150) (defining event); cases with it: [Boeing 747-87UF, 1 case](https://openairdocs.org/ntsb-events/150/sequence.md?model=13848GA), [All aircraft, 504 cases](https://openairdocs.org/ntsb-events/150/sequence.md) ## Analysis During the airplane’s initial climb after departure, the flight crew received engine overheat and fire warning indications for the No. 2 engine. The engine was subsequently shut down, one fire bottle was discharged, and the engine fire light extinguished. After declaring a mayday, the flight returned to the airport and made an uneventful landing. A review of the airplane’s maintenance records revealed that, 4 days before the flight, the airplane had undergone a borescope inspection of the No. 2 engine performed by a third-party vendor. The inspection required the removal of the port M borescope plug. The maintenance work card provided instructions for properly reinstalling the borescope plug to ensure that the locking feature was properly engaged. By initialing the work card, the technician who performed the work and the inspector who reviewed the work indicated that this task had been completed in accordance with the maintenance manual procedure. A postincident inspection of the No. 2 engine revealed that the engine cases were intact with no evidence of an uncontained engine failure. The inspection also revealed burn through of the thrust reverser fan duct fixed inner wall located directly over the combustor diffuser nozzle (CDN) port M borescope plug. The CDN case port M borescope plug was not secured in the engine case and was found loose in the engine cowling. The open CDN port allowed hot gases to escape from the engine, which caused thermal damage to the thrust reverser. A postincident inspection of the port M borescope plug revealed no anomalies to the plug’s material composition, dimensions, threads or locking components. The plug was threaded into an exemplar engine without binding or stiffness and locked as designed. Although the work card had been initialed by a technician and an inspector, it is likely that the port M borescope plug was not properly secured and inspected according to maintenance manual procedures and that the improperly secured plug resulted in the engine fire. ## Factual narrative On January 18, 2024, Atlas Air flight 3885, a Boeing 747-87UF, N859GT, sustained minor damage as a result of a No. 2 (left inboard) undercowl engine fire after departure from Miami International Airport (MIA), Miami, Florida. The five occupants aboard the airplane were uninjured. The international cargo flight was conducted under Title 14 Code of Federal Regulations Part 121 and was destined for Luis Munoz Marin International Airport (SJU), San Juan, Puerto Rico. The flight crewmembers reported that, after departure, while the airplane was passing through an altitude of about 3,000 ft mean sea level (msl), they received an OVHT ENG 2 NAC [overheat engine No. 2 nacelle] caution message followed by a FIRE ENG 2 warning message on their engine indicating and crew alerting system displays. Simultaneously, the fire warning light illuminated, and the fire bell sounded. The captain declared a mayday with air traffic control, and the flight was cleared back to MIA via radar vectors for a landing on runway 9. The crew completed the electronic non-normal checklist and shut down the No. 2 engine. One fire bottle was discharged, and the fire warning light subsequently extinguished. The airplane made an uneventful three-engine landing, and the airplane was met by firefighting personnel, who subsequently cleared the airplane to taxi under its own power to the parking location. A review of the airplane’s maintenance records revealed that, on January 14, 2024, the airplane underwent a borescope inspection of the No. 2 engine, a General Electric (GE) GEnx-2B67 engine. The inspection, performed by a third-party vendor, required the removal of the port M borescope plug; see figure 1 for the location of port M. Figure 1. Engine diagram with port M depicted in the combustor diffuser nozzle (Source: General Electric). The maintenance work card provided instructions on how to properly reinstall the borescope plug to ensure that the locking feature was engaged. The locking design on the borescope plug incorporated a plug cap that utilizes fingers, detents, an internal spring, and a locking slot, as shown in figure 2. When properly installed with the locking slot engaged on the engine, case friction is generated by the fingers and detents, and the plug would be prevented from backing out. The work card was initialed by the technician who performed the work and an inspector who reviewed the work. Initialing a maintenance item indicated that the task was completed in accordance with the maintenance manual procedure. Figure 2. Exemplar borescope plug (Source: General Electric). A postincident inspection of the No. 2 engine revealed burn through of the thrust reverser fan duct fixed inner wall (see figure 3). The engine cases were intact with no evidence of an uncontained engine failure. The combustor diffuser nozzle (CDN) case port M borescope plug was not secured in the case and was found loose in the engine cowling. The burn-through observed on the thrust reverser wallwas directly above the open CDN port M. The engine low pressure spool (N1) and high pressure spool (N2) rotated smoothly with manual rotation. A borescope inspection through CDN port M was performed, and no combustor damage was visible. A review of quick access recorder, flight data recorder, and continuous engine operating data showed no evidence of engine failure or surge/stall. Figure 3. Burned area above borescope port M (Source: Atlas Air). A postincident inspection of the port M borescope plug (see figure 4) revealed general debris and oxidation. The plug’s geometry/features conformed to the drawing requirements with no anomalies noted to the plug’s threads and its locking components. The plug’s materials and coatings were consistent with the design requirements. The plug was threaded into an exemplar engine without binding or stiffness, and the locking feature engaged as designed. Figure 4. Borescope plug recovered from the incident airplane (Source: General Electric). ## Aircraft - Registration: [N859GT](https://openairdocs.org/aircraft/N859GT), registered now, S/N 62441, built 2015 (OpenAirDocs) - Reported make and model: BOEING 747-87UF - Registry model: [Boeing 747-87UF](https://openairdocs.org/model/boeing-747-87uf) (registry code 13848GA) (OpenAirDocs) - Registry engine: [GE GENX-2B67](https://openairdocs.org/engine/ge-genx-2b67) (registry code 30234, turbo-fan) (OpenAirDocs) - Category: Airplane - Serial number: 62441 - Year built: 2015 - Airframe hours: 36468 - Engines: GE GEnx-2B67/P 66500 lbs thrust turbo fan; GE GEnx-2B67/P 66500 lbs thrust turbo fan; GE GEnx-2B67/P 66500 lbs thrust turbo fan; GE GEnx-2B67/P 66500 lbs thrust turbo fan - Damage: Minor damage - Fire: In-Flight - Flight: Part 121 - Operator: Atlas Air Inc - Registered owner: Atlas Air Inc - Airworthiness certificate: Standard, Transport - Last inspection: Continuous airworthiness, January 18, 2024 - Destination: Carolina, PR - Flight plan: IFR - Equipment: ADS-B, Stall warning system, Satellite tracking device, Onboard weather, Electronic primary flight display, Electronic multifunction display, Electronic flight bag or handheld device, Data recorder, Auto-pilot, Angle of attack indicator ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 54; injuries: none; airline transport; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, with waivers/limitations; last flight review June 6, 2023; seat: left; restraint: 5-point; flight hours: 3,791 in this make and model - Co-pilot; injuries: none; airline transport; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, without waivers/limitations; last flight review August 13, 2023; seat: right; restraint: 5-point; flight hours: 3,182 in this make and model - Other flight crew; airline transport; seat: center; restraint: 5-point ## Weather - Conditions: Visual (VMC), Night - Wind: 100° at 13 knots - Visibility: 10 statute miles - Lowest ceiling: 10,000 ft broken - Temperature: 79 °F, dew point 70 °F - Altimeter: 30.15 inHg - Observed at: KMIA, 1 nm away - METAR: KMIA 181553Z 10013KT 10SM SCT018 SCT025 BKN100 26/21 A3015 RMK AO2 SLP210 T02560211 ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Incident 20240119001949I](https://openairdocs.org/incident/20240119001949I), Jan 19, 2024: Boeing 747-87UF, Miami, FL, Minor damage. [privacy data omitted], A Boeing 747-87UF sustained an inflight engine fire following departure from Miami International Airport (mia), Miami, Florida. The… ## Docket (4 files) The files NTSB released with the investigation on October 16, 2024, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=193682. 12.4 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 19 pages, 5.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=17407832&FileExtension=pdf&FileName=6120%20dms_Redacted-Rel.pdf - Flight crew statements (item 2, PDF, 1 page, 83 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=17405777&FileExtension=pdf&FileName=Flight%20Crew%20Statements-Rel.pdf - Metallurgical investigation report - borescope plug (item 3, PDF, 20 pages, 3.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=17450814&FileExtension=pdf&FileName=AvEng-556233A%20GEnx%20959289%20borescope%20plug%20(prop%20rem)_Redacted-Rel.pdf - Statement of party representatives to NTSB investigation (item 4, PDF, 3 pages, 2.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=17450928&FileExtension=pdf&FileName=Party%20Forms%20DMS_Redacted-Rel.pdf From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; 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.