Korean Air Lines Boeing 777 300ER incident
Boeing 777 300ER · Incident: loss of engine power (total) en route
From Chicago O'Hare International Airport (ORD) to Incheon International Airport (ICN)
Event
- NTSB case
- ENG13IA033
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Incident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- Event fatalities
- Unknown
- Ground fatalities
- Unknown
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- Airline
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Unknown
Boeing 777 300ER
- Aircraft type
- Boeing 777
- Category
- Airplane
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- HL8275
- Operator
- Korean Air Lines
- Onboard fatalities
- Unknown
- Route
- From Chicago O'Hare International Airport (ORD), Chicago, ILTo Incheon International Airport (ICN), Seoul
- Aircraft age
- Not recorded
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 129: Foreign
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- En route · cruise
- Defining eventThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- Loss of engine power (total)
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- None
Cause areas
- Aircraft › Aircraft power plant
Not plotted · Location withheld: coordinates are missing, conflicting, invalid, or have no accepted acquisition method. No substitute location has been invented.
NTSB narrative
On July 2, 2013, a Korean Air Lines (KAL) Boeing 777-300ER, registration number HL8275, powered by two General Electric (GE) GE90-115B turbofan engines, experienced a No. 1 engine (left) in-flight shutdown (IFSD) while crossing the Bering Sea. The pilots diverted the airplane to Ugolny Airport (DYR), in Siberia, Russia where an uneventful single engine landing was made. The Korean ARAIB requested delegation of the investigation and the NTSB accepted responsibility for investigating this incident. Post landing examination of the No. 1 engine revealed that the radial gearshaft within the transfer gearbox housing was fractured. Metallurgical examination of the radial gearshaft found an 0.049-inch axial crack with striation features indicative of fatigue propagation and a morphology consistent with initial fatigue initiation occurring under a torsional and/or biaxial stress condition. This axial crack was considered the primary crack and the fracture origin area. Microhardness tests near the fracture origin revealed a reduction in near surface hardness (lower hardness values than required). GE concluded that the near surface low hardness was attributable to decarburization due to marginal (thin or detached) copper plating existing on the gearshaft surface during the hardening process. Through computer modeling and testing of the radial gearshaft, GE concluded that the initiation of the axial crack was likely the result of a combination of high residual tensile stresses produced by local decarburization coupled with the operating stresses experienced at the outer diameter surface. To address the manufacturing process deficiency, GE issued seven service bulletins to remove, inspect, and repair the suspect radial gearshafts. To expedite the removal of the suspect radial gearshafts, the Federal Aviation Administration issued three separate Airworthiness Directives (AD). According to GE, all affected radial gearshafts addressed by the various FAA ADs have been removed from service.
Probable cause
The failure of the transfer gearbox resulting from the fracture and separation of the radial gearshaft from fatigue cracking as a result of a combination of high residual tensile stresses produced by local decarburization during the manufacturing process coupled with the normal operating stresses.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record ENG13IA033
- Event ID
- 20130715X90030
- Case number
- ENG13IA033
- Dataset
- full-current
- Source SHA-256
- 5cf380f0061817c0331a6b2d8cc7e0ee3a79bea469a1001dc5c10e56f35f5ab3
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: investigation status, damage. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: 40e47bb81ae66f5834285f9fe3b140b95d8a0930b528aad3ac087bfedbd0d2b4; retrieved 2026-09-15T22:13:32.483Z.