Go to the text of this page

FY2020 Safety troubles and measures

A summary of past safety troubles and measures


Serious Incident

  • Return to origin after take-off of JAL flight 904 case.

Serious Incident

An incident involving circumstances indicating that there was a high probability of an accident, such as overrunning, emergency evacuation, fire or smoke inside the cabin and abnormal depressurization, encountering abnormal weather conditions, etc, as classified by the Japanese Ministry of Land, Infrastructure, Transport and Tourism (MLIT).

Return to origin after take-off of JAL flight 904 case.


On December 4, 2020, Japan Airlines flight JL904 (Naha Airport bound for Tokyo International Airport) experienced left engine trouble while climing after takeoff and returned to Naha Airport. After landing, the plane underwent inspection, in which engine case damaged and fan blades missing were found on the left engine, and this case was classified as a Serious Incident by Japan Civil Aviation Bureau(JCAB), Ministry of Land, Infrastructure, Transport and Tourism(MLIT).

Emergency measure and Investigation into the cause

The cause will be investigated by Japan Transport Safety Bureau, but as an urgent measure, the fan blades of all 777s equipped with the same type of engine will be visually inspected in detail and the surfaces will be touched to check for any signs of abnormality before departure on December 5 .
JAL Group is providing full cooperation with the investigations.

Immediate recurrence prevention measures

As of December 7, part of fan blades of the engine was found broken. The root cause is now under investigation, but the vibration caused by the breaking of the fan blades, may have caused the fasteners of the left and right engine cowls (covers) to come unhinged during the flight, leading to damage to the cowls.
Therefore, the following measures are being taken for all 18 fan blades on all nine Boeing 777s in operation with the same type of engine (excluding the aircraft in question).

  • A detailed visual inspection and palpation were completed on the morning of December 5 and confirmed no defects. A visual inspection between flights and a detailed visual inspection and palpation at night-time will continue for the time being.
  • Non-destructive inspection(FPI: Fluorescent Penetrant Inspection(*)) has been underway since December 5, and all initial inspection will be completed by December 7. No defects have been found at this time. After the completion of the initial inspection, the same inspection will repeat for every 100 flights for the time being.
    (*) Examination to detect fine scratches that cannot be seen with the naked eye
  • The fan blades of the same type of engine are individually monitored for hours of use and are currently subject to special inspections by the manufacturer every 6,500 flights, based on examples from other companies. In the future, based on this case, blades with more than 3,250 flights since the last special inspection at the manufacturer will be replaced sequentially and special inspections at the manufacturer will be conducted.
To Page top