First Layer or Improvements:
Measures to Eliminate the Root Cause (prevent internal heating of a cell)

• Adjust the torque appropriately to tighten the nut connecting the electrode
• Improved insulation of cells (wrap with insulation tape)
• Improved insulation at the bottom of the battery case interior
• Improved insulation between cells and between cells and the battery case
• Improved insulation of the upper part of the battery case interior
• Improved insulation of reinforced material of the battery case interior
• Drain holes to address moisture
• Lower the highest charge allowed in the battery monitoring unit and charger
• Stabilize battery charging current
• Improve protective function against over discharge
• More stringent screening of the battery cells after production
• Improve quality control, etc. in the production process

Second Layer of Improvements:
Measures to prevent problems from spreading between cells

• Insulation to isolate cells from each other and from the battery case to resist heat
• Make a gas vent inside the battery case
• Insulation around wiring inside the battery case to resist heat
• A tube to join value valve and vent in lower fuselage

Third Layer of Improvements Measures in the unlikely event of a battery failure
(a new enclosure to prevent trouble from spreading to the cabin)

• Enclose the battery case
• A tube to join value valve and vent in lower fuselage