The fire appears to have started on the lower-left side of the forward fuselage, just forward of the nose landing gear bay. This area provides access to the equipment bay, where the crew oxygen cylinder is located. It's possible that the crew oxygen cylinder was being replaced by maintenance, but the exact cause has not been confirmed. You can see the ladder to access the hatch. Aviation-grade oxygen requires strict handling precautions. Oxygen-enriched environments can greatly increase fire risk, so personnel must: • Keep hands, clothing, tools, work areas and equipment clean and free of petroleum-based materials. • Keep oxygen away from ignition sources such as heat, sparks and open flames. • Keep oxygen away from flammable materials, fuel, paint thinners, solvents and anything else that can burn. The investigation will determine, for now just my thoughts.