Incident Overview
An emergency medical services (EMS) helicopter was destroyed by fire while parked at a hospital heliport. The helicopter had recently returned from a medical evacuation flight, during which the on-board patient oxygen pressure had become low. No flight crew was present at the time, and there was no intent for flight during this operation.
Oxygen Refill Operation
Two respiratory therapists participated in refilling the aircraft's oxygen system. The system is serviced via a rear baggage compartment accessed from outside the helicopter. According to the attendants, after making the connection and partially opening the valve, a fire erupted near the connection point.
Post-Fire Observations
Following the fire, one of the therapists recalled the presence of oil above the baggage door. That area of oil had not been wiped clean before the fill operation commenced. Subsequent testing of the valve revealed significant leaking at the connection. A wrench was required to separate the components for inspection. The inspection found no evidence of debris or distortion in the threaded portion of the connection.
Investigation
The investigation did not provide a stated probable cause. The circumstances point to the oxygen refill process, but the source did not explicitly attribute the fire to any specific factor.