NTSB Identification: CHI93IA346.
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Incident occurred Monday, August 30, 1993 in DICKINSON, ND
Probable Cause Approval Date: 10/20/1994
Aircraft: CESSNA 414A, registration: N36990
Injuries: 5 Uninjured.
NTSB investigators used data provided by various sources and may not have traveled in support of this investigation to prepare this aircraft incident report.
THE CORPORATE TWIN-ENGINE AIRPLANE WAS TAXIING FOR DEPARTURE WHEN THE PILOT TURNED THE COCKPIT/CABIN HEATER ON. APPROXIMATELY FIVE MINUTES LATER AN EXPLOSION OCCURRED WHICH CAUSED TWO OF THE THREE BAGGAGE DOORS TO COMPLETELY SEPARATE FROM THE AIRFRAME. A THIRD DOOR REMAINED ATTACHED WITH BY A HINGE. DURING THE ON-SCENE INVESTIGATION EXPLOSION/FLAME DAMAGE TO THE BAGGAGE COMPARTMENT INTERIOR AND THE INTERIOR SIDES OF THE DOORS WAS NOT OBSERVED. INSPECTION OF THE HEATER UNIT REVEALED THE COMBUSTION AIR PRESSURE SWITCH WOULD NOT INTERRUPT ELECTRICAL POWER TO THE FUEL SOLENOID VALVE WHEN AIR PRESSURE WAS REMOVED FROM IT. THE SOLENOID ALLOWED FUEL TO ENTER THE HEATER UNTIL CONDITIONS ALLOWED THE EXPLOSION.
The National Transportation Safety Board determines the probable cause(s) of this incident to be: the total failure of the airplane's heater system combustion air pressure safety switch. Full narrative available
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