NTSB Identification: FTW98TA051.
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Incident occurred Wednesday, October 15, 1997 in BRYCE CANYON, UT
Probable Cause Approval Date: 08/16/2001
Aircraft: Cessna P210N, registration: N731NX
Injuries: 2 Uninjured.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this public aircraft accident report.

The pilot said that smoke began coming into the cockpit and 'I could hardly see the propeller.' He stated that 'at that point, we discovered the indicator light for the cabin door seal pressurization pump was on.' The pilot believes that it had been operating continuously due to an air leak in the system. In order to eliminate electrical power to the pressurization pump, the pilot turned the master switch off. After landing the airplane, the pilot located a fire in the upholstery, which he extinguished. Postincident examination revealed that the aluminum housing of a resistor (inverter) in the cabin door seal pressurization pump (an STC modification) had melted and deformed. Further investigation revealed that the pump unit had not been installed properly due to lack of adequate written instructions. Additionally, the design of the unit did not include a pilot controlled on-off switch, adequate space for cooling during operation, sufficient procedural directions for when the amber caution light comes on, and there was no way to monitor the pumps operating time limitation (10 minutes). It was also determined that the wrong amperage fuse had been installed in the pump system.

The National Transportation Safety Board determines the probable cause(s) of this incident to be:

The failure of the resistor (inverter) in the door seal pressurization air pump due to continuous operation. Factors were a failure in the door seal pressurization system, its inadequate design by the manufacturer, its inadequate written instructions for installation and operation, and the installation of the improper electrical fuse by unknown persons.

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