ALTERNATOR / GENERATOR FAILURE

Depending upon the aircraft being flown, an alternator failure is indicated in different ways. Some aircraft use an ammeter that indicates the stage of charge or discharge of battery. ( Figure above ) a positive indication on the ammeter indicates a charge condition ; a negative indication reveals a discharge condition. Other aircraft use a load meter to indicate the load being carried by the altenator. ( figure above )

Sometimes an indicator light is also installed in the aircraft to alert the pilot to an alternator failure. On some aircraft such as the cessna 172, the light is located on the lower left side making it difficult to see its illumination if charts are open. Ensure that these safety indicators are visible during flight.

When a loss of the electrical charging system is experienced, the pilot has approximately 40 minutes of battery life remaining before the system fails entirely. The time mentioned is an approximation and should not be relied upon as specific to all aircraft. In addition, the battery charge that exists in the battery may not be full, altering the time available before electrical exhaustion occurs. At no time should a pilot consider continuing a flight once the electrical charging system has failed. Land at nearest suitable airport.

PRECIPITATION STATIC

PRECIPITATION STATIC

Precipitation static, often referred to as P – static, occurs when accumulated static electricity is discharged from the extremities of aircraft. This discharge has the potential to create problems for the instrument pilot. These problems range from the serious, such as erroneous magnetic compass readings and the complete loss of very high frequency ( VHF ) communications to the annoyance of high – pitched audio squealing and St. Elmo’s fire. figure above.

Precipitation static is caused when an aircraft encounters airborne particles during flight ( e.g., rain or snow ), and develops a negative charge. It can also result from atmospheric electric fields in thunderstorm clouds. When a significant negative voltage level is reached, the aircraft discharges it, which can create electrical disturbances. This electrical discharge builds with time as the aircraft flies in precipitation. It is usually encountered in rain, but snow can cause the same effect. As the static buildup increases, the effectiveness of both communication and navigation systems decreases to the point of potential unusability.

To reduce the problems associated with P – static, the pilot should ensure the aircraft’ s static wicks are properly maintained and accounted for. Broken or missing static wicks should be replaced before an instrument flight. Figure below.