Tuesday, December 18, 2007

Inflight "Emergency"

Today was supposed to be my Final Solo Cross Country. The so called long cross country, because it involves a flight of over 150 miles and landings at three different airports. I had the plans done weeks ago and had gotten canceled several times due to weather or scheduling. Today's weather was nearly perfect for the flight. With all the planning done and the preflight complete I started out from Tipton on the first leg of the trip to Salisbury/Wicomico Regional Airport. Salisbury has a control tower and it's required that one of the airports I visit be tower controlled. About 15 minutes into the flight I was over the Chesapeake Bay and about to cross out of the DC ADIZ. Then I was visited by a gremlin. The Annunciator Panel lit up with the red letters "VOLTS" and I could see that the Ammeter was showing a steady discharge. This meant that the alternator was not providing the airplane with electrical power. The voltage on board was lower than the required 28 volts and the battery was my source of electrical power. Was this an emergency? Yes...and no. The Cessna, like most aircraft has redundant systems. The battery is used to start the engine. Neither the alternator nor the battery supply the power to the engines spark plugs. That is handled by a magneto system that provides the power by moving magnets and the motion of the engine. There are two magnetos each connected to a spark plug for each engine cylinder so the system is redundant.
This means if you lose electrical power the engine will still run. The fuel pump is also engine driven. What will stop? All radios, gps, lighting,transponder, aux fuel pump,electrically powered gauges, Turn Coordinator, and wing flaps. The Cessna has electrically operated wing flaps.

The bottom line is the aircraft would be flyable and able to be landed safely. The proper action to take is reduce the electrical load and terminate the flight as soon as practical.
I did a 180, called approach control, and headed back to Tipton. In hindsight I could have done some troubleshooting in flight but I wanted to be safe and not sorry. After I got back and spoke to the mechanics and an instructor, I went back up in the same plane for some airwork.

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