Electrical Loads for Light Single Number of units Total Amperes A. Continuous Load Pitot Heating (Operating) Wingtip Lights Heater Igniter **Navigation Receivers **Communications Receivers Fuel Indicator Instrument Lights (overhead) Engine Indicator Compass Light Landing Gear Indicator Flap Indicator B. Intermittent Load Starter Landing Lights Heater Blower Motor Flap Motor Landing Gear Motor Cigarette Lighter Transceiver (keyed) Fuel Boost Pump Cowl Flap Motor Stall Warning Horn 1 4 1 1-4 1-2 1 2 1 1 1 1 1 2 1 1 1 1 1 1 1 1 3.30 3.00 1-20 1-2 each 1-2 each 0.40 0.60 0.30 0.20 0.17 0.17 100.00 17.80 14.00 13.00 10.00 7.50 5-7 2.00 1.00 1.50 ** Amperage for radios varies with equipment.  In general, the more recent the model, the less amperage required. NOTE: Panel and indicator lights usually draw less than one amp. 17-12 Failure of the pitot-static system may also have serious  consequences for Electronic Flight Instrument Systems  (EFIS). To satisfy the requirements of Title 14 of the Code  Managing a static system malfunction requires that the pilot  know and understand the airplane’s pitot-static system. If a  system malfunction is suspected, the pilot should confirm it  by opening the alternate static source. This should be done  while the airplane is climbing or descending. If the instrument  needles move significantly when this is done, a static pressure  problem exists and the alternate source should be used during  the remainder of the flight. If the pilot should experience a complete in-flight loss of  electrical power, the following steps should be taken: The pilot should remember that the electrically-powered (or  electrically-selected) landing gear and flaps do not function  properly on the power left in a partially-depleted battery.  Landing gear and flap motors use up power at rates much  greater than most other types of electrical equipment. The  result of selecting these motors on a partially-depleted battery  may well result in an immediate total loss of electrical power. conducted in day or at night, in clouds or in the clear. Distance  to nearest suitable airport can also be a factor. If the pilot levels off and then begins a climb, the altitude  indication may still lag. The VSI indicates that the airplane  is not climbing as fast as actual. The indicated airspeed,  however, may begin to decrease at an alarming rate. The least  amount of pitch-up attitude may cause the airspeed needle  to indicate dangerously near stall speed. If the static reference system is severely restricted, but not  entirely blocked, as the airplane descends, the static reference  pressure at the instruments begins to lag behind the actual  outside air pressure. While descending, the altimeter may  indicate that the airplane is higher than actual because the  obstruction slows the airflow from the static port to the  altimeter. The VSI confirms the altimeter’s information  regarding rate of change because the reference pressure is  not changing at the same rate as the outside air pressure. The  airspeed indicator, unable to tell whether it is experiencing  more airspeed pitot pressure or less static reference pressure,  indicates a higher airspeed than actual. To the pilot, the  instruments indicate that the airplane is too high, too fast,  and descending at a rate much less than desired. Partial static system blockage is insidious in that it may go  unrecognized until a critical phase of flight. During takeoff,  climb, and level-off at cruise altitude the altimeter, airspeed  indicator, and VSI may operate normally. No indication of  malfunction may be present until the airplane begins a descent. The source of the pressure for operating the airspeed  indicator, the vertical speed indicator (VSI), and the altimeter  is the pitot-static system. The major components of the pitot- static system are the impact pressure chamber and lines and  the static pressure chamber and lines, each of which are  subject to total or partial blockage by ice, dirt, and/or other  foreign matter. Blockage of the pitot-static system adversely  affects instrument operation.  [Figure 17-10] Pitot-Static System • Shed all but the most necessary electrically-driven  equipment. • Understand that any loss of electrical power is critical  in a small airplane—notify ATC of the situation  immediately. Request radar vectors for a landing at  the nearest suitable airport. • If landing gear or flaps are electrically controlled or  operated, plan the arrival well ahead of time. Expect  to make a no-flap landing and anticipate a manual  landing gear extension. Figure 17-9.  Electrical load for light single.