(e) If not proceeding to next step, verify that MACH AIRSPEED -GEAR DOWN DISPATCH selector switch is set at NORMAL VMO position.
(4) Test Fuel Tank Airspeed Warning Switch Operation (if installed)
(a)
Verify that MACH AIRSPEED - GEAR DOWN DISPATCH selector is set at NORMAL VMO position.
(b)
On airplanes with supplementary fuel tanks, verify that at least one tank is not empty (Ref 12-11-01).
(c)
Pressurize auxiliary pitot-static system No. 2 (Ref 34-11-00).
CAUTION: TO PREVENT DAMAGE TO INSTRUMENTS AND/OR EQUIPMENT,
_______ OBSERVE ALL CAUTIONS IN PITOT-STATIC SYSTEM -MAINTENANCE PRACTICES.
(d) Apply pressure for each test point listed in following table, and check that warning clacker comes on.
NOTE: Allow at least 10 seconds after fuel level float
____ switch closes before applying pressure.
EFFECTIVITY
ALL 19 Page 503 Apr 25/8634-14-00
STATIC PITOT DIFF. INDICATED TEST ALTITUDE PRESSURE PRESSURE PRESSURE AIRSPEED POINT_____ (FEET) ___________ (IN HG ABS) ___________ (KNOTS)
________ (IN HG ABS) ___________ (IN HG ABS) ________
1 Sea Level 29.921 35.904 - 36.130 5.983 - 6.209 342.0 - 348.0 2 10,000 20.577 26.560 - 26.786 5.983 - 6.209 342.0 - 348.0 3 20,000 13.750 19.733 - 19.959 5.983 - 6.209 342.0 - 348.0 4 30,000 8.885 14.868 - 15.094 5.983 - 6.209 342.0 - 348.0 5 40,000 5.538 9.387 -9.490 3.800 - 3.902 275.7 - 279.2 6 45,000 4.355 7.361 -7.442 2.979 - 3.059 245.2 - 248.4
B. Restore Airplane to Normal
(1)
Return pitot static systems to ambient pressure and disconnect test adapters.
(2)
Remove electrical power if no longer required (Ref 24-22-00).
EFFECTIVITY
ALL 17 Page 504 Dec 25/8634-14-00
TOTAL AIR TEMPERATURE/N1 LIMIT INDICATING SYSTEM -
__________________________________________________ DESCRIPTION AND OPERATION
_________________________
1. General_______
A. The total air temperature/N1 (TAT/N1) limit indicating system computes input data from the CADC, anti-ice, air conditioning and total air temperature systems. The output of the system is a display of total air temperature and engine fan speed (N1) limit allowable under existing conditions. Outputs of N1 limit, total air temperature, and computer valid signals are also provided to the auto throttle system (22-31-00). An output is also provided to the N1 command indicators via the auto throttle computer. The TAT/N1 limit system uses inputs of mach number, coarse and fine altitude from the central air data computer, an input of total air temperature from total air temperature probe No. 1 and an input from the anti-ice and air conditioning systems.
B. The TAT/N1 limit indicating system consists of three components; a computer, an indicator and a combined auto throttle - TAT/N1 mode selector panel (component location is shown in Fig. 1).
C. The A/T-TAT/N1 limit mode selector panel allows N1 limit selection of any one operating mode ranging from takeoff to cruise, alternate N1 limit ratings, N1 limit derating selection and display and selection of auto throttle operating mode. The computer uses inputs from the CADC and the mode panel to compute the maximum attainable engine fan speed (N1) available for the engines at any given time. The TAT/N1 limit indicator displays total air temperature and the computed engine fan speed (N1) in the form of analog readouts.
D. The TAT/N1 limit system has two sources of power. The computer receives 115-volt ac power from essential flight instrument bus and the indicator receives 26-volt ac power from autotransformer No. 3. The system is energized from circuit breakers on panel P7.
2. TAT/N1 Limit Computer (Fig. 1)_____________________
A. The TAT/N1 limit computer is a 3/8 ATR short case and is held in place by a standard cam-lock handle. The computer monitors various analog inputs and automatically calculates the engine fan speed (N1) for current flight conditions. This constantly updated N1 value is then displayed on the TAT/N1 limit indicator and N1 command indicators.
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