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XA MEL - MAINTENANCE PROCEDURE NO. 34-26 ATC TRANSPONDER/
______________________________________________________ XA AUTOMATIC ALTITUDE REPORTING
____________________________ XA XA 1. ____________________________________________
ATC TRANSPONDER/AUTOMATIC ALTITUDE REPORTING XA A. _______
General XA XA The following procedure is applicable when ATC Transponder/Automatic XA Altitude Reporting is inoperative to permit normal aircraft XA dispatchability as required by the B.747 MEL. XA XA B. _________
Procedure XA XA Install a placard "INOP" close to the transfer switch on the control XA panel. Left is system 1 is inop. Right if system 2 is inop. In the XA center if both systems are inop. XA
EFFECTIVITY
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XA MEL - MAINTENANCE PROCEDURE NO. 34-29 LOW RANGE RADIO
_____________________________________________________ XA ALTIMETER
_________ XA XA 1. _________________________
LOW RANGE RADIO ALTIMETER XA A. _______
General XA XA The following procedure is applicable when Low Range Radio Altimeter is XA inoperative to permit normal aircraft dispatchability as required by XA the B.747 MEL. XA XA B. _________
Procedure XA XA Placard affected Low Range Radio Altimeter Indicator "INOP". XA
EFFECTIVITY
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PITOT-STATIC SYSTEM - DESCRIPTION AND OPERATION
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1. General (Fig. 1 and 2)
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A. The pitot-static system senses the dynamic (pitot) and ambient (static) air pressure external to the aircraft and supplies these two pressures to the indicators and control units determining the functions of vertical speed, airspeed, mach number, or altitude.
B. The system consists of four aerodynamically compensated pitot-static probes, two alternate static ports, and pneumatic tubes and hoses which connect these sensors to the various air data equipment. The tubing includes drain fittings, and static source selector valves.
C. Pitot and/or static pressures are supplied to the altitude, airspeed and vertical velocity indicators; cabin differential pressure indicator and cabin pressure controller; airspeed and mach warning switches; flap load relief switch(es); air data computers; flight recorder; elevator feel computer modules, rudder ratio control modules, and to rate controllers on the stabilizer control modules. On ALL FREIGHTERS EXCEPT LH 082; AF 151-154, static pressure is applied to the nose door latch differential pressure switch (Ref 52-31-00). On airplanes with CF6 series engines, static pressure is applied to engine stage cutout altitude switch (Ref 36-11-00). On airplanes with fail-op A/P-F/D, static pressure is also applied to an altitude rate unit. On airplanes with supplementary fuel tanks, pitot and static pressures are applied to fuel tank airspeed warning switch.
D. On LH 011-099; AF 152-199; AZ ALL; SN 351-399; IB 415-499; plus airplanes incorporating SB 77-2060, static pressure is applied to N1 monitor altitude switch.
E. The only power source required is for the heater circuits provided for anti-icing of the pitot-static probes. (Refer to Chapter 30, Pitot-Static and Temperature Probe Anti-Icing.)
2. Pitot-Static Probe (Fig. 1, Sheet 3)
__________________
A. Each of the four pitot-static probes provide one dynamic and two ambient pressure inputs to various pitot static subsystems. The probes are mounted well forward and low on each side of the fuselage.
B. Pitot pressure is sensed through a single pitot opening at the tip of the probe and tied into its respective subsystem inside the airplane through a tube and fitting with an unmarked hexnut.
C. Static pressure is sensed through two independent sets of static ports on the probe and tied into its respective static subsystem inside the airplane through two tubes and fittings with hexnuts marked S1 and S2.
3. Alternate Static Ports (Fig. 1, sheet 3)
______________________
A. Each of the two alternate static ports is an independent sensor of external ambient air pressure. Each port provides one static pressure input to the alternate static system inside the airplane skin.
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