RADAR PRESSURIZATION SYSTEM

Size: px

Start display at page:

Download "RADAR PRESSURIZATION SYSTEM"

Brianne Hunter
5 years ago
Views:

1 RADAR PRESSURZATON SYSTEM GENERAL The AN/ ASQ- 7 system maintains approximate sea level pressure within the receiver-transmitter unit and antenna waveguide assembly of the AN/ APN-59B radar set. ARCRAFT NSTALLATON The system is independent of all other pressurization systems on the airplane. t consists of a control panel, dehydrator, air compressor, and pressure switch. The contro-l panel is on the navigator's panel above the APN-59B radar set control; the dehydrator and compressor are mounted in the forward electrical equipment rack on the right-hand side of the underdeck area, and the pressure switch is located on the right side of th~ nose wheel well next to the APN-59B RT unit. Aircr:lit power for system operation is supplied through circuit breakers on the o::ionics circuit breaker panel above the navigator's statior P<:>we r ~equir eci is 25 colts, DC from \he main D-C a, ioni::s bus number ".):lc. SYSTE:V! OPERATON The pressurization system maintains the density of the air close to that oi air at sea level within the APN-59B RT unit and waveguide assembly. High voltage circuits are located within these units. Spacing of terminals and components is designed for safe operation, based upon the insulating properties of air at sea level pressure. At lower pressures, the insulating ability of air decreases. Between two vol'tage points, therefore, arcing might occur at altitudes. Sea level pressure alone would not be suificient to prevent arcing, since excessive moisture in the air also decreases its insulating ability. For this reason, the air used for pressurization is dehydrated. VOL. V H -1

2 .., : HAV CAT OR 1 S ST.TOH L (~@ t'jmf-' TCS f J RA OAR PR( SS KT CONTOL rall s~ t TCM A l ii NAil ( rwo H ECT CAL [.U r AC < r DCYOATO C ~ P N E N T L C A T N S

3 CRYSTALS AR N (VENT) ~========~====~~~iv.~==~~ PRESSURZED AR DEHYDRATOR 28v DC >-- :.--<( L j COMPRESSOR E H Y D R A T R A N D C M P R E S S R The compressor consists of a vane-type air pump and a D-C motor mounted on the same shaft. The air intake port is connected to the dehydrator. The dehydrator removes any moisture or foreign matter from the air before it enters the pump. The dehydrator is a clear plastic cylinder filied with silica gel dehydrator crystais. A filter pad is installed at each end of the cylinder. The dehydrator crystals are normally de.ep blue in color. As they absorb moisture, their color gradually turns pink. A multicolored humidity indicator label in the cylinder serves as a guide for checking the condition of the cr ystais. W l:e:-~ :he color of the crystais matches the UNSAFE area of the label, the crystals are saturated with moisture and should be replaced. n Pr::E~ sr.r -~!; 1 "A N DC!.st'o T(S T ' ';;b! AV 1'' Ckh i.. NT ARY sus No.1 1 o~.,._: _, 28v :c o orr PADAR NORMALOO--~---~ Rtss., o- 1 PUMP l BLEED P~ SSUR( GAGE SW TCH NAN i folo ~--, "" L J TO RAOAR lit UNT ~'):::::===!=1~ vtn T l"' im'11 COMPRESSOR PUMP R A A R P R E S 5 U R Z A 7 N 5 Y 5 T E M r HY:::>RA T\lR When the system is operating, air is drawn into the compressor from the aircraft cargo compartment. After being compressed, the air is delivered to a common manifold which connects the pressure gauge, pressure switch, and VOL. V l ~ -3

4 radar receiver-transmitter. A check valve, mounted on the compressor air outlet port, pr events the loss of pressure through the compressor when it is stopped. The control panel provides a means of reading syste:. pressure :wd for starting and stopping the compressor. The panel contains a power- controlling RADAR PRESS switch, an absolute pressure gauge, a PRESSURE NDCATOR light, and a J?USH TO BLEED button. Placing the RADAR PRESS switch in the "NORMAL ON" position applies power to the pressure switch. The pressure switch determines when the compressor will run. The switch senses pressure existing in the radar receiver-transmittclr A " ~ "[ s unit and waveguide C N r R L? A N E L assembly. f pressure is less than that of sea level a:mosp here (a;:,)roximately 3 inches of :-:lercury}, contacts of the switch close :1nd s'-'! pply ''olt:tge to t!-:e cc:r.presso::- r:jct:>:. The motor runs until system pressure builds up~"' s::.g h::~ ~, r,; :!'::1 ~. ;; : :: ~?: ~ 3 of mercury. At this time the pressure switch contacts c~ e:::.!:: :h!~ ::::1:-:n<! ~ ~he required s y ste~~ pres ~ ure is autc!"!'la : ic ::t ~ J ;: rr.a :n::lir ~t :;.s ;,;,::::: :.;.: : : ::.\ e:,tenc!i:1g :h!"o;.:.bh the front of r~e pre.s s u!"'e sw i:.c h ~J er~ ::. ~::::.:! ~~. tr:! c-.:. ::::.)f the contacts to be varied fror:l 2-1 to ~2 1 n ~hes of :;.c:-:;;ry.!; ; :: :- :-~:.~. 1y ;.;.r( set to 3.15 inches of mercury. The con.tac!s open when ;>r~ss\c'e is mcrea3e<:! approximately 3. 5 inches of mercury above the prese:!e, el (<!:.ff~rentia: bc:-., ee:: "on and "off" is 3.5 inches of mercury). The "OFF" position of the RADAR PRESS switch deenet gizes :he s ystem. The ":-.1!\'!E;:<;TA.RY ON'' position applies power direc:!y to t!:e corr. pres3or mota:-. T his permits compressor operation to be check~d. T!le?RSSSl'RE :\DCA TOR light glows whenever the compressor is running, regardless of the rr.ethod used to turn the system on. System pressure is continuously indic:tted in inches of mc.rcury (Hg) on the pressure gauge. An adjustable calibration Mask or. t!le face of the gauge is set to the desired pressure ra:jge VOL. V

5 The PUSH TO BLEED button actuates a bleed valve to depressurize the system to the air pressure inside the flight station. MOM MAN DC AVONC BUS eusno.l 28v DC '---~: e r PRESSURE SWTCH - f f CONTROl. PANEL 1 TO ~AO~R ~E C ~ VER-TRANS ~ T T tr A~C ~AVCGU O ASStH8LY SYSTEM,,,,,,.,,~,. :~~ P E R A T N ~ VE:ST,. _. VOL. V 14-5

DESCRIPTION AND OPERATION OXYGEN SYSTEM OXYGEN SYSTEM

DESCRIPTION AND OPERATION OXYGEN SYSTEM OXYGEN SYSTEM 2.20. 2.20.1 EMERGENCY SUPPLEMENTARY OXYGEN WARNING Positively NO SMOKING while oxygen is being used by anyone in the airplane. Keep the entire system free from oil and grease (to avoid the danger of spontaneous