User`s Manual
Contents
1. If vacuum pump is separate item O QO y Ba connect to vacuum circuit usinga OO tee Connect the interface circuit board or other suitably powered ae D connector to the altimeter TE CA Apply DC power while pressing q and holding the MODE switch in 7 E L Release MODE switch when D Oa OFFSET altimeter LEDs go off GAIN Some components are omitted for clarity Others may only be present with options NOTE The above action places the altimeter in its ABSOLUTE PRESSURE mode and is used for calibration purposes If the MODE switch is inadvertently pressed afterwards power will have to be removed and the above repeated to invoke the ABSOLUTE PRESSURE mode again di 10 11 12 13 14 Verify that the altimeter initially displays cold then after about one minute enters the ABSOLUTE PRESSURE mode This is indicated by the PRESSURE legend on the LCD and the fact that the UP DN switch has no effect Allow the instrument to warm up for ONE HALF HOUR THIS IS EXTREMELY IMPORTANT A full and thorough warm up is required for proper adjustment Pump the vacuum to about 11 inHg absolute Wait for altimeter reading to stabilize then adjust the OFFSET potentiometer until the altimeter and STANDARD read the same Release the vacuum and wait for altimeter reading to stabilize Adjust GAIN potentiometer until the altimeter and STANDARD re2. The two previous adjustments are interactive Repeat as necessary until both require no further adjustment This completes the calibration Paint the GAIN potentiometer screw with RED paint or nail polish Shut off DC power and disconnect the interface circuit board connector Install the electronics assembly back into the case and secure with Philips screws Be sure that the board is properly seated in the card slots on either side of the case S196
3. Density altitude is not an altitude either it s an air density If we say that the density altitude is 6500 feet we re saying that the air density is the same as what would normally be experienced at 6500 feet How do we determine pressure and density altitude For pressure altitude all that is required is to know the pressure at sea level on a standard day which is 29 92 inHg or 1013 mBar If we enter this value as the barometric reference for the altimeter we are basically fooling the instrument into thinking it s a standard day The altimeter then indicates pressure altitude Density altitude is more involved It is related to temperature and pressure altitude by a very complex formula The usual approach is to use a chart or slide rule such as the E6B flight computer or its electronic equivalents The inputs in each case are pressure altitude and temperature Aircraft performance parameters such as climb rate take off distance and maximum take off weight are all very dependent on air density For this reason performance curves published in the Flight Manual for each aircraft are given in terms of density altitude or pressure altitude and temperature OVEN WARM UP As mentioned previously the pressure sensor is the heart of the system and must be held at a controlled and elevated temperature to achieve the required system accuracy As such it is housed in a precisely regulated oven and needs sufficient time to reach uniform operating
4. temperature After the cold LCD warning first disappears the displayed and reported altitudes are typically about 100 feet low well within the FAA specification of 125 feet for MODE C encoders After 20 30 minutes this error diminishes and approaches zero This behavior is due to the fact that we started out with a cold oven Although the oven indicates that it s at operating temperature the pressure sensor takes much longer to reach temperature and fully stabilize It s like putting a turkey in a cold oven then turning the oven up to 400 F After only a few minutes the oven will indicate that it s at 400 but the turkey will take hours before it is uniformly heated to that temperature The sensor lag time isn t as extreme as this example but the concept is the same This performance is typical of blind MODE C encoders and we don t object to this initial error because we usually aren t even aware of it In the case of an altimeter with a display however the discrepancy becomes obvious and we are led to believe that the unit is out of calibration it s not age We re used to mechanical altimeters which require no warm up and give their rated accuracy at all times If we are sitting at an airport that has a known elevation of 200 and we set the altimeter to the current barometric pressure the altitude usually reads exactly 200 If it doesn t we pull the set knob out and calibrate it In the case of the electronic altimeter this in
5. 0 of WINDOW 4 and the audio warning will also stop if not already silenced manually In a like manner if you exceed 100 of the WINDOW the red LED flashes and the audio warning tone sounds even if it had been silenced after crossing the 70 threshold The sound is the same as there is no audio distinction between the 70 and 100 thresholds The ALERT LED will return to flashing yellow if the altitude is adjusted to less than 100 of WINDOW and will go back to solid green once within 70 If the audio had not been manually silenced it will also automatically stop at this point but it is more typical to do it manually to prevent it from masking audio communications Pressing and holding the MODE switch from any of the ALERT modes returns the instrument to the regular ALTITUDE mode as shown in the flow chart While in any of the operating modes the OXYGEN LED will illuminate continuously if altitude exceeds 12 500 feet to warn that oxygen is required ELECTRICAL CONNECTIONS Gold plated pins protrude from the back of the case and all electrical connections are through this plug Odd numbered pins are on the bottom and even on top see Fig 2 A termination board with mating connector is supplied with all units and is oriented as shown then pushed on until fully seated This provides a handy method to strain relieve all wires It is supplied with wires for DC power and backlighting and others must be added as needed Solder pads are
6. 2002 01 06 User s Manual Series 2000 Altimeter A S ALTITUDE BARO CLIMB RATE OAT Congratulations on your purchase of the Taskem in He FEET Series 2000 altimeter P L E A S E take a few moments to read this manual thoroughly so you will get the most out of your purchase The Series 2000 is an all solid state highly advanced design which provides accurate ft min ALTITUDE CLIMB RATE and ALTITUDE ALERT ue een HODE functions in a simple to operate format It includes an G et adjustable calibrated Kollsman window that can also serve DN as a barometer when not in flight The Model 2000 B 4 pressure reference is in inches of mercury inHg and the 2 Sey coe E ar d Model 2001 is in millibars mBar Options include a Outside Air Temperature OAT and Density Altitude in i addition to a Mode C encoder output All data is presented on an easily readable liquid crystal display LCD which is backlighted for night viewing Light emitting diodes LED and custom LCD legends alert the operator to various modes and warnings The instrument can be directly operated from standard 14 or 28V aircraft power without any changes or modifications All power and outputs are via a connector that protrudes from the back of the instrument case You can power the instrument now if you would like to try each of the modes and features as you read along Connect a source of 11 to 35 VDC power with positive to the RED wire and negative to BL
7. ACK see Fig 2 page 5 These wires are protected for polarity reversal but APPLYING POWER TO OTHER PINS CAN CAUSE PERMANENT DAMAGE Two standard 9V alkaline batteries provide a convenient source of 18V portable power for operation on the kitchen table When installed in the aircraft it is typical that the instrument will be powered only when the MASTER switch is on Current drain is quite low averaging less than 80 milliamps and never exceeding 360mA so a 1A circuit breaker is more than adequate When power is first applied all visible indicators are turned on in order to test them All 4 LEDs should light and the LCD should appear as shown at left below Note that one of the segments in both the left and rightmost digits are missing this is normal as they are not used After a few seconds the LEDs will go out and the LCD should read cold as shown in the figure below This indicates that an internal oven has not yet reached operating temperature The oven contains the pressure sensor the heart of the instrument and must be held at an elevated and regulated temperature to isolate it from normal ambient variations Note that while the oven is cold none of the switches have any effect and no outputs are available at the external connector dHHAU co id DENSITY PRESSURE ALTITUDE CLIMB LCD segment test oven below temperature After about minute the oven will reach operating temperature an
8. ATE 1 mode 2 mode 3 mode Now momentarily press the MODE switch once more to enter the CLIMB RATE mode The display should read zero but as before if the oven temperature hasn t yet stabilized you could get non zero readings until the oven settles The climb rate is displayed in increments of 50 feet minute Note that the UP DN switch has no effect in this mode and this will be the case in any other situation where it doesn t apply Press the MODE switch once more and the instrument returns to the PRESSURE REFERENCE mode If you did set the altimeter to your known altitude the instrument now indicates the current barometric pressure at sea level just as a Standard barometer does These are the three main modes and the instrument continuously cycles through each as the MODE switch is pressed Other modes and how to get to them are described next Figure on the following page shows how the instrument is sequenced from one mode to the next It s called a flow chart and may look complicated at first but it s not It s really very simple to understand and once you learn the reasoning behind it is easy to remember too The names of each mode are contained within the oval shapes and arrows connecting the different modes represent the action of pressing the MODE switch If the arrow is not labeled it s a normal momentary press of the switch On the other hand if the arrow is labeled 2S this means that the MODE switch is pushed and not released
9. ad the same The two previous adjustments are interactive Repeat as necessary until both require no further adjustment Press the MODE switch once to enter the PRESSURE REFERENCE mode Disconnect vacuum tubing then verify pressure reference setting by performing BARO SET steps 2 through 4 and adjust if necessary This completes the calibration Paint the GAIN potentiometer screw with RED paint or nail polish Shut off DC power and disconnect the interface circuit board connector Install the electronics assembly back into the case and secure with Philips screws Be sure that the board is properly seated in the card slots on either side of the case ll Using STANDARD altimeter Equipment required 10 1 p 12 13 14 15 a STANDARD altimeter capable of displaying altitude in feet and accurate to 20 feet over a range of 1 000 to 30 000 feet b Hand operated vacuum pump if not built into STANDARD altimeter c 14VDC power source capable of 400 mA Shut off power and remove the interface circuit board connector from the back of the instrument At back of instrument disconnect static port plastic tubing Using a 1 Philips screwdriver carefully remove the two screws from the front face Push on the circuit board extending from the back of the case then remove the electronics assembly Connect tubing from STANDARD to pressure port on back of altimeter using plastic tubing and size a
10. agraphs describe the data structure and format The description is very detailed and assumes a working knowledge of electronics and computers The average user will typically have no interest in this and is encouraged to skip this section The data rate is fixed at 9600 baud with one stop bit 8 data bits and no parity A field of 9 bytes containing all data is output every 0 6 seconds with no handshaking Although the data structure conforms to the RS 232 format the logic levels do not Outputs levels are 5V CMOS with an added 10KQ series resistance As such it can not drive long cables and load capacitance should be kept under 2000pF If true RS 232 levels are required Maxim Corp or Linear Technology offer several 5V to RS 232 level converters which can be operated from a single power supply The data format is shown in Figure 3 All values are in two s compliment signed binary Altitude pressure altitude and density altitude are encoded in 16 bits with 1 LSB 1 foot For example 1AD8h 6 872 feet and FCCSh 827 feet Although displayed values are rounded to the nearest 10 feet 100 for density altitude serial data is not This is not to say that serial data has a foot resolution It will typically change in increments of 5 feet or more depending on altitude Outside air temperature is 8 bits with 1 LSB equal to 1 C Examples are 1Eh 30 C and E3h 29 C If the temperature density altitude option is not installed or a temperatu
11. al The wire must be unsoldered and connected to pin 1 for operation from 28V Do not apply power to both pins at the same time A small 20KQ rheostat can be connected in series for brightness control DC POWER DC power to operate the instrument is applied to pins 3 and 4 Pin 3 is GROUND and connects to the negative terminal Connect pin 4 to positive in the range of 11 to 35 volts Note that all ground and shield pins 3 7 9 11 14 amp 26 are internally tied together AUDIO Connect shielded wire to auxiliary audio intercom input as listed above SERIAL DATA Serial data is available at pin 10 Use twisted pair to minimize capacitance Connect the twisted pair return wire to pin 9 TEMPERATURE PROBE If this option is installed connect probe wires as listed above See instructions supplied with OAT density altitude option MODE C All Mode C connections are via pins 14 through 26 Refer to detailed instructions supplied with the Mode C option SERIAL DATA The serial data output provides the means to send all Series 2000 data to other instruments and systems Typical of these are autopilots recorders flight computers and any other device that can make use of altitude pressure altitude density altitude OAT or climb rate information For instance an air speed indicator may make use of this data to compute true airspeed Without this information it would only be capable of displaying indicated airspeed The following par
12. d hold the MODE switch while in either OAT or DENSITY ALTITUDE ui We Jcuu PRESSURE ALTITUDE DENSITY ITUDE PRESSURE OAT mode DENSITY ALTITUDE mode ALTITUDE mode Next are the altitude ALERT modes and since they are concerned with maintaining a nearly constant altitude are accessed from the ALTITUDE mode Press and hold the MODE switch to enter the ALERT SET ase ere mode The instrument should appear as shown at left in the next set of figures Note that the green ALERT LED is on and the altitude legend and value 200 appears on the LCD NG alll es un Lf O Wy QZ NS O wr Nd Nd FO cull Hob E E Be ayy Be g Eri E Be ALTITUDE ALERT SET ALERT ALTITUDE ALERT DELTA mode mode mode The ALERT SET mode establishes the TARGET altitude and the deviation above or below that altitude that will be allowed On entering this mode the current altitude rounded to the nearest 100 feet is established as the TARGET Thus if the altitude just prior to entering the ALERT SET mode was 5230 feet the TARGET would be set to 5200 Likewise an altitude of 8660 would result ina TARGET of 8700 portrayed above The TARGET value is not adjustable and can only be set as just described You must climb or descend to within 50 feet of the desired altitude THEN enter the ALERT SET mode to set it properl
13. d the unit will enter its first mode PRESSURE REFERENCE shown at left in the drawings on the following page This is the barometric pressure em reference currently being used to determine altitude The LCD legend PRESSURE will illuminate to indicate this and the value will be set to the last used pressure reference Pushing the UP DN switch can then change the reference Each momentary operation of this spring loaded switch will change the display by 0 01 inHg or 1 mBar while pushing and holding the switch in either position will change the readings rapidly Momentarily press the MODE switch once and the instrument will enter its second mode ALTITUDE as indicated by the LCD legend in the center drawing At this point you may see some small variations in the displayed altitude until the oven temperature stabilizes It takes less than a minute for the oven to reach operating temperature but several minutes more for it to stabilize and give fully accurate readings Oven warm up details are provided in a separate paragraph Using the UP DN switch change the displayed altitude What you re actually doing is changing the barometric pressure reference again but this time while looking at its effect on computed altitude If you know your current elevation set the displayed altitude to that value 2992 J40 5 para Va anl PRESSURE ALTITUDE CLIMB PRESSURE REF ALTITUDE CLIMB R
14. dapters as required If vacuum pump is separate item connect to vacuum circuit using a tee Connect the interface circuit board or other suitably powered connector to the altimeter Apply DC power and verify that the altimeter initially displays cold then after about one minute enters the PRESSURE REFERENCE mode This is indicated by the PRESSURE legend on the LCD and a numeric display of 29 92 or 1013 depending on model Allow the instrument to warm up for ONE HALF HOUR THIS IS EXTREMELY IMPORTANT A full and thorough warm up is required for proper adjustment Obtain the current sea level barometric pressure from a reliable source ATC tower ATIS ASOS etc Note that ATIS tapes are typically updated at 45 minutes after the hour and diminish in accuracy as they age ASOS data where available is updated every minute and is always current as is the ATC tower Set the STANDARD altimeter to the pressure reference obtained in previous step Also using the UP DN switch set the altimeter under test to the same reference Using the MODE switch advance the altimeter under test to ALTITUDE mode Pump the vacuum to read about 25 000 feet on the REFERENCE altimeter Wait for readings to stabilize then adjust the OFFSET potentiometer until the altimeter under test and the STANDARD read the same Release the vacuum and wait for readings to stabilize Adjust GAIN potentiometer until the altimeter and STANDARD read the same
15. eir ovens powered at all times even when the instrument is not in use Unfortunately this is not practical using typical 12V aircraft battery power Once warm the Series 2000 consumes only about 1 watt Even at this low rate it would consume 50 of the capacity of a typical 20 to 25 amp hour aircraft battery in only 5 days MECHANICAL CONSIDERATIONS The instrument is ruggedly built and can withstand severe vibration but no device can be made totally vibration proof Mount the instrument securely This is particularly important for installations in aircraft powered by two stroke engines as is common with ultralights WARRANTY This instrument is warranted against defects in materials and workmanship for a period of two years from the date of purchase As such we will repair or replace at our option any unit found to be defective within this period You must file the warranty registration card with us when purchased preferred or show proof of purchase with a dated itemized receipt from a recognized aviation retailer Beyond the warranty period we repair and calibrate instruments promptly and for very reasonable cost CALIBRATION This section outlines the steps required to properly calibrate the Series 2000 altimeter Two different procedures BARO SET and FULL CALIBRATION are listed and vary considerably in complexity and equipment required The BARO SET procedure is comparable to pulling out the set knob on a standard mechanical alti
16. for 2 seconds After 2 seconds the LCD will go off indicating that the switch has been held long enough and when released the instrument enters the new mode Note that each mode can have several arrows leading into it but at most only two leading out 2S and momentary Also note what we refer to as the main loop This is the sequence PRESSURE ALTITUDE CLIMB and back again as was described earlier Each of the arrows involved in this loop has no label meaning a momentary press of the MODE switch Each of the modes on the main loop has some auxiliary modes that can be invoked by pressing the MODE switch for 2 seconds The auxiliary modes have been arranged so that they have some logical connection to the main loop mode from which they are accessed Take for instance the PRESSURE ALTITUDE mode A brief tutorial on the concepts of pressure and density altitude appears at the back of this manual Since pressure altitude is related to the barometric pressure reference it is linked to and accessed from the PRESSURE REF mode From the PRESSURE REF mode press and hold the MODE switch for 2 seconds When the LCD blanks release the switch and you will see the ats aes START PRESSURE ALERT ALTITUDE DELTA 25 2S PRESSURE 2S ALERT REFERENCE ALTITUDE MAIN LOOP 2s CLIMB RATE 28 2S 2S MODE BUTTON PRESSED DENSITY OAT FOR 2 SECONDS ALTITUDE Figure 1 MODE FLOW CHART PRESSURE ALTITUDE di
17. itial discrepancy between altitude and pressure are not an indication that it is out of calibration We just have to allow sufficient time for the difference to diminish to insignificance Assuming we initially set the barometric reference correctly typical warm up characteristics for the Series 2000 are as follows A couple of minutes after first powering it from a cold start displayed altitudes will typically indicate about 100 feet lower than true This initial difference will then gradually diminish over a period of about 30 minutes As aresult of this behavior the following operating procedure is suggested During normal runup set the altimeter to the known airport ELEVATION NOT the known BAROMETRIC PRESSURE This will then give the greatest displayed accuracy while leaving the pattern and potentially clearing local obstacles while climbing to intended altitude After 15 minutes or more the greatest accuracy in displayed altitude will then be obtained by setting the baro as reported by Air Traffic Control or an ATIS tape REMEMBER The MODE C altitudes reported by this instrument are not affected by the barometric reference setting and are always within the FAA designated specifications The above procedures only affect altitudes displayed on the LCD and are intended to explain and correct for an initial 100 offset Many electronic instruments utilize ovens to achieve high accuracy To avoid warm up delays some of them simply leave th
18. meter and adjusting so that the baro and altitude scales read correctly at a known fixed airport altitude This requires no special equipment other than radio access of the current local barometric pressure It is easily done by the end user without having to open the instrument The FULL CALIBRATION procedure is considerably more involved It requires specialized equipment and should only be done by qualified service personnel BARO SET 1 Allow the instrument to warm up for ONE HALF HOUR THIS IS EXTREMELY IMPORTANT A full and thorough warm up is required for proper adjustment 2 Obtain the current sea level barometric pressure from a reliable source ATC tower ATIS ASOS etc Note that ATIS tapes are typically updated at 45 minutes after the hour and diminish in accuracy as they age ASOS data where available is updated every minute and is always current as is the ATC tower 3 Set the instrument to the PRESSURE mode Using the UP DN switch set the reference to the current sea level barometric pressure 4 Set the instrument to the ALTITUDE mode Using a suitably sized straight blade screwdriver adjust the OFFSET potentiometer until the altimeter displays the known airport elevation The adjustment is accessible through the front panel left of the alert LEDs Wait one minute and readjust if necessary NOTE Be wary of airports that are not level Published airport elevations reflect the runway altitude at the control tower
19. numbered identical to connector pins but are not in order Figure 2 REAR VIEW POSITIVE 11 TO 35VDC RED PRESSURE PORT F PIN 26 BLACK CIRCUIT BOARD NEGATIVE g GROUND PIN 1 UNDER v PN 25 UNDER ee VOLUME CONTROL CONNECTOR 9000000000000 14V BACKLIGHT PWR e 000000000000 EON oooowoooo0oo00000 O E O O TERMINATION BOARD ay TYRAP STRAIN RELIEF Pins are grouped by functions 1 through 10 applies to all instruments and involves backlighting DC power serial data and audio outputs Pins 11 12 amp 13 are for the temperature sensor and function only if that a option is installed The remaining pins 14 through 26 all support the Mode C encoder option Table 1 lists the use of each connector pin and functional descriptions of each follows TABLE 1 CONNECTOR FUNCTIONS Pin Function Pin Function 1 28V backlighting 14 ground 2 14V backlighting 15 STROBE 3 GROUND 16 ENABLE 4 DC power 11 to 35V 17 C2 M 5 Not used 18 Cl O 6 Not used 19 B4 D 7 audio shield 20 B2 E 8 audio signal 21 Bil 9 serial data ground 22 A4 C 10 serial data 23 A2 11 temp probe shield 24 Al 12 temp probe red 25 C4 13 temp probe black 26 ground BACKLIGHTING Pin 1 or 2 is used for illumination of the LCD for night viewing 14VDC to pin 2 or 28VDC to pin 1 The wire supplied is pre wired to pin 2 since 14V is typic
20. or runway center If your altitude during this adjustment differs considerably from the airport reference your altimeter will be off by the same amount If a significant grade exists you should first relocate closer to and level with the tower FULL CALIBRATION This can be performed using either a pressure STANDARD displays pressure in inHg or mBar or a STANDARD altimeter displays altitude in feet Follow the procedure that applies to the STANDARD available The diagram on the following page shows the location of the various adjustments Using pressure STANDARD Equipment required a Pressure STANDARD capable of displaying absolute pressure in inHg and accurate to 0 02 inHg over a range of 8 0 to 31 0 inHg or comparable units if using mBar model b Hand operated vacuum pump if not built into pressure STANDARD c 14VDC power source capable of 400 mA 1 Shut off power and remove the interface circuit board connector from the back of the instrument At back of instrument disconnect static port plastic tubing 2 Using a 1 Philips screwdriver carefully remove the two screws from the front face Push on the circuit board extending from the back of the case then remove the electronics assembly 10 Connect tubing from STANDARD to pressure port on back of altimeter using plastic tubing and size adapters as required
21. pheric pressure of the air in which the aircraft is enveloped One might think that these are related only to altitude and es therefore knowing the altitude will tell the whole story but this is not the case At any given altitude pressure and density will vary from day to day and even hour to hour In order to get around this problem experts studied the atmosphere and developed what is called a standard day This is simply a tabulation of the AVERAGE pressure density and temperature versus altitude taken over many years of measurements Using this standard day we can refer to any air density or pressure indirectly in terms of an equivalent altitude For instance instead of saying that the current atmospheric pressure is 22 225 inches mercury we can say that the pressure is the same as that experienced at 8000 feet on a standard day Stated more simply we say that the PRESSURE ALTITUDE is 8000 feet In a like manner instead of saying that the current air density is 0 00167 slugs per cubic foot these are proper units we say that the density is the same as that experienced at 11 500 feet on a standard day In simpler words the DENSITY ALTITUDE is 11 500 feet Let s summarize it from a slightly different viewpoint Pressure altitude IS NOT AN ALTITUDE it s a pressure When we say that the pressure altitude is 5000 feet what we re really saying is that the pressure is the same as that normally experienced at 5000 feet on a standard day
22. re sensor is not properly connected this byte will contain 80h 128 C This highly improbable yet easily detectable value is used to indicate an off scale condition Under the same conditions the two density altitude bytes will contain 8000h 32 768 feet Climb rate is encoded in 16 bits with 1 LSB equal to 1 foot minute As with altitude displayed values are rounded but serial data is not ALTITUDE PRESSURE ALTITUDE DENSITY ALTITUDE OAT CLIMB RATE a cs a a m a m a a o on N N o o o o no 4 4 4 a a OV gt TIME 1111101111110010010011001000010011100010110010101011001010011100100111111110001100101011111111111111 BINARY F 3 2 3 8 c 4 3 5 3 9 3 E F c 4 F F HEX 8 DATA START BIT STOP BIT BITS A FIELD OF 9 DATA BYTES IS OUTPUT EVERY 600 MILLISECONDS THE BIT STREAM EXAMPLE SHOWN ABOVE DEPICTS ALTITUDE 323Fh 12 863 FEET PRESSURE ALTITUDE 34C8h 13 512 FEET DENSITY ALTITUDE 3935h 14 645 FEET OAT FEh 2 C AND CLIMB RATE FF4Ch 180 FT MIN Figure 3 Serial Output Data Format PRESSURE AND DENSITY ALTITUDE This section is intended to explain the concepts of pressure and density altitude for novices or those veteran flyers that need a clearer understanding than they currently have Many critical aircraft performance parameters are highly dependent on the density and atmos
23. splayed as indicated by that LCD legend and shown at left in the set of figures at the bottom of the page We could also have determined pressure altitude by first setting the PRESSURE reference to standard pressure 29 92 for the Model 2000 and 1013 for the Model 2001 then read the ALTITUDE The PRESSURE ALTITUDE mode does this automatically and doesn t require us to alter the current reference and possibly forget what it was Press the MODE switch to return to the PRESSURE REF mode The next modes to be discussed are Outside Air Temperature OAT and DENSITY ALTITUDE Since these both directly affect aircraft climb rate they are accessed from the CLIMB RATE mode These modes are an option and if not installed or if a functional temperature sensor is not properly connected the LCD will indicate off meaning that the readings are off scale From the CLIMB RATE mode press and hold the MODE switch for 2 seconds to enter the OAT mode The LCD will appear as in the center illustration Note that there is no LCD legend that uniquely identifies the OAT mode Rather it is implied by the lower case c to the right of the digits indicating that the temperature is in C There is no provision for readings in F Momentarily press the MODE switch and the mode will change to DENSITY ALTITUDE Also note by observing the flow chart that repeatedly pressing the MODE switch will toggle between DENSITY ALTITUDE and OAT To return to the CLIMB RATE mode press an
24. times negative numbers while ALERT ALTITUDE will have much larger positive numbers equal to your current altitude There could be some confusion if trying to use the ALERT modes at very low altitudes where the DELTA and ALTITUDE would be comparable If altitude approaches or exceeds the established WINDOW both audible and visual warnings are generated The audio output can not drive a loudspeaker directly but must be wired into the accessory input of an intercom system It incorporates a built in volume control to set the level Audio is incorporated into all instruments Its use is optional as the visual indicators provide complete information The visuals are by means of the green yellow and red ALERT LEDs If altitude is within 70 of the selected WINDOW the green LED remains on continuously and no audio warning is produced For instance if the selected WINDOW was the default 200 feet no warnings would be produced if within 140 feet of the TARGET Likewise if the WINDOW were set to 500 feet no warnings would be generated if within 350 feet of TARGET If you exceed 70 of the WINDOW the yellow LED flashes and if audio is connected a beeping warning tone is also heard A high pitched tone indicates you are above target while a low frequency means you are below The audio tone is silenced by momentarily pushing the MODE switch but the yellow LED will continue to flash The yellow LED will stop flashing once the altitude is returned to within 7
25. y The 200 in the display indicates that an allowable WINDOW of 200 feet around the TARGET altitude is in effect This is a default value and can be changed from within this mode in 50 increments using the UP DN switch As depicted in the flow chart the ALERT SET mode is accessed only upon first entering the ALERT modes Thus once you move on to the ALERT ALTITUDE mode the only way to change the WINDOW is to exit the ALERT modes and start again Once the desired WINDOW has been set momentarily press the MODE switch to enter the ALERT ALTITUDE mode The only readily apparent difference between this mode and the normal ALTITUDE mode is that one of the ALERT LEDs will be on Altitude is displayed just as in the normal ALTITUDE mode but it is also being constantly monitored and compared to the TARGET altitude and WINDOW Press the MODE switch again to enter the ALERT DELTA mode Here the deviation above or below the TARGET altitude is displayed rather than absolute altitude This format makes it very easy to maintain a fixed altitude by simply holding a zero reading Negative values indicate that you are below TARGET positive above Repeatedly pressing the MODE switch toggles back and forth between ALERT DELTA and ALERT ALTITUDE There is no difference in the LCD legends or LEDs and the only clue as to which mode you are actually in is the numeric values There is generally no confusion since the ALERT DELTA mode will usually have small and some
Download Pdf Manuals
Related Search