Sandel ST3400 Class A TAWS

Posted Monday, July 01 2013 as Company News

Troubleshooting in the Maintenance Mode

From Sandel Product Support,

Charlie here, talking about how to troubleshoot the ST3400A on the ground using the maintenance mode. For the airdata portion the use of a Pitot/Static Test set will be needed for proper results.

First we need validate the inputs to the ST3400A. To do this, we will need to access the Maintenance mode doing the following:

1.    With power off to the ST3400A. Hold the BRG1 & BRG2 soft keys, and then turn on power. Continue to hold until you see the Index page then release. At that time press the “RMI” key to place the ST3400A in “EDIT” mode noted at the top right of the screen. VTE data is as follows: VTE: 010 waiting on data, VTE: 100 Valid data and VTE: 300 data is timed out and not useable.

2.    First we will check the Airdata input pages 3 & 4.

     a.     Assuming that you have an airdata LRU connected to the ST3400 for Airdata Page 1 we will start with the CBA1 (Corrected Baro Altitude). With the cursor pointed to CBA1 you should see at the top of the screen by “VALUE” the Baro Alt readout. This should read what the Pilot’s Altimeter readout is and also while varying the Baro Knob it should track the altimeter reading. The VTE will be 100.  Set the Pitot/Static Test Set so that you can check Baro/Pressure Altitudes up to the aircraft ceiling.

     b.    Next, Press the “TOPO” key and then press the “UP” arrow on the right side of the indicator to change the Baro label from #204 to #203. The indication at the top of the screen should read “Pres Alt”, adjust the Pilot’s Altimeter to 2992. The readout should match. The VTE: will be 100.  Next, press the “TOPO” key to move the cursor back down to the “CBA1” field.

     c.     Move the cursor down to the “BR1” field so that we can check the Baro Rate or Vertical Speed. The VTE will be 100. Set the Pitot/Static Test Set to a vertical rate of 500 ft per min and verify the results at the top of the screen beside of “VALUE”. Set to 1,000 ft per min and verify results indicated at top of screen.

Next use 2000 ft per min and verify results, then at 3000 ft per min.

     d.    Move the cursor down to “TA1” so that we can verify that the True airspeed is functioning correctly. The VTE will be 100. With the test set vary the airspeed from 50 to 350 knots to verify the results at the top of the screen. Once this is done you can return the test set to static altitude.

     e.     The last thing we need to check is the OAT function. Move the cursor down to OAT and verify at the top of the screen either OAT or IAT is indicating correctly. The VTE is 100. To see one or the other you will need to press the “TOPO” key to switch between them. Verify the results.

     f.        To check Airdata 2 page if configured repeat the above steps starting with step 2.

13.    Checking Heading and ADF information on page 5: ADF/HDG.

     a.     For any ADF set up 1 & 2, verify that if you use XYZ that you have a valid 26 VAC on the page: 15 Power. If you have an ADF coming in on P1 connector you must have 26 VAC excitation coming in on P1-16. If you have an ADF coming in on P2 then make sure you have 26 VAC coming into P2-16.

     b.    Verify that with a valid ADF tuned in that you are indication the correct direction at the top of the screen. If you are 180 degrees out of phase then select –XYZ or –S/C DC.

     c.     ADF Valid is selectable. If you have one for your ADF then make sure you wire it to the ST3400. If not set to “NONE”.

     d.    For heading information HDG1 & HDG2, with the cursor by HDG1 verify at the top of the screen that the Heading Value match’s with the Pilot’s or Copilot’s HSI. If they have HDG2 set, then verify also with the Pilot’s or Copilots HSI.

     e.     The Heading Valid is optional but recommended. If you have the valid set, then with your cursor by the HDG1 Valid, then look at the value at the top of the screen. It should say “Valid Data”.

     f.       Verify HDG2 if configured for Heading information also.

     g.     Verify that the VTE is 100 for all of the above tests.

14.    Programming Discretes information on page 6:

     a.     AP (autopilot) if selected. With cursor by AP, verify at the  top of the screen that when the autopilot is engaged the value changes to “ENGAGED”. “DISENGAGED” when autopilot is deselected.

     b.    Alert is used for optional switches and annunciations. There are two settings for this. The first inhibit Low will select P3-13 only. The second selection of Inhibit Low will give you the P3-13 and P2-09/24. You can check the logic for each remote switch that corresponds to the pins.

     c.     Test is used for optional remote Test switch. When you put the cursor by it watch the value at the top of the screen change when you press the remote Test switch.

     d.    Flaps is used in conjunction with the radar altimeter. Select the flap setting that works for your aircraft. With the cursor by flaps, run the flaps down and make sure that once they start moving the indication at the top of the screen is “FLPS  DOWN” and stays that way at any position that the flaps are in with the exception of all the way up and stowed.

     e.     Gear is used to tell us what configuration the gear is in. If it is a fixed gear aircraft then it must be set to Gear Down Low and hard wired to ground on P2-14. For normal operation of the Gear setting for Gear Down or up, you will need to verify operation either on the ground on jacks or in the air in maintenance mode on the ST3400.

     f.      Wipr (windshield wiper) when interfaced to the windshield wiper will increase the audio callout volume when selected. If it is interfaced, with the cursor by Wipr then look at the value at the top of the screen. It should say “Audio increase off” when the wipers are off. When the wipers are on it should say “Audio increase on”.

5.    Nav/ILSpage 7 check out.

     a.     Depending on whether your Nav is interfaced by 429 or composite, you will need to verify operation for VOR/LOC/G/S.

     b.    Nav1 set to Composite. Verify with a VOR generator that the VOR is calibrated. If not use the “CAL” under the COMP setting to adjust.

     c.     Next, you want to push the “TOPO” key while the cursor is by the “COMP” selection. Press the “UP” arrow button so that the value goes to “LOC DEV”. Verify with a generator that when you select “left” and “right” that the value changes correctly. Once done press the “TOPO” key to move the cursor back down.

     d.    Move the cursor to GS1 to check the glide slope information. Set the generator to down and verify that the value indicated Down. Next go up with the generator and verify that the value goes Up.

     e.     Verify for Nav2 and GS2 proper operation using the above steps to check proper operation of Nav 2 input.

     f.      For ARINC 429 inputs verify VOR/LOC operation as well as glideslope functions.

     g.     Bckcrs (back course) is checked by moving the cursor down to Bckcrs and note at the top of the screen that it indicates BC inactive when the Pilot’s HSI pointer in at the top of the screen. Verify that when the course needle is positioned to the bottom of the HSI that it indicates “BC ACTIVE”.

     h.    Verify that the VTE is 100 for all the above test.

6.    Radar Altimeter checkout page 8: RADALT.

     a.     RA1 is selected for your type of radar altimeter. And the VTE is100.

     b.    Valid must be connected to the flag circuit of the radar altimeter. This will go invalid depending on the system at 2000 or 2500 ft.

     c.     CAL. Making sure that you do not have any metal under the aircraft that would offset the radar altimeter readout. Adjust the cal to indicate “0” feet at the top of the screen.

     d.    D HGT is set for decision height announcement. With your cursor by D HGT and move the master radar altimeter DH set to 10 feet. Press the test button on the radar indicator and monitor the DH on the ST3400. As the test signal moves the needle to 50 ft or 100 ft then starts back down to zero feet thru the DH selection, you should see “Decision Height” appear at the top of the screen.

     7.    GPS/FMS Selection 1 & 2 checkout for Page 9 & 10.

     a.     With your current selection we will determine if you are having any problem with the GPS interface. We will use a Garmin 4xx for this example.

     b.    When you view the value at the top of the screen you want to verify with the aircraft outside or using a GPS repeater that the LAT/LON is valid. Verify that the data VTE is at 100. Press the “TOPO” softkey to change the label 310 LAT to label 311 LON and verify VTE 100.

     c.     If using the RS232 out of the Garmin for Altitude then check label 076 ALT for correct altitude readout and a VTE of 100.

     d.    If you are using a Freeflight 1201 RS232 then you will need to check the following:

     e.     LAT label 310, LON label 311, HAE label 370, VFOM label 136 and HFOM label 247 and verify that the VTE is 100.

8.    TCAS setup and check out.

     a.     Select on page 11: TCAS your type of TCAS if interfaced to the ST3400. Make sure you have a Valid TCAS KEY

in the key window.

     b.    Put the TCAS in TEST mode and verify that the information at the top of the screen goes Valid with a VTE of 100.

9.    Page 15: POWER.

     a.     Verify that if you are using either one inverter or both that they indicate the correct frequency and voltage for P1-16 and P2-16.

     b.    Verify that all voltages at the bottom of the screen are Green.

     c.     Verify that the Fan is running around 6500 to 6700 RPMs.

10.     Page 16 CRC.

     a.     Press the RMI softkey and make sure all values PASS. If not then the unit will have to come back to Sandel for repair.

This concludes the testing of the ST3400. I hope this helps in the field. If at this point you are still having problems contact Sandel product support for additional guidance.