MEMS AH1000 Test Knowledge Flashcards
How frequent does the body rate monitor test take raw data? Where is the raw data located and what is it called?
1 second worth of data. The data is located in the device SN directory. With the file name called “filtered_ARINC_ATP_RCD_DATE_TIME”
What files does the ETS group looks at when troubleshooting test equipment?
The results files in the device SN directory
What is room ATP? What are some characteristics of the test?
Also known as quick ATP
- Just a functional test (should operate this way and does not need calibration)
- no rotation tests
-used for troubleshooting
-test operates at different voltages
- can be ran on HASS and rate table
What can the ATP also be named as?
Performance test
Why is integration ran before CAL?
Running integration means there are no cal coefficients, so calibration has to be run
Why does the “NVM_Aircraft_install_data_update” appear in the fault log? Do we count this as failure when we do ATP in house?
-When a device is installed in a new airplane or tester (which has APMs)
-We count this as failure if we do an ATP
What other RG event log faults do we ignore and why?
Faults that say “IGNORED”
Magnetometer faults
-The magnetometer is not our issue since Olathe makes them
Heading mode faults
-Field strength is low in areas
What is the easiest way to find the order of power cycles in the RG Dump?
-There is an upper limit in power cycles
-Higher faults are the latest faults and lower faults are the older faults
What is different between the HG2205AB02 and HG2205AB03 tests at integration?
Gyro config file is different between an HG2205AB02 and HG2205AB03
-Filtering values
-They loaded at integration test
What is the No Accel Bias transient test parameter at integration?
It is the expected the accel bias transient to change to a certain degree in 20 minutes
What are two charts to look at after calibration is finished?
The rate bias poly chart and rate bias look up table
How do I access the calibration charts?
You can’t access the charts but you can access the raw data to plot the charts.
- Go to the engineering tab on the device directory
- Go to the cal_eval_tool folder and copy sn_56xxxx_avg_coeff.xlsx (2018 version)
- Go back to the device serial no. directory and open the latest calibration folder
- Paste into latest cal folder
- Click on the latest avg coeff file (SN_56XXX_Date_Time_AVG_COEFF.txt)
- Copy all the values
- Access the pasted excel file in the cal folder and paste the values in the “Coeff Entry” tab
- Click on the “RateBiasPolyChart” to access the rate bias raw polynomial fit chart
- Click on “RateBiasLUTChart” to access the Rate Bias Look-Up- Table
What does Tim refer to as Swapped axis?
Need more clarifcation on this but the test equipment writes the APM
How did Tim describe the x and y gyro performance at calibration?
-There are in the x and y accel axis (should be seeing 0 G)
-Box real time bias estimator uses those accels
-Cal failures that usually point their coefficients being the biggest
Why is ATP in the UG8000 (8 hrs) longer than the UG7000 (5 hrs)?
The UG7000 has 2 slots while the UG8000 has 4 slots
What is the last test in ATP before the temperature completely changes
?
Drift test
What is the first test after the temperature completely dwells?
ARINC Power Up BITE Test
What is AGC?
Automatic gain control (AGC) is a technique used in communication systems to maintain a consistent signal strength level in dynamic real-world conditions.
When is the ATP Thermal Record test done?
The ATP Thermal Record Test is done during the ramping period from cold to hot
What is the AGC in gyro cca terms?
Health check (range of how much push the control loop should push)
What are examples of symptoms of bad date code ASICs in ?
RG Dump showing GYRO_AGC_2_RANGE_FAILED faults
ATP Thermal Record Test Failures
Even marginal failures in rotation tests
What was the period of devices that were shipped with gyros installed that had bad ASIC date codes? What was the percentage of devices that were found with them after the investigation in shop?
May of 2019 to August of 2021. 6 percent of the devices sent out were found bad
What were one of the physical symptoms found of a gyro that had bad ASICs?
One row of vias seem like it had a plating problem when it was created. Cracks were seen in the vias
What is done with the event log before testing?
We clear the event log before testing
How long is the drift test in ATP? How often is it performed in ATP?
This test requires approximately 20 minutes to perform. It is performed three times during the ATP, once at each temperature, requiring a total of one hour of test time
What is the purpose of the drift test?
The primary purpose of this test is to measure Mag Heading output drift due to residual Z axis gyro bias.
What is the pitch and roll angle output system level requirement at the attitude accuracy drift test?
The Attitude Accuracy Drift Test also verifies Pitch and Roll angle outputs stay within the +/- 0.5 deg system level requirement.
What is quick summary of how the attitude accuracy drift test starts?
1 AHRU is powered off.
- The rotation table is positioned to 0° inner axis, 0° degrees out axis.
- The AHRU is powered on with normal inputs provided. Magnetometer inputs are included in these.
- The AHRU completes alignment and is allowed to operate in Magnetic Heading mode for 3.8 minutes.
- The AHRU is commanded to DG mode. This stops the real time bias estimator. An initial Mag HDG value is read.
- Every 30 seconds for the next 10 minutes the Mag HDG is read and a delta to the initial value is calculated. This delta is tested against limits based on the 10 or 20 deg/hour requirement.
What happens when the device is in magnetic heading mode?
During this time the AHRU’s real time bias estimator is running, and a real time bias compensation is being calculated.
How does the AHRU compensate the magnetic heading output even when magnetic heading mode is off?
The AHRU will continue to use the last real time bias estimate to compensate the Magnetic Heading output.
How long after power up does the AHRU estimates biases for each of the gyros (sensors)?
30 seconds
At what temperatures is the Power Variation test done for New Build AH1000s (HASS and ATP)?
Hot and Cold temps during HASS
Room temp during ATP
What is AH1000 ATP Testing Approach?
AH-1000 ATP incorporates a “Testing Functions” approach
- Isolate and test functions one at a time.
- Easily map each ATP test to a Sub-assembly
At what temperatures is the Power Variation test done for RG AH1000s (HASS and ATP)?
Test performed at cold, hot and room temperature during ATP
What is the PS tests for DC-to-DC converter?
Typical test technique to change external power from the station or input power on the UUT. When this is done, the tests make sure the UUT power rail voltage levels stay in spec and internal does not reset.
