Primary Flight 3 inch Digital Display
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Frequently Asked Questions
Please review the AV-30-E frequently asked questions prior to submitting a support ticket or placing a phone call.
Yes and no. During the majority of flight conditions, they are equivalent. However, during conditions where the aircraft is moving through a mass of air that has a vertical component, the behavior is slightly different.
As vertical updrafts are rarely of concern, the scenario to look at is the downdraft during final approach. In this environment, the aircraft will sink at a rate that is not consistent with the aircraft pitch. As the algorithm utilized compares the aircraft pitch to the actual flight path through the air, this will result in an artificial positive AoA (see diagram).
A downdraft that forces a sink rate of -1000 FPM will effectively increase the current AoA by approximately 5.6 degrees (this is speed dependent).
In effect, this makes the AoA thresholds more sensitive and an alert will be generated earlier than normal – but that’s a good thing in this scenario.
If a down-draft of this magnitude is experienced, the pilot action is to add power; Similarly, if AoA exceeds the configured limit, the pilot action is also to add power. As the pilot actions are identical for both scenarios, it can be argued that the source of unexpected altitude loss (downdraft or a wing losing lift) is irrelevant. Add power.
Interestingly, if taken to the extreme, the probeless AoA system actually starts to behave like a wind-shear alerter and any downdraft that is sufficient to cause excessive pitch vs flight path angle will generate an alert – it’s effectively a sink rate alert at that point.
In a probed system, as the probe is only measuring ambient air angle and loss of altitude is not measured, this arguably advantageous behavior is not available.
Angle of attack is determined by comparing aircraft pitch to the actual flight path angle through the air. This is equivalent to the angle at which the wing is intercepting the body of air surrounding the aircraft – exactly the same as a probe based AoA system. Pitch is determined by a precision internal AHRS, and flight path angle is determined by a precision ADC (airspeed and vertical speed). The resulting angle is then augmented with G-Load, as determined by internal acceleration sensors.
For example, during a climb, if the pitch angle is 10 degrees up, and the aircraft’s flight path through the air (forward airspeed and vertical speed) is also 10 degrees up, the equivalent AoA is 0 Degrees. However, if the flight path angle through the air is only 7 degrees, then the equivalent AoA is positive 3 degrees as the wing is no longer able to maintain full lift.
Therefore, no dedicated AoA probe is required – only internal inertial and pressure sensors (8 in total). Connection to the aircraft’s pitot static system is required.
Reference Sperry Patent #3,948,096 for additional implementation details.
We are asking for approval to utilize the AV-30 as a stand-alone attitude indicator, attitude indicator and directional gyro (dual unit installation), installation as a replacement for the turn coordinator (leaving the existing attitude indicator in place), and as the required backup in an EFIS installation.
If the installation configuration leaves no instruments that require a vacuum source, the vacuum pump system may be removed from the aircraft via a 337 field alteration process. The removal of the vacuum system is not included in the AV-30-C STC approval.
By default, the AV-30 is a non-slaved DG. The good news it that this reduces installation complexity dramatically (no GPS antennas required, no remote mount magnetometers, no field mapping, no calibration).
Power and ground are the only required connections when the unit is installed as a DG.
The bad news is that it operates the same as a non-slaved DG. On power up, a minor heading adjustment will be required. (last known heading is saved). During flight, it will require minor corrections.
When interfaced to a GPS Navigator, the DG can optionally operate in Track mode and no corrections will be required. For day-to-day-operations, GPS track mode is generally preferred over heading.
Occasionally when actual magnetic heading is required (ATC clearances in large cross-wind environments), the non-slaved DG is available, or simply use your wet compass for those operations.
The system hardware is architected to support a remote magnetometer in the future.
The AV-30 provides an RS-232 receive line for “aviation” or “moving map” output provided by virtually every panel mount GPS navigator in service. This data is broadcast by the GPS navigator and no data is sent from the AV-30 back to the GPS unit. NMEA is also supported, which is output by most hand-held GPS units.
When connected to an external GPS navigator or hand-held, AV-30 operates as a repeater display. The data provided includes current waypoint ID, distance to destination, ground speed, cross track error, desired track, and bearing to waypoint.
This data can be overlayed in the textual fields as desired and is used to create the compass rose (GPS Track), moving map display (ARC Mode), and create the GPS HSI presentation when the AV-30 is operating as a DG instrument. When operating as an attitude indicator, it can drive the direction tape and provides a bearing-to indicator.
The AV-30 does not currently support vertical navigation display, but this feature will be introduced with the APA-10 autopilot interface box.
We are currently collecting inputs on which aircraft to include in the initial AML, and will continue to grow the list after the initial STC. If you would like your aircraft to be considered, please let us know your make and model here.
No, the initial STC will not have autopilot capability.
Autopilot integration will be accomplished in a phased approach. The initial autopilot support will be for STEC systems (which have their own roll/pitch source) and allow the heading bug on the AV-30 to drive the heading datum input on the autopilot. This interface will be accomplished with the APA-MINI converter. Follow on autopilot integration will occur over time, with most likely the Century systems first. These interfaces provide roll and pitch, in addition to the heading datum, to the autopilot. This interface is accomplished with the APA-10 converter. The APA-10 converter also provides ARINC 429 interface capability, which allows full vertical and lateral deviations from a digital navigational radio to be displayed. The AV-30 display component is provisioned for these interfaces, but will require a software update with the applicable autopilot adapter becomes available.
The AV-30-C is undergoing certification via the AMOC AML-STC process. This is a new risk-based certification methodology that is being supported for Part 23 Class I and Class II Aircraft. We expect to complete this certification by the beginning of Q2 2020.