AS 12 - CT-142 and Emulated INS (INS 2) Flashcards
Review Questions
What are the problems which inhibit alignment at high altitudes?
Undetectable tilt (simulated by computer) preventing initiation of gyro compassing
Inability to accurately resolve true north
Review Questions
How long is the Schuler Period?
84.4 minutes
What are the two components for the Honeywell IRS?
Inertial Reference Unit (IRU)
Mode Selector Unit (MSU)
What components does the IRU contain?
Inertial sensor assembly
Microprocessors
Aircraft electronic interfaces
Power supplies
Where is the IRU located and housed?
Located under center floor of crew compartment
Housed on a rack that also serves as mechanical interface between IRU and aircraft.
What does the MSU provide?
Inertial mode selection, status indication and remote test initiation.
Where is the MSU located?
Go over this card with the presentation, im assuming i meant “MSU control panel”
Flight deck center console
What kind of system is the Honeywell IRS?
A strap-down, Schuler-tuned inertial reference system.
Accelerometers and ring laser gyros in the inertial sensor assembly measure what?
Accelerations and angular rates of the aircraft
What kind of power does the IRU receive? What are the associated voltages?
The IRU can receive AC or DC power and provides the switching to primary or secondary DC
The IRU can operate with either 115V AC or 28V DC voltages
Does the IRU require a cooling air supply? If so, how is this supplied?
Yes, it is supplied through the air conditioning system or the AC/DC blower kits.
If a loss of cool air to the IRU occurs, what must happen after a specified time?
Shutting down the IRU
What are the four basic inertial modes for the IRU?
Off
Align
Nav
Attitude
Describe the Align Mode for the IRU
The IRU aligns it’s reference axes to the local vertical and computes heading and latitude by measuring horizontal earth rate components
How long does the IRU take to align at the equator, between latitudes 60 & 70 and above 70 Deg?
60: 2.5 minutes
Between 60 and 70: Maximum of 10 mins
Over 70: More than 10 mins
In Nav Mode, the IRU supplies inertial position reference for the aircraft and provides outputs via the FMS:
Aircraft attitude Velocity vectors Body rates Body accelerations True heading Wind data Inertial attitude Lat and Long
(A Very Bored Boy That Waits In Line)
What does the IRS use as the starting point for positional computations?
The Lat/ Long entered during the align mode
The nav components calculate what in nav mode?
Present position
Velocity
Heading
Attitude
Attitude Mode, once rapid levelling has been completed, provides valid outputs of:
Body axis accelerations
Attitude rates and angles
Vertical velocities
Inertial attitude
(Bodies Are Vertically Inline)
What is not provided in Attitude Mode?
Navigation outputs
When should Attitude Mode be selected in the air?
When the MSU fault enunciator illuminates
After the IRS has temporarily lost all power
What are the Alignment requirements?
Operator must enter present position via the FMS
IRU conducts a reasonability test of new position: compares with previous position at last shutdown
How might the Alignment test fail?
If the new position is > 1° of the stored value
A correct Alignment test may fail if?
A new IRU has been installed; or
Aircraft was moved since its last shutdown
How can you overwrite an Alignment test?
Entering identical coordinates twice
At the end of the Alignment phase, what must pass the System Performance Test?
Latitude
Regarding the Systems Performance Test, the latitude entered must be within?
30 min of arc of the latitude computed by the IRS during alignment.
If an entered latitude passes the system performance test, alignment is complete and it allows entry to what mode?
Navigation mode
Information is fed from the IRU directly to the ATS. The ATS maintains a database of inertial information including:
True heading True track angle Present Lat and Long Inertial ground speed Wind velocity System status
(The True Problem Is Windy Seas)
How is IRU data given to the pilots and the navs?
IRU data to pilots through FMS
IRU data to navs through ATS via FMS
True of false
The aircraft IRU (INS) operates as any INS does?
True
On the emulated INS control panel, what three modes are there?
Manual - allows manual leg changes
Automatic - automatically sequences to the next waypoint capture
Remote - Allows system manipulation without affected system navigation to current waypoint
Nav and position info is sourced from what?
The IRU
How many waypoints can the INS hold?
Max of 20
Review Questions
What is the source of the inertial information used by the ATS?
The aircraft IRU
Review Questions
What does the “Alert” annunciator on the Waypoint Information frame indicate?
90 seconds to the next waypoint or 90 seconds abeam if off track
Review Questions
What does the Warning annunciator on the Position Area indicate?
A malfunction is preventing alignment of the IRU; or
A latitude that is inaccurate by more then 1/2 a degree is entered
Review Questions
What are the two main components of the IRS?
Inertial Reference System
Mode Selector Unit
Review Questions
What are the two main type of information provided by the INS?
Navigation and Attitude
