AFCS Flashcards
What five subsets comprises the AFCS?
The Automatic Flight Control Set (AFCS) (Figure 3) enhances the stability and handling qualities of the helicopter. It is comprised of five basic subsets: stabilator, SAS, Trim, FPS, and Flight Director (FD) sets. (WP0098)
The FLT DIR FAIL caution will appear when?
FLT DIR FAIL - Indicates that one or more flight director functions has been disengaged.
What component controls the airspeed hold mode in the UH-60M? Where does the inputs for airspeed hold originate?
Airspeed Hold (IAS): Maintains airspeed using inputs from the air data computers. Pressing the IAS button on either FD/DCP causes the AFCS to hold airspeed at the engage point. To change to a new airspeed, the cyclic stick TRIM beeper switch is used to move flight controls to change airspeed, and then the switch released when the helicopter has stabilized at the new airspeed. The airspeed reference can also be changed by adjusting the IAS PUSH-SYNC knob on either FD/DCP.
Which FCC receives a vertical accelerometer input?
FCC No.2 Only (Student Handout)
What puts the Stabilator in the Degraded Mode (Limited Auto)? Manual Mode? (Reference Student Handout)
No Loss of CLAP, nor MANAFCS = FULL AUTO MODE
The STAB DEGRADED advisory indication may appear on the EICAS display with both channels continuing to program the stabilator with limited or lost functionality. This may result from a lost or invalid sensor indication or sensor failure of the Collective Positions Transducer • Lateral Accelerometer • Actuator Stuck (Position Known) • Pitch Signal (EGI)
How does each FCC know the stabilator status of the other FCC?
By communication over the Cross Channel Data Link (CCDL), each FCC knows the other’s status. (Student Handout)
What are the two inputs that go into the FCC independent fault monitor for the Stabilator?
Airspeed and STABILATOR Position
When is the TEST function of the automatic mode fault detector feature disabled?
Weight off wheels condition or if Nr is greater than 10%. WP 0096.
If one or more of the FD functions have disengaged, the FLT DIR FAIL caution will appear
The FD COUPLE FAIL caution appears when a coupled FD automatically decouples due to a failure in the FD or related subsystems
What flight controls does TRIM control and where are the switches?
The cyclic stick four-way toggle controls fore/aft and lateral cyclic trim, while the collective stick four-way control moves the collective up/down or the controls tail rotor yaw using the left or right function. A TRIM REL button also temporarily releases trim on the collective and cyclic.
How do pilots engage the automatic pilot function of the flight path stabilization?
To engage the automatic pilot function, the pilot selects from the AFCS Panel:
AUTO CONTROL RESET.
SAS 1 or SAS 2 switches.
TRIM switch.
FPS switch.
SAS/BOOST switch.
Disengage the FPS by pressing the FPS switch to return to fully manual flight.
Stab will enter the STAB MANUAL MODE when:
Miscompare of ADC and STAB position
ADC signal loss
No “Hot Slew” signal
Actuator Failure (position unknown)
FCC failure
Cross Channel Data Link (CCDL) failure/signal loss
Synchro (Stab Position) failure/signal loss
What is the emergency procedure if you get a STAB UNLOCKED caution light in flight?
Land as Soon as Possible
Will the stabilator automatic mode function if there is an AC or DC power interruption?
No, it will revert to manual mode.
Which components interface with the stabilator system?
No. 1 and No. 2 EGIs
The flight control computers (FCC) process what inputs to derive stabilator actuator control signals?
The two FCCs receive airspeed, collective stick position, pitch rate, and lateral acceleration information to program the stabilator through the dual electric actuators. WP0098
