PHI GOM S-92 - AFCS

Question 0

What provides signals for SSAS?

Answer 0

AHRS (Attitude Heading Reference System)

Question 1

Rate Gyros provide signals for the _____.

How many rate gyros are there?

Answer 1

PSAS
6

There are two rate gyros for each PSAS axis ( pitch, roll, and yaw). The No. 1 rate gyros supply rate signals for PSAS 1 , and the No. 2 rate gyros supply the rate signals for PSAS 2 .

Question 2

What is the difference between the SSAS and PSAS computers?

Answer 2

Computer functions are identical.

The only difference is attitude and acceleration input.

AHRS for SSAS
Rate Gyros for PSAS

Question 3

What limitation(s) are associated with SSAS?

Answer 3

Airspeed 120 KIAS
Takeoff in SSAS prohibited.

since secondary SSAS and the autopilot both have the same attitude input there is no error crosscheck like PSAS to AP. MTM

Question 4

What does SAS provide?

Is it inner loop or outer loop?

Answer 4

SAS provides short-term rate damping.

Inner loop.

Question 5

What is the function of the Rotary Variable Differential Transiometers (RVDT’s) in the AFCS system?

Answer 5

Give flight control position information to the AFCS system. One is on each control rod near trim actuators.

Bonus: Additional RVDT’s are in the throttle quadrant and collectives to send inputs to the FADECs.

Question 6

The ___________ and ______provide signal input for Enhancements in the AFCS System.
What are the enhancements?

Answer 6

accelerometers for:
Hover Augmentation
Gust Alleviation

AHRS:
Heading Hold
Turn Coordination

There are six accelerometers: a pair of lateral , a pair of longitudinal, and a pair of vertical.

Question 7

If both AP computers are turned off, will enhancements and trim beepers still be functional.

Answer 7

No.

At least one AP must be engaged for trim beepers and enhancements to be operational.

With the AP switches off, the corresponding SAS function (via PSAS computer) still provides its rate damping stablization but the enhancement functions (via AP computers) are removed from that SAS actuator.

Question 8

What provides attitude inputs for the AP computers?

Answer 8

AHRS (Attitude Heading Reference System)

Question 9

If AHRS #1 fails, what indications will be seen in the cockpit?

Answer 9

Loss of Attitude Indicator, HSI, and IVSI.

AP #1 FAIL

Question 10

Why should the pilot turn off a failed autopilot?

Answer 10

To prevent any erroneous signals being sent to the flight controls resulting in an un-commanded movement or hardover.

Question 11

What is the trim rate of the trim system in ATT mode?

Answer 11

10% per second

Question 12

What maximum angle of bank is used by the Autopilots when coupled to the FD? What about decoupled using the cyclic trim switch?

Answer 12

23 degrees- flight director

30 degrees- cyclic trim
use the max trim limit for steep turns during your 297 ride

Question 13

What FD mode(s) may be coupled below 50 KIAS (Vmini)?

Answer 13

RALT and RIG approach

Question 14

What is the default climb or descent rate when utilizing ALTP to initiate a climb or descent?

Answer 14

500 FPM

Question 15

Why would a pilot select the VAP FD mode when flying a VOR approach rather than NAV?

Answer 15

VAP changes the sensitivity to provide more accuracy in tracking.

Question 16

How many different ways may a pilot de-couple or disengage the FD?

Answer 16

3 - SBY push button on the MSP,
FD disengage button on the cyclic, or
the COUPLE push button on the AFCS panel.

Question 17

What must be functional in the AFCS system to allow coupled flight?

Answer 17

Must be in ATT mode .

In order to have ATT mode available:
(2:1 rule or “rule of 3”)

1 PSAS with both AP
with cyclic and yaw trim
or
Both PSAS with 1 AP
with cyclic and yaw trim

For ALT hold: Collective trim is also required.

Question 18

What is the maximum rate of climb that may be commanded by flight director

Answer 18

2100 fpm

Question 19

Are both AHRS information sent to both AP?

Answer 19

Yes,

The AHRS outputs are averaged and sent to both AP.

Same with the ADC.

Question 20

In the event the AFCS can’t determine which AHRS is going bad what will it do?

Answer 20

The AFCS will turn off ATT mode and turn on SAS mode.

You may recover the ATT mode by determining which AHRS is bad and deselecting the associated AP. Then reselect ATT mode.

The AFCS will not accept AHRS reversion while in dual AP mode.
MTM

Question 21

The DCL function brings the airspeed down to _____knots at the runway and ___ft RADALT.

Answer 21

60 knots
50 feet

At the bottom of the glideslope, the auto level function captures the radar altitude at 50 AGL even though there is no RALT mode on the MSP selected.

Question 22

What does ATT mode provide?

with FD decoupled

Answer 22

Attitude hold for pitch, roll and yaw.

Heading hold/turn coordination.

(you can see when these are operating on the health page)

Collective trim beep is simply a position control without the FD coupled to Altitude.

Question 23

Can you hand fly an ILS using only the collective?

Answer 23

Yes

The collective “heading trim switch” sets half standard rate coordinated turn, so anticipate turns. The collective trim release allows descent on the glide slope.