AFCS Malfunctions

Question 1

You see AP A.TRIM, what does this mean in simple terms?

Answer 1

The aircraft AP cannot hold an attitude anymore

Question 2

You see in the upper portion of the PFD a P, R or Y, what do these letters mean?

Answer 2

They are associated with an axis which has lost partial (single actuation) or complete (total actuation) control by the AFCS

Question 3

You have had a trim runaway, what are your actions?

Answer 3

Press the AP SAS cut button on the cyclic, this will get the aircraft to a known state, re engage the different axis until the failed one is obvious at this point RTB and land - practical

Question 4

You are flying along and see AP A.TRIM, AUTOPILOT and respective P/R/Y indications in the PFD, what are your CANCA actions?

Answer 4

C - “AP TRIM, AUTOPILOT”
A - Hands on flight controls, safe height, HDG and speed
N - My intentions are to terminate the sortie and land via a normal circuit pattern”
C - NFP can you make a PAN call to inform TWR of our intentions
A - Checklist actions, pre landing checks, PWP

Question 5

You see “ACTUATION” on the CAD and “P” in the PFD, what does this mean to you?

Answer 5

This means that one of the two control actuators used in each axis has failed, in this case the pitch axis. The system is still fully functional but can be considered degraded

Note: if both systems fail AP TRIM will appear accompanied by the “TRIM”caution on the CAD, the P/R/Y in the PFD will also be red

Question 6

How do you tell the difference between a single and double actuation failure?

Answer 6

Single: only “ACTUATION” will appear in the CAD, P/R/Y in the PFD are amber
Double: AP TRIM will appear, ACTUATION in the CAD, P/R/Y in PFD are red

Question 7

In a TRIM RUNAWAY, how do you figure out which axis has failed?

Question 8

What does “AUTOPILOT” caution mean in terms of the system?

Answer 8

The autopilot and associated upper modes have failed however all SAS systems are still working and the aircraft should be treated normally

Land - Practical

Question 9

What is the difference between AHRS 1 and 2?

Answer 9

AHRS has P&R SAS so if it fails P/R SAS will fail, otherwise they are the same

Question 10

Explain the difference between AHRS failure first and second time occurring

Answer 10

1st time: GYRO + AHRSi + <—> Att
2nd time: AP TRIM + Gyro + AHRSi

If you see “GYRO” and AP TRIM dos not light up, BF is hands on and RCU reconfigure to the unfailing side (The one with “<—> ATT”)