Master caution/System Annunciator logic Bug

[AngelOfAttack]

Hi, I noticed the overall logic issue with Master Caution(MC) and System Annunciator(SA).

Simply put, the MC and SA didn't stay illuminate with a condition in related system still presents but the "trigger" one already putted out.

Here is a easy sensorial to recreate this bug:

1. load in ready to take-off condition.

2.Turn OFF any one of the HYD PUMP, let's say, ELEC 2(A)

3.The MC and SA "HYD" illuminate with "LOW PRESSURE" light on ELEC2(A).

4.Reset MC, both MC and SA now extinguished, but LOW PRESSURE on ELEC2(A) still illuminatng

5.Turn OFF another HYD PUMP, let's say ELEC1(B)

6.The MC and SA "HYD" illuminate again, so far as expect.

7. Without Reset MC, turn on HYD PUMP ELEC1(B) again.

8.on IXEG 733, upon ELEC1(B) turn on and LOW PRESSURE light for ELEC1(B) it extinguished, the MC and SA"HYD" would also extinguished.

But IRL, since the ELEC2(A)'s LOW PRESSURE light are still illuminating on HYD panel, the MC and SA"HYD" would stay on, until been reset manually, or when all amber light on HYD panel off.

 

PS: this logic apply to all SA. likewise easy to test on ELEC.

PS2: This logic not cross different system, if I reset something on ELEC,but fault still these, a new fault on HYD not bring "ELEC" on SA, only "HYD"

[Litjan]

2 hours ago, AngelOfAttack said:

But IRL, since the ELEC2(A)'s LOW PRESSURE light are still illuminating on HYD panel, the MC and SA"HYD" would stay on, until been reset manually, or when all amber light on HYD panel off.

Hmm - I don´t know and can´t confirm it on the real aircraft anymore.

Currently our logic says "if you reset the master caution for a certain warning, the logic considers it acknowledged". It may be true what you say and the logic is considering warnings "system wide" and not only "single warning wide".

Thanks for your report, we will consider it when updating the 737.

Be aware that there is a special case for the center fuel pumps, they will only trigger the master caution if BOTH of them are putting out low pressure.

Thanks, Jan

 

[AngelOfAttack]

23 hours ago, Litjan said:

Hmm - I don´t know and can´t confirm it on the real aircraft anymore.

Currently our logic says "if you reset the master caution for a certain warning, the logic considers it acknowledged". It may be true what you say and the logic is considering warnings "system wide" and not only "single warning wide".

Thanks for your report, we will consider it when updating the 737.

Be aware that there is a special case for the center fuel pumps, they will only trigger the master caution if BOTH of them are putting out low pressure.

Thanks, Jan

 

I know this is not well documented, I can't find such detailed description on FCOM or AMM, But I observed it on 737NG and confirmed with some older instructors who had flown on -300 that this behaviour is same with NG. To be fair I also don't have real or simulator on Classic to fully confirm it for now.

[AngelOfAttack]

Still there with 1.5

[Litjan]

10 minutes ago, AngelOfAttack said:

Still there with 1.5

Yeah, we didn´t touch it...yet ;-)

 

[robbietp1]

On 1/19/2022 at 2:36 AM, AngelOfAttack said:

Hi, I noticed the overall logic issue with Master Caution(MC) and System Annunciator(SA).

Simply put, the MC and SA didn't stay illuminate with a condition in related system still presents but the "trigger" one already putted out.

Here is a easy sensorial to recreate this bug:

1. load in ready to take-off condition.

2.Turn OFF any one of the HYD PUMP, let's say, ELEC 2(A)

3.The MC and SA "HYD" illuminate with "LOW PRESSURE" light on ELEC2(A).

4.Reset MC, both MC and SA now extinguished, but LOW PRESSURE on ELEC2(A) still illuminatng

5.Turn OFF another HYD PUMP, let's say ELEC1(B)

6.The MC and SA "HYD" illuminate again, so far as expect.

7. Without Reset MC, turn on HYD PUMP ELEC1(B) again.

8.on IXEG 733, upon ELEC1(B) turn on and LOW PRESSURE light for ELEC1(B) it extinguished, the MC and SA"HYD" would also extinguished.

But IRL, since the ELEC2(A)'s LOW PRESSURE light are still illuminating on HYD panel, the MC and SA"HYD" would stay on, until been reset manually, or when all amber light on HYD panel off.

 

PS: this logic apply to all SA. likewise easy to test on ELEC.

PS2: This logic not cross different system, if I reset something on ELEC,but fault still these, a new fault on HYD not bring "ELEC" on SA, only "HYD"

I believe you are correct here, if you turn back on one pump but still have one with low pressure your MC light should still remain on as you have low pressure in the Hyd system. It should only extinguish itself when there is no low pressure light at all or when you press it to clear. if you turn off both pumps, it should come on, if you turn back on one pump it should stay on also.