Temporary EICAS Advisory Message

[andrej]

Hello all,
having watched a following video:
https://youtu.be/cnjibudNwhs?si=nIyxo3rWMd9xcj-S&t=71

at 1m12s mark, the ENG 2 REVERSER (?) advisory EICAS messages appears for couple of seconds. This is during the start of the take-off roll, once engine thrust is (being) set.

What can cause such short message? Wiring issue, sensors not working 100%, or such "gremlins" occur more often on a real plane? 

Thanks!

[Hardy Heinlin]

Hello,

I don't know the cause of this reverser system fault, but I know that the message logic is supposed to remove the message above 80 kts, which happens in the video. So when the message disappears, the reverser system fault is still there, probably.


|-|ardy

[John H Watson]

I don't think people understand how many gremlins there are on these aircraft. This was highlighted by the Alaska Airlines accident. The pressurisation fault light could have been entirely coincidental with the door plug blowing out.

There are a number of reverser system position sensors that can really be given a shake during takeoff. The big worry used to be when two thrust reverser indications showed amber (transit), which could make the leading edges retract. That was fixed with a wiring update and more attention to sensor alignment procedures. This message can also be caused by a disagreement of air/ground relays, loss of DC power (indication and control) and relay glitches.

If they had noticed the message or the message latched a status message, of course, the engineers would have taken action.

The advisory message will display on the ground if there is a fault for more than 5 seconds and the airspeed is below 80kts.

[Jeroen Hoppenbrouwers]

I don't think people understand how many gremlins there are on these aircraft.

Don't start me on this. I just spent a week in Hong Kong basically on a 777 and next to the things I was there for, I saw so many things that "should not" be there/have happened that I develop a lot of respect for the engineers and technicians that keep whole fleets of these operational.

Including glitches, misunderstandings, and finger trouble with the increasingly complicated ground support systems and also increasingly the hard core IT-level security elements. And we all know, more security = more fragility = less robust = ... less safe? Ah well, let the discussion start.

Hoppie

[andrej]

Dear all,
thanks for your clarification. It makes all sense, but still it made me wonder.

If the message disappears at 80kts (as intended), when is it scheduled to reappear? On ground (after landing) or above 400' AGL? Or at a later stage?

The video shows that during the landing all engines reversers worked well (all four engines were in reverse). So most likely a temporary glitch.

Thanks!
Andrej

[Magoo]

So when the message disappears, the reverser system fault is still there, probably.
|-|ardy

Not sure I'd want to take that plane up in the air with this EICAS caution at such a low speed.
BA had the leading edge flaps retracting after take off due to a simillar false warnin in JNB years ago if I remember correctly, The pilot save the day with some extreme level of flying skills.

[John H Watson]

If the message disappears at 80kts (as intended), when is it scheduled to reappear? On ground (after landing) or above 400' AGL? Or at a later stage?

If the problem is still there, the same fault logic will be looked at. The Advisory msg should only be triggered if the problem is there for 5 seconds. It will only appear/reappear on the ground below 80kts. It should appear as a latched Status Message (without ground mode or 80kts).

I don't know if the flight crew would respond to Status messages. 

[andrej]

Thank you John! Very much appreciated.

[evaamo]

and also increasingly the hard core IT-level security elements. And we all know, more security = more fragility = less robust = ... less safe? Ah well, let the discussion start.

Hi Hoppie! Hope all is great in sunny Portugal!

I'm not an expert by any means in avionic security, but as a cybersecurity guy I am definitely interested in  the "more security = more fragility" argument. I won't say I disagree, but I'd definitely need to read your reply first. What I do know is: "more security = more complexity = more abstraction/opacity = less safe" in general terms (systems?). I even wrote a paper in that regard (it's in Spanish though). I do have friends that have worked in hacking avionics (ethically) and their findings are quite interesting. However, I'm not of the idea that there are hardcore or strong [cyber]security measures but mostly "network segmentation" stuff in place. Like I said, I'm not an avionics expert, so I'd love to know more. Here's a well-known publication by a respected security researcher, if you want to take a look:

https://i.blackhat.com/USA-19/Wednesday/us-19-Santamarta-Arm-IDA-And-Cross-Check-Reversing-The-787-Core-Network.pdf

Looking forward to your reply :-)

Best,
-E

[Magoo]

I don't know if the flight crew would respond to Status messages. 

No, crew do not respond to Status Message, but this was an EICAS caution...

[Jeroen Hoppenbrouwers]

What I means (I am in a hurry now) is that the more security you add, by definition the more of these gear boxes can break. For example a simple security certificate, which depends on a date range, the system clock, the CA chain, trust in a root CA, recent enough revokation list, ... and I recently found out that there are additional things nobody knows about that you can require such as whether a WiFi SSID is set to shown or hidden. If not hidden then fail. With everything else ok and no error message to not leak information. Two days lost. THAT is fragility.

Flight ops departments sort of hate it when they need to delay a flight because of a tiny hiccup in the security setup. They prefer stupid username/password over sophisticated security that is automagical until it just fails with no way to diagnose it.

Hoppie