ENG FAIL -- Inhibited on Ground?

[emerydc8]

I was paging through my manuals (and some other airlines' manuals) and noticed that under the Engines, APU EICAS chapter it states:

MESSAGE                  - Level      - Aural        - Message Logic

ENG 1, 2, 3, 4 FAIL  - Caution   - Beeper     - Engine failure or flameout. Inhibited on the ground.

When I activate a flamout on the ground in PSX, I am getting the ENG FAIL EICAS, master caution lights, and beeper. To me, this seems to be correct because I think I recall seeing this on low-speed aborts below 80 knots in the sim, but this is not what I am normally looking for to make that decision anyway (asymmetric thrust and N1 tape out of my periferal vision are more the tip-off).

Any comments on why these manuals would say that these indications are inhibited on the ground, or am I just misreading it? Thanks.

Jon D.

[John H Watson]

My manuals also say "air mode".

N2 less than 50%
Oil pressure less than 10psi (GE only,* 25psi for RB211s)
Fuel control switch ON
GCB is open
Airplane in air mode

Perhaps the momentary loss of a generator put some part of the air-ground system into air mode? (although I can't imagine a sim simulating this)

Can you recall which engine failed?

I find the oil pressure logic strange. I thought a windmilling engine in flight would be able to keep some kind of oil pressure in the system (EDIT)* Another manual specifies a more sensible 70psi for the GE. (EDIT #2: 10psi to 30psi is the acceptable range for oil pressure at idle, so it follows that sub idle/windmilling speeds will produce less than this)

Rgds
JHW

[emerydc8]

Hi John,

It was any engine I selected in PSX. I am using the GE engines.

I have to admit that I could have misunderstood this ENG FAIL EICAS all along. I thought I would get the master caution lights along with the beeper and ENG FAIL EICAS if it failed on takeoff, prior to when the inhibit kicks in at 80 knots.

In the sim, this is what they like to do to see if you are going to keep it on the runway using asymmetric brake and tiller which, under the circumstances, is the only way to keep it on the runway:

You are really light, there is low visibility (500RVR), a wet runway, and they tell you to use max thrust. They also throw in a 15-knot crosswind coming from the side of the outboard engine that they plan to fail on you at around 50 knots. At that point, the last thing you have time to do is look at the EICAS messages or caution lights. So, I can't remember if I get a master caution with ENG FAIL in this scenario or not. I am just happy that I kept it on the runway and I get to keep my job.

I am getting it consistently with PSX when I fail it on the ground, prior to takeoff. Maybe I'm misreading the manual and they mean that it is inhibited on the ground after 80 knots?

[ADDENDUM]:

From the PSX manual p.531:

Takeoff phase caution inhibit
The takeoff phase caution inhibit deactivates the beeper and the master
caution lights.
The takeoff phase caution inhibit begins when these two conditions are true:
+ Radio altimeters L & R are inoperative or RA is below 400 ft
+ ADC computed IAS is valid and rises through 80 kt
The takeoff phase caution inhibit ends when any of these conditions is true:
• 20 seconds have passed since the IRS pitch attitude rotated through 5°
• Radio altimeter L or R is operative and RA is above 400 ft
• ADC computed IAS is valid and below 75 kt
• ADC computed IAS is invalid
The beeper will sound and the caution lights will illuminate when the takeoff
phase caution inhibit ends while a caution message already exists.

So, the PSX manual seems to be consistent with the PSX sim (and with how I understood it would work in the airplane). The master caution and beeper are inhibited for an ENG FAIL on takeoff if it happens after 80 knots, and then it will un-inhibit at 75 knots on the abort. I just can't figure out why two different airline manuals appear to say that the ENG FAIL master caution lights and beeper are totally inhibited on the ground.

[Hardy Heinlin]

Hi,

the condition "airplane in air mode" is not included in PSX's "ENG FAIL" message logic.

Just the common take-off inhibit logic inhibits it in PSX.

Are the official manuals again simplified when they say "airplane in air mode"?


Cheers,

|-|ardy

[emerydc8]

Could John's quote be referring to the conditions required to automatically activate the ignition for a flameout?

[Hardy Heinlin]

Also, it's unclear whether the message is an event message or a continuous message.

An event message ("ALTITUDE ALERT", for instance) can be erased by pushing the master caution reset switch.

If "ENG FAIL" is an event message, and inhibited on the ground in the event of an engine failure, the message will not appear after lift-off.

If "ENG FAIL" is a continuous message, and inhibited on the ground, the message will disappear after touch-down during an E/O landing, and re-appear after lift-off.

In PSX it's an event message.


|-|ardy

[emerydc8]

In PSX, if you set up a flameout to occur at 60 knots on takeoff, you will get the two master caution lights, the beeper and the ENG FAIL EICAS. If you set it up to flameout at 100 knots, the two master caution lights and the beeper will be inhibited (you still get the ENG FAIL EICAS) until you decelerate through 75 knots on the reject, then you will get the master caution and the beeper. This is working as I had thought it would. The only question I had was why the manuals say that the ENG FAIL is inhibited on the ground.

[John H Watson]

Could John's quote be referring to the conditions required to automatically activate the ignition for a flameout?

No, there is a section in my manuals specifically for EICAS messages relating to engines. The logic is specified for that particular message.



Manuals also state that the relight is so good (particularly) on the RB211, that the engine will usually relight before the ENG (X) FAIL message appears.

[emerydc8]

Interesting. This would seem to contradict what I am seeing with PSX. I am getting the master caution lights, beeper and EICAS ENG FAIL on takeoff, when below 80 knots with either a flameout or severe FOD damage. I wish Boeing could have been a bit clearer on this.

[Avi]

I wonder what the logic is behind this on ground inhibition.
Why the pilots shouldn't get this warning (caution message)? In case of an engine failure the FP will definitely feel the asymmetric thrust and the NFP (or MP) should notice in the EICAS an engine failure (falling N1 or EPR). So what is the problem to get this message (as confirmation for a problem) below 80 kts when it is safe and preferable to abort anyway?

[Hardy Heinlin]

Manuals also state that the relight is so good (particularly) on the RB211, that the engine will usually relight before the ENG (X) FAIL message appears.

Interesting. This would seem to contradit what I am seeing with PSX. I am getting the master caution lights, beeper and EICAS ENG FAIL on takeoff, when below 80 knots with either a flameout or severe FOD damage.

Now, let's not get grotesque :-) A flameout set on the Instructor's malfunction menu is a flameout that the RB211 simply cannot relight immediately. Period :-) If we now move all engine malfunctions into the no-problem category we don't need no training sim anymore. Flameouts may occur in PSX also in adverse weather, without any malfunctions programmed on the Instructor, and those flameouts may relight the RB211 promptly :-)

And a severe FOD (foreign object damage) cannot be relighted at all because the N2/N3 shaft will stop completely.

My only question is whether the message inhibit just hides the message while on the ground, or never lets it get onto the message list if the failure occured on the ground.


Cheers,

|-|ardy

[emerydc8]

From what I was taught, PSX has it correct -- after 80 knots, an engine fail (whether it be a flameout or severe FOD) will result in an ENG FAIL EICAS, but you won't get the master caution lights or the beeper. They are inhibited until 400' or decelerating below 75 knots on an abort. My original post was just to ask why the Boeing manuals make the statement, "Engine failure or flameout. Inhibited on the ground." Maybe Peter knows.

[ADDENDUM]:

Okay, now I'm doubting myself. I found this in the latest Atlas Air check airman training guide:

Engine malfunctions general

 The ENG ___ FAIL EICAS caution message is inhibited on the ground so as not to distract the flight crew when an engine fails.
 Severe engine damage is assumed if any of the following:
 An engine failure occurs in association with high EGT.
 N1 and/or N2 are very low or at zero RPMs. This is why it is recommended that the ENG status page is reviewed after an engine failure (engine status called by PF). N2 can only be displayed on the ENG status page.
 Airframe vibrations occur in conjunction with abnormal engine indications.
. . . .

 Caution alerts will be displayed at the top of multiple messages below any warning alerts. The master CAUTION light illuminates for EICAS caution messages. Caution alerts are normally major system failures such as EQUIP COOLING or ELEC AC BUS x. The caution alert ENG x FAIL is inhibited on the ground.

[John H Watson]

Manuals also state that the relight is so good (particularly) on the RB211, that the engine will usually relight before the ENG (X) FAIL message appears.

For this fault message, the Fault Isolation Manual lists various procedures based on whether the engine relights or not. There may be water in the fuel, engine blade damage, fuel leaks, etc...

[Hardy Heinlin]

I think the manuals are clear enough now: The message is inhibited on the ground.

But some details are still unknown; imagine you do some touch-and-go circuits:

Which statement is true?

1. When an engine fails in the air, the message disappears after touchdown and re-appears after lift-off.

2. When an engine fails in the air, the message disappears forever after touchdown.

3. When an engine fails on the ground, the message appears after lift-off.

4. When an engine fails on the ground, the message never appears, not even after lift-off.

(All statements imply all conditions for the message are true except for the on-ground condition which these statements handle individually.)


|-|

[United744]

My understanding was engine FAILURE is inhibited on the ground, because it is assumed someone is monitoring it and/or you will feel the asymmetry, or it is not critical (e.g. during taxi).

If you get airborne, you will then get the ENG FAIL message, but I seem to think this was linked to the fuel cutoff switch (placing the associated switch in CUTOFF clears the message, so it will not occur with a shutdown engine).

[Hardy Heinlin]

"Fuel not cutoff" condition is implied in the above conditions.

(All statements imply all conditions for the message are true except for the on-ground condition which these statements handle individually.)

That the fuel cutoff erases the message is obvious, otherwise you would get the message on every inflight start attempt when the ENG SHUTDOWN message disappears.

[emerydc8]

I can say for sure that on our sim when I was given an engine failure after V1, I would not get the warning caution lights or the beeper until 400' RA. Whether the EICAS showed up prior to rotating, I can't remember. I think it did. 

[John H Watson]

Whether the EICAS showed up prior to rotating, I can't remember. I think it did. 

The source of the logic for this message doesn't seem to be shown in the manuals. Whilst the message is listed in the FAFC section of the manuals, oil pressure is not sent to the FAFC. This means part of the logic is generated in the EIU. This makes tracking down the source of "in air" harder to do. Normally air/ground signals are generated by sensors on the landing gear, but some systems have air mode logic generated by other means. e.g. some parts of the electrical system define air mode as being 3 or more electrical generators above a certain rpm. However, if the ENG (X) FAIL message used this, there would be no ENG FAIL messages if more than 1 engine flamed out.

[emerydc8]

When you are a contestant/pilot in the sim, it's sometimes hard to recall at what point these EICAS alerts appear. I've asked a couple of friends and they're not sure either.

I think that when given an engine failure after V1, you will see the ENG FAIL EICAS well prior to reaching 400', even though the master caution and beeper won't occur until 400'. Whether the EICAS message happens when still on the ground or immediately after liftoff, I don't recall, but if I had to guess I would say it happened when still on the ground.

This is one of those questions that a certain sim instructor has probably observed hundreds of times.

[Hardy Heinlin]

When I played in the Lufthansa sims in the nineties, there was no such message; the LH pilot in the sim told me the first sign of an engine failure is the ELEC GEN message. -- I guess the ENG FAIL message has been added some years later, or it was available all the time and the pilot who told me that was just referring to ground operations.