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On this answer, there is a comment that asks if there is an alerting alarm of some sort when an engine falls off an airplane.

Is there a direct alarm from the engines specifically saying "You lost an engine" to warn that an engine has fallen off from the aircraft?

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  • $\begingroup$ Do you mean that question literally? Would you accept, "No, there is no alert"? If that is not an acceptable answer, why'd you ask the question? $\endgroup$ – abelenky Mar 4 '16 at 17:26
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    $\begingroup$ You need to be careful when asking for evidence to disprove something. I believe that there is a teapot orbiting Jupiter. Please provide evidence that there is not. I recommend re-wording your question along the lines of "do any aircraft have an engine-off alarm?" $\endgroup$ – Simon Mar 4 '16 at 17:32
  • $\begingroup$ Do you mean an alerting system to indicate that an engine has literally departed the aircraft—as you said, when an engine falls off an airplane—or do you mean an alerting system for an engine power failure? $\endgroup$ – J Walters Mar 4 '16 at 18:29
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    $\begingroup$ In modern airliners, there are up to 853 independently triggered engine-off alarms, although oddly enough, they are never present on cargo versions. $\endgroup$ – Sanchises Mar 7 '16 at 13:41
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    $\begingroup$ This question is not duplicated. This one is asking if there is an alarm if the engine is lost, the previous discusses about what happens with the fuel lines. They are related, but not the same question. $\endgroup$ – Trebia Project. Apr 5 '16 at 8:41
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This is the indicator that shows you when one engine falls off in a multi-engine aircraft:

enter image description here

If the right engine falls, off, the little ball will move left. If the left engine falls off, the little ball moves right.

If you only have one engine, or both engines fall off, you need to use a different indicator that looks like this:

enter image description here

if both engines fall off, this white pointer will start to move towards the "40", and you might hear an alarm, a voice shouting "stall, stall", or feel the stick shake.

if you have one engine and it falls off, the white pointer will move, but in an indeterminate direction.

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    $\begingroup$ A superior pilot using his superior skills would immediately apply corrective rudder to keep the ball in the middle and begin a descent to keep the airspeed at a minimum safe speed. :) $\endgroup$ – Mike Sowsun Mar 4 '16 at 18:13
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    $\begingroup$ it only works on the ground, but there is a little button on the yoke that says "transmit". if you press that button and ask for "maintenance", you can request that they jettison the engine. $\endgroup$ – rbp Mar 4 '16 at 18:14
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    $\begingroup$ @rdp "maintenance" has this nasty habit of putting another engine back on when you aren't looking though. $\endgroup$ – Zach Lipton Mar 4 '16 at 19:09
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    $\begingroup$ My airplane doesn't have either of those instruments.... $\endgroup$ – Lnafziger Mar 4 '16 at 20:59
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    $\begingroup$ There are a couple of design flaws in that first instrument that have been there since multi engine aircraft first flew. The first is that if the engine blows itself to pieces, but stays on the airplane, the indicator still shows that it has fallen off. The indication is the same! The second is that in every aircraft I've ever flown, I've drilled a little hole in the glass to let that bubble of air out and it's stopped working. Surely modern technology can overcome these problems? $\endgroup$ – Simon Mar 4 '16 at 21:02
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The B-737 has a checklist for engine separation, but no specific alarm for it. The absence of all engine indications might be a hint, though.

I've never heard of any aircraft with such an alarm, but I don't know about all of them out there.

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    $\begingroup$ Presumably the loss of that engine's monitoring data would trigger an "alarm" of some kind (at the very least the master caution will be tripped, along with probably every fault that engine can show on the EICAS display) $\endgroup$ – voretaq7 Mar 4 '16 at 18:50
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    $\begingroup$ I think any pressure sensor (for an aircraft that has one) would reside in the (now departed) engine, rather than upstream. If anything, the fuel FLOW sensor, IF it's still attached to the aircraft, would show a fairly high rate of flow. The checklist on my aircraft directs pulling the fire handle, which among other things closes the spar fuel shutoff valve, which does stop fuel from streaming out. $\endgroup$ – Ralph J Mar 5 '16 at 21:11
  • $\begingroup$ @voretaq7: Only the master caution?! I would more expect an engine separation to trigger the master warning... $\endgroup$ – Sean Apr 7 at 1:02
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    $\begingroup$ @Sean The only "master warning" on the 737 is the fire warning, and an engine separation most likely wouldn't trigger that. The separation itself isn't a Master Caution event, but things like the generator now being off-line (in more way that one!) would probably trigger the associated master caution alert. $\endgroup$ – Ralph J Apr 7 at 1:10
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aircraft work a bit different when it comes to alarms and advice. There is indeed an alarm and an indication of an engine failure. You would notice that the indicators of the respective engine, like Exhaust Gas Temperature (EGT), N1 Thrust and N2 Thrust will all drop. You will also get an EICARS warning (or several), that lead to the conclusion, that indeed an engine has failed. There is yet another indication if there is an engine fire. Along with an alarm the engine fire extinguisher handle will light up.

However, there is no indication as of whether the engine has just failed or flamed out or separated. At least not from an instrument point of view. A good pilot however will at least suspect that an engine separation has occurred. For example, if an engine is failing, its indicators are going down slowly. N1, N2, fuel flow, everything is going down slowly until it reaches zero. An engine separation will also lead to a fuel leak, since the fuel will spill out of the pylon. Maybe there also have been engine issues before, like overheating, that led to the failure. On the other hand, if an engine separates, all indicators will go to zero pretty much right way. As all sensors are gone. Usually a missing engine will also change flight behavior. Another way to find out would be the cabin crew or a passenger telling the flight crew. Of course this does only work with wing mounted engines. Aircraft like the Boeing 717, which have tail mounted engines make it impossible for anyone in the cockpit or cabin to notice a separation. In addition, it helps to know what happened before... maybe a sound of an explosion, touching something with the wing, etc. would also lead a pilot to think that an engine could have been separated.

So to summarize: There is an alarm for engine failure and engine fire but there is no alarm for an engine separation. It will just be an engine failure alert. However, there are indications and signs which a good pilot will recognize to at least suspect the separation.

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    $\begingroup$ On a DC9/MD80/MD90/MD95/B717, you can see the front of the engines from the rearmost cabin windows, so separation would be easily noticed by passengers and cabin crew. $\endgroup$ – StephenS Nov 3 '18 at 20:47
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    $\begingroup$ Good point. Maybe.. I never been in one neither as pilot nor as passenger. Thanks for letting me know. Learned something new. $\endgroup$ – BenjB Nov 4 '18 at 0:03

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