Double engine failure turnback
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Slash ... sometimes the FotoTime site goes down for short periods. It could be that the photo is already on there, just not yet showing up. Go into the relevant album as "yourself" and do a "refresh". That usually works for me.
If all else fails, if the file ain't tooooo big, send it to me and I'll try putting it up on my FotoTime site.
If all else fails, if the file ain't tooooo big, send it to me and I'll try putting it up on my FotoTime site.
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Thanks Ozex but it now appears the problem is in the read-outs themselves. I obtained both the lateral and vertical profile diagrams as a print-out and had to scan each and save in jpg format. Fototime has them ok (file-size is correct) but its just too damn bloodey faint to be anything ledgable.
Sim-consoles bamboozle me even during the best of times and there was no tech guy around to help me directley save them to a floppey or anything.
Sim-consoles bamboozle me even during the best of times and there was no tech guy around to help me directley save them to a floppey or anything.
Last edited by Slasher; 8th May 2002 at 08:10.
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That's a real shame Slash, coz now ya'll just havta go and do it all again! 
But, hey, ya came up with a very good number that surprised me beyond belief. Of course, the operative expression is - as you said - "if your actions are immediate". Don't think I'd like to be the one putting it to the test tho!
As it's in the same ballpark as the results notified by tijm, it would seem that you both went about the test in pretty much the same way. Is your sim configured as a -300? I can't look that far back on the thread while writing this reply.
But, hey, ya came up with a very good number that surprised me beyond belief. Of course, the operative expression is - as you said - "if your actions are immediate". Don't think I'd like to be the one putting it to the test tho!As it's in the same ballpark as the results notified by tijm, it would seem that you both went about the test in pretty much the same way. Is your sim configured as a -300? I can't look that far back on the thread while writing this reply.
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Yeh but Ozex we simulated an actual everyday TO with only minor variations as per that "recap" list above. Tij said he left the APU running. Most Companys require the APU off after engine start (save fuel etc) unless you require it on for certain MEL reasons (busted engine generater, engine bleeds-off TO, etc). So we turned it off after start. When engine-driven AC electrics died all we had left was the battery and it takes too bloodey long to start the APU and get its genny on one of the main busses before scraping the treetops.
Also Tij dropped the gear, where our profile left it up and we belly-landed. This obviousley led to our lower figure of 1350 ft as against his 1500-2000 ft. And WWW did ask what was the minimum height to make a 180 and get in.
PS Yeh actions have to be done asap alright, and yeh its a 300. And we tried startin the APU but it didnt fire up and have its genny available until we were slidin around on the deck showerin sparks everywhere.
Also Tij dropped the gear, where our profile left it up and we belly-landed. This obviousley led to our lower figure of 1350 ft as against his 1500-2000 ft. And WWW did ask what was the minimum height to make a 180 and get in.
PS Yeh actions have to be done asap alright, and yeh its a 300. And we tried startin the APU but it didnt fire up and have its genny available until we were slidin around on the deck showerin sparks everywhere.
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Sim trial
I tried the 500' & 1000' agl engine loss after takeoff with
Cessna 172 & 182 models on MS 2002. The 172 crashed
short both times
, while the 182 got back to the runway
just on the 500' and easily on the 1000'
. I think the
key is the difference in best rate of climb, the 182 was
showing 1500fpm while the 172 was more like 500fpm.
So given a 90-knot best climb for the 182 a 1000' fail was
taking place within a mile of the runway, while the 172
at 75-knots was failing at 2.5 miles.
All in all a good argument for climbing to en-route altitude
as rapidly as you can...and having a powerful engine to start
with.
Of course this is MS software so your mileage may vary.
-- Andrew
Cessna 172 & 182 models on MS 2002. The 172 crashed
short both times
, while the 182 got back to the runwayjust on the 500' and easily on the 1000'
. I think thekey is the difference in best rate of climb, the 182 was
showing 1500fpm while the 172 was more like 500fpm.
So given a 90-knot best climb for the 182 a 1000' fail was
taking place within a mile of the runway, while the 172
at 75-knots was failing at 2.5 miles.
All in all a good argument for climbing to en-route altitude
as rapidly as you can...and having a powerful engine to start
with.
Of course this is MS software so your mileage may vary.
-- Andrew
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Interesting thread.
I have often wondered about this one when flying jets/tugs/gliders. I see the major problem when you are flying 'faster' aircraft as being restricted as to the rate of turn you can achieve in order to get pointing back towards the airfield. This automatically positions you some distance from the runway, and leaves you flying for some time at high rates of descent.
Problem: You want to reverse the direction of the a/c using the minimum distance, and in the shortest possible time.
Possible solution: If you were an aerobatically inclined pilot with vitals of steel, you might consider a cross between a stall turn and a chandelle, depending on height/speed available. If you 'unload' the wings during the manoevre, you can fly as slowly as you like. You could 'flop over the top' as long as you pointed towards the ground for a bit afterwards to get speed back for conventional flight. The turn rates for this trick would be much higher than using a normal 1.x Vs turn or whatever, and because you would not be asking the wings to generate vast quantities of lift for extended periods, probably quite efficient in overall energy terms. It would also leave you pointing almost directly down the runway.
Maybe one of our aerobatic aces could try this at altitude and report on the height losses etc.
I have often wondered about this one when flying jets/tugs/gliders. I see the major problem when you are flying 'faster' aircraft as being restricted as to the rate of turn you can achieve in order to get pointing back towards the airfield. This automatically positions you some distance from the runway, and leaves you flying for some time at high rates of descent.
Problem: You want to reverse the direction of the a/c using the minimum distance, and in the shortest possible time.
Possible solution: If you were an aerobatically inclined pilot with vitals of steel, you might consider a cross between a stall turn and a chandelle, depending on height/speed available. If you 'unload' the wings during the manoevre, you can fly as slowly as you like. You could 'flop over the top' as long as you pointed towards the ground for a bit afterwards to get speed back for conventional flight. The turn rates for this trick would be much higher than using a normal 1.x Vs turn or whatever, and because you would not be asking the wings to generate vast quantities of lift for extended periods, probably quite efficient in overall energy terms. It would also leave you pointing almost directly down the runway.
Maybe one of our aerobatic aces could try this at altitude and report on the height losses etc.
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Hmmmm - I can just see the Aresti diagram...
Extra points for not falling off the top of the loop, keeping within the box and not wiping any of the pax across the top of the cabin!
I know that both Barry Tempest and Brian Lecomber subscribe to PPRuNe... maybe one of them might break cover!? Or Louisa? You out there?
Extra points for not falling off the top of the loop, keeping within the box and not wiping any of the pax across the top of the cabin!
I know that both Barry Tempest and Brian Lecomber subscribe to PPRuNe... maybe one of them might break cover!? Or Louisa? You out there?
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WWW are you interested in this thread you started or not pal?
I get a bit annoyed when someone asks a question, someone takes the time to duly investigate it, only to find the original enquirer has disappeared like a fart in the wind and couldnt give a stuff.
I have techniques, speeds, bank angles etc used in that sim exercise if your still interested WWW. If your NOT interested then I will ignore ANY further threads you start from hereon.
I get a bit annoyed when someone asks a question, someone takes the time to duly investigate it, only to find the original enquirer has disappeared like a fart in the wind and couldnt give a stuff.
I have techniques, speeds, bank angles etc used in that sim exercise if your still interested WWW. If your NOT interested then I will ignore ANY further threads you start from hereon.
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Slasher,
I’m sure many would like to see the data, not only 3W. I was very excited about your research and ran home early to catch your post about the results. So, while the originator of the thread may have lost enthusiasm, more fill the void.
Still I hear what you’re saying: It is a pain to compose responses and it’s time intensive in general. Of course, you went beyond the normal post and did independent research. You have a right to feel unappreciated, the feedback you have received has been paltry (Expat Excluded). However, your work may save my scrawny neck sometime, and possibly others. Many will read your words of wisdom, and some will put into practice your hard borne experiences. In aviation we learn vicariously, there are too many mistakes out there to make them all individually. But, data is proprietary, it is your choice to disseminate.
Anyway I wish to extend my thanks for the work which you have already submitted, it has enlightened my sense of possibilities, and awakened within me a realization that this is not as easy an exercise as one might be initially led to believe.
Safe flying
I’m sure many would like to see the data, not only 3W. I was very excited about your research and ran home early to catch your post about the results. So, while the originator of the thread may have lost enthusiasm, more fill the void.
Still I hear what you’re saying: It is a pain to compose responses and it’s time intensive in general. Of course, you went beyond the normal post and did independent research. You have a right to feel unappreciated, the feedback you have received has been paltry (Expat Excluded). However, your work may save my scrawny neck sometime, and possibly others. Many will read your words of wisdom, and some will put into practice your hard borne experiences. In aviation we learn vicariously, there are too many mistakes out there to make them all individually. But, data is proprietary, it is your choice to disseminate.
Anyway I wish to extend my thanks for the work which you have already submitted, it has enlightened my sense of possibilities, and awakened within me a realization that this is not as easy an exercise as one might be initially led to believe.
Safe flying
Last edited by '%MAC'; 14th May 2002 at 06:53.
G'day Slash,
Now for a variance to your configuration:
What's the minimum height needed to land back on with the wheels down?
As an aside, I haven't a clue how long it takes to get the gear down on a 737. Is it longer than the time it took to land back on from the double failure in your previous experiment or is it shorter?
All other conditions the same as your first effort.
Now for a variance to your configuration:
What's the minimum height needed to land back on with the wheels down?
As an aside, I haven't a clue how long it takes to get the gear down on a 737. Is it longer than the time it took to land back on from the double failure in your previous experiment or is it shorter?
All other conditions the same as your first effort.
Thread Starter
Yeah I'm still here Slasher. Thank you for using a sim to investigate my question. You answered my question - 1,350ft.
If you could clarify just how you flew the manouvre that would be great. I am guessing the gear down would have cost a couple of hundred feet...
Cheers,
WWW
If you could clarify just how you flew the manouvre that would be great. I am guessing the gear down would have cost a couple of hundred feet...
Cheers,
WWW
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Ok then.
Unfortunatley we didnt have enough sim time to go through various configuration and weight scenarios such as gear down and lighter (46T) gross weights. We therefore stuck to a gear-up landing as this would dictate the minimum height for a return, which was your original question WWW. Various heights were experimented. 1000 ft was not enough and 1500 ft was an overkill.
Please refer to my previous "Recap" for aircraft configuration and status before TO.
* Upon the double engine-failure the stick must be IMMEDIATLEY pushed forward from 21 deg NU to at least an initial 5deg down, while at the exact same time violentley initiating (yes even though your picking up your into-turn flight spoilers at that point), then smoothley executing, a turn at 50 deg AOB while increasing speed to vref 5 (168kt). With 22% MAC the nose was quite agreeable to pitch down and increase speed at that bank angle which required only a .1 unit stab-trim input ND once at wings-level. In our exercise I overshot slightly to 172 kts IAS on the standby ASI but letting go the stick at that point was beneficial and 168 kts was quickly regained.
This manouver is the most costly of the exercise in terms of height. Rollout in intercept heading (about 30 deg) was at a height of 320 ft.
*APU start-attempt was tried, but as predicted we were alreadey on deck by the time the genny was avbl. So no AC electrics around throughout.
* Auto-activation of the standby hyd system valves had occured but the pump itself of course was dead.
* Around 2 deg ND (as read from the Standby AI) was necessary to maintain Vref 5. I was quite surprised at this as I thought 3-4 would be required.
* About 60 deg before intercept-heading rollout we were on manual reversion. This is why the initial manouver must be flown quickly and relativley violentley in order to utilise the flight controls before you lose all hydraulic sys A+B pressure. Of course from then on you fly rudder for bank and stab-trim for pitch where possible as you well know.
* Rollout on final was at 50ft, just in from the piano-keys. Flare and landing as per gear-up procedure in the Boeing FCTM.
Summary: If the crunch comes in real life Id recommend absolutley no lower than 1500 ft in height if your hard decision is to turn back. In our exercise no recognition time was allowed which of course is about 2 secs, and another 1 second to initiate the required action even assuming your wide-awake. Anything lower than 1500 ft Id aim straight ahead and pick a road or aim in between the houses or cows.
Notes: In our aircraft, standby pump only powered by xfer bus 2 (or 1 through the xfer sys) and FMC is not avbl when battery and standby inverter are only sources of power.
Unfortunatley we didnt have enough sim time to go through various configuration and weight scenarios such as gear down and lighter (46T) gross weights. We therefore stuck to a gear-up landing as this would dictate the minimum height for a return, which was your original question WWW. Various heights were experimented. 1000 ft was not enough and 1500 ft was an overkill.
Please refer to my previous "Recap" for aircraft configuration and status before TO.
* Upon the double engine-failure the stick must be IMMEDIATLEY pushed forward from 21 deg NU to at least an initial 5deg down, while at the exact same time violentley initiating (yes even though your picking up your into-turn flight spoilers at that point), then smoothley executing, a turn at 50 deg AOB while increasing speed to vref 5 (168kt). With 22% MAC the nose was quite agreeable to pitch down and increase speed at that bank angle which required only a .1 unit stab-trim input ND once at wings-level. In our exercise I overshot slightly to 172 kts IAS on the standby ASI but letting go the stick at that point was beneficial and 168 kts was quickly regained.
This manouver is the most costly of the exercise in terms of height. Rollout in intercept heading (about 30 deg) was at a height of 320 ft.
*APU start-attempt was tried, but as predicted we were alreadey on deck by the time the genny was avbl. So no AC electrics around throughout.
* Auto-activation of the standby hyd system valves had occured but the pump itself of course was dead.
* Around 2 deg ND (as read from the Standby AI) was necessary to maintain Vref 5. I was quite surprised at this as I thought 3-4 would be required.
* About 60 deg before intercept-heading rollout we were on manual reversion. This is why the initial manouver must be flown quickly and relativley violentley in order to utilise the flight controls before you lose all hydraulic sys A+B pressure. Of course from then on you fly rudder for bank and stab-trim for pitch where possible as you well know.
* Rollout on final was at 50ft, just in from the piano-keys. Flare and landing as per gear-up procedure in the Boeing FCTM.
Summary: If the crunch comes in real life Id recommend absolutley no lower than 1500 ft in height if your hard decision is to turn back. In our exercise no recognition time was allowed which of course is about 2 secs, and another 1 second to initiate the required action even assuming your wide-awake. Anything lower than 1500 ft Id aim straight ahead and pick a road or aim in between the houses or cows.
Notes: In our aircraft, standby pump only powered by xfer bus 2 (or 1 through the xfer sys) and FMC is not avbl when battery and standby inverter are only sources of power.
Last edited by Slasher; 15th May 2002 at 07:50.
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Slash... I guess it's also true to say that you were ready for this simulated emergency. How many pilots would ever be quite THAT ready for such a situation? I guess that, if you have the opportunity again in the near future, can you try a few seconds delay ... to simulate the standard first call in the emergency checklist - Sh!t... WTF was THAT??!
Perhaps end up needing something more like 1800 FT eh? But then I'm guessing you may run into the "tyranny of distance" problem in getting back to the runway...
Perhaps end up needing something more like 1800 FT eh? But then I'm guessing you may run into the "tyranny of distance" problem in getting back to the runway...
Thread Starter
Slasher - v interesting. Many pilots I talked to about this thought it impossible below something like 3 - 4,000ft.
I might have a go at your profile myself if I can get 5 spare minutes at the end of a sim detail.
Cheers,
WWW
I might have a go at your profile myself if I can get 5 spare minutes at the end of a sim detail.
Cheers,
WWW
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Slash... As you know, I'm not rated on the 73, but I'm interested in that bit about using stab trim for manual reversion. Are you referring to electric or manual trim? I'd have thought that electric stab trim wouldn't be available with a total loss of AC.
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Thats a very perceptive question Ozex considering your not even rated on type! Arent you the smart cookie!
Yes mate you are correct. Electric stab trim isnt available with a loss of AC, so physical manual movement of the stab trim wheel is necessary. As any 737 driver will tell you the elevator is very heavey in manual reversion and stab trim helps augment control in pitch.
Hmmm while on the subject, WWW would you happen to know which bus powers electric stab trim? We know rudder and aileron trims are off AC Xfer Bus 1, but Im not sure of stab trim.
PS Oh and Ozex your "what the faaaaark!" factor was mentioned by me earlier referance the 2 + 1 secs recognition in my "Summary" paragraph.
Yes mate you are correct. Electric stab trim isnt available with a loss of AC, so physical manual movement of the stab trim wheel is necessary. As any 737 driver will tell you the elevator is very heavey in manual reversion and stab trim helps augment control in pitch.
Hmmm while on the subject, WWW would you happen to know which bus powers electric stab trim? We know rudder and aileron trims are off AC Xfer Bus 1, but Im not sure of stab trim.
PS Oh and Ozex your "what the faaaaark!" factor was mentioned by me earlier referance the 2 + 1 secs recognition in my "Summary" paragraph.
Very interesting thread. I can only comment on turnbacks I have practised in the military (Tucano/Hawk) many moons ago. I believe the Air Force has now stopped practice turnbacks after a couple of nasty accidents.
Notwithstanding the urgent need to get the aircraft back from whence it came, there are inherent dangers with turning directly towards the runway, funnily enough. Firstly, many people try to turn way too hard to get back to the centreline as quickly as possible, with the risk of stall/wingdrop - remember you only have 2 things in your favour, speed and height...turning too quickly washes off the former thereby losing the latter more quickly. Secondly, the final alignment turn is done perilously close to the ground at low speed which is another cause for concern. Slasher's roll out at 50ft is a case in point.
Now (I hope I can remember this correctly!) on the turnbacks I was taught, the first thing to do was to actually turn away from the runway! This allows you to do 2 things - see the runway before you turn back sooner and set the aircraft up for the turn -Vimd usually worked. I'm not saying a prolonged outbound leg, but enough to get you a little displacement to execute a decent turn.
I only proffer this up as food for thought. There will be those that say that you are wasting energy going in the wrong direction - I don't know the answer. Perhaps you may need more height for the manouevre - maybe someone can try it out in the sim (My next one's in Aug....so you'll have to wait for the Airbus answer!!!)
TSP
Notwithstanding the urgent need to get the aircraft back from whence it came, there are inherent dangers with turning directly towards the runway, funnily enough. Firstly, many people try to turn way too hard to get back to the centreline as quickly as possible, with the risk of stall/wingdrop - remember you only have 2 things in your favour, speed and height...turning too quickly washes off the former thereby losing the latter more quickly. Secondly, the final alignment turn is done perilously close to the ground at low speed which is another cause for concern. Slasher's roll out at 50ft is a case in point.
Now (I hope I can remember this correctly!) on the turnbacks I was taught, the first thing to do was to actually turn away from the runway! This allows you to do 2 things - see the runway before you turn back sooner and set the aircraft up for the turn -Vimd usually worked. I'm not saying a prolonged outbound leg, but enough to get you a little displacement to execute a decent turn.
I only proffer this up as food for thought. There will be those that say that you are wasting energy going in the wrong direction - I don't know the answer. Perhaps you may need more height for the manouevre - maybe someone can try it out in the sim (My next one's in Aug....so you'll have to wait for the Airbus answer!!!)
TSP
Last edited by The Scarlet Pimpernel; 19th May 2002 at 16:11.