787 engine failure procedure
 

just a quick survey for the 787 engine failure procedure. In my outfit, SOPs dictate that all take offs must be optimized therefore using assumed temperature and derate, and we follow Boeing's recommendation not to advance thrust levers or press to/ga after rotation.I find however that the performance after rotation is extremely limited. On the Sim climbing at 100 fpm until flap retraction only to see that the plane can climb at 1000fpm after CON kicks in doesn't feel right. Don't want to think how it feels on a hot day at MTOW in real conditions....Any comments, Ideas?

Assumed temperatures are calculated to satisfy the regulatory requirements of 2.4% (for a twin) in the second segment (gear-up to the commencement of flap retraction).

If you are doing 170Kts Groundspeed you should see at least 400'/min on the VSI, if not then obstacle clearance may be compromised.

The calculations in the OPT are all well and good but on the day, the wind may not be as forecast, the temperature may be warmer, the aircraft may be heavier, there may be an inversion, etc and the aircraft doesn't performance quite as expected.

When the performance isn't adequate, consider TOGA thrust.

I don't fly the 787, but have 17 years+ on Boeing twins. The B777-300 at MTOW is 'interesting' ;-)

Hi Straight and level....I fly both, and trust me, all well and good as you point out in performance theory, triple is not an issue. But the 787 on a combined ATM and derated take off FCTM states that in extreme conditions you may have altitude losses but overall the gradient is positive....well in VNAV you get 100/200 fpm until flap retraction and when CON kicks in your N1 goes up 10%....and ROC up to 1000 fpm or more

Dunno about the Boeing, but on the Bus side the recommendation is to leave FLEX unless performance is an issue - I think the main reason is the increase of thrust asymmetry and possibility of loss of control (I know, VMCA is calculated for TOGA and all that, but nevertheless, the workload increases). I can only imagine Boeing may have similar concerns.

Also, 100fpm you have cited is WAY too low on anything other than perhaps a Piper Seneca. Maybe this is some kind of sim problem, or performance calculation problem?

Sir Richard....would you happen to know why Boeing would recommend not advancing thrustlevers after rotation? Destabilizing or possible FMA mode complications?
Anyway in my neck of the woods we brief each other that when derated, we can press TOGA after an engine failure if needed and then set VNAV above 400".

Richard III. That is quite interesting, I didn't realise that the 787 was quite so limited. The same rules apply though, i.e. being able to achieve that 2.4% in the 2nd segment. If you are
consistently not achieving that (especially in the sim with a very predictable environmental model) then I would be concerned. I assume that you have rotated at the correct rate and are achieving V2 to V2+15Kts? I note that you are using assumed and derated thrust. You may start running into directional control issues if you increase thrust beyond the derate limit.

Maybe a question for your performance/tech department?

Sloopkogel.

VMCA issues if using Derated thrust. Assumed isn't a problem, but derated or assumed + derated is an issue.

Not allowed to hit toga as that removes the derate, climb 1or 2 as well as Assumed temp.
The derate lowers vmc I believe where as flex or assumed temp method doesn't, therefore you can increase thrust to the no ATM thrust setting safely, but if remove derate could in theory have vmc issues.....that is my limited understanding

My head used to hurt reading all those Airbus stories. Now my head is starting to hurt reading about the 787! :{

Dreamliner
 

Hope not a stupid question.

I am fascinated by the 787 pneumatics verse bleed air. In engine out, is there a consideration for the power available in the remaining engine as related to mechanical drag?

Well, the derate issue is not new and has been debated on these pages quite a bit. Usually concerning the somewhat smaller 737, but the performance issues are the same as is boeings advice.

Dear All...sorry for not stating the obvious...that the recommendation stems from VMCG/VMCA issues, but flying both 777/787 , the limited gradient that the 787 produces is quite notorious....in my previous outfit on the 777 we had a ballpark v2 that we used in case we thought performance was compromised and then hit toga if necessary which seldom is on the triple...
now a gradient of 100/200 fpm up to a 1000 feet only to have CON kicking in and achieve 10% more power and a 1000 fpm rate IMHO deserves further study, its just not natural, quite the opposite, steeper gradient to a 1000 feet, then accelerate to clean up...
open to corrections and comments on this

Richard 111

A "ball park v2" what is that ? Either there is a correct V2 or there isn't. If you were using de-rate take offs on the 777 then if you select TOGA you will likely crash. Which is why Boeing say don't do it. A new VMCA is calculated using the selected de-rate. You will run into controllability issues if you push TOGA on the remaining engine. Assumed temperature can be cancelled without an issue so you may push the thrust levers forward but only to the de-rate limit which is why you have the show full option on OPT. Your company should revise that SOP with the Boeing technical team. The 787 is identical to the 777 in this regard although it also has TAPS/TAMS to try to stop you crashing.
So to summarise if you takeoff with De-rate and ATM combination you may disconnect the A/T and push to the selected De-rate limit only......but NOT TOGA ! Yes the 787 has a drastic drop in performance with an EFATO compared to the 777 but it is all still compliant with the regulations if you fly it correctly. The 777 has more margin but then its a 26 year old design and designed for anything from 155 to 351 ton take off. The 787 is strictly a min fuel burn machine.
By the way our E/O acceleration is 1500 AGL so it can be a very long wait on the 787

There's a test pilot doc on TAPS here https://www.tib.eu/en/search/id/BLCP...ection-System/

8che, sorry if it wasn't clear...Ballpark v2 means a V2 thats above the maximum VMCA...in this case if I remember well was 141 knots. If you are above that you will never have controllability issues..
BTW the 777 does not have TAPS/TAMS...what it does have is a TAC, different beast altogether.
Wether you like it or not my opinion is that the procedure on the 787 can be improved, and whilst marginal, it is within regulatory limits, not arguing about that, then again thats my take on it, reason why I am looking for different opinions on this....
PB...thanks for link, I know one of the authors and certainly is a good piece of info...

I am very familiar with both 787 and 777 aircraft and still fly both which is why I highlighted the additional features of TAPS/TAMS which the 777 does not have.

We are not in disagreement with performance. It is marginal but many turboprops are a lot worse. At least the 787 does not have a TAC that drops out with severe engine damage as per the 777.

I'll suggest again...do you have the "SHOW FULL OPTION" on your OPT ? If you do then you have acceptable means of compliance to manual increase thrust to that level where ATM is cancelled but the Derate thrust setting is not exceeded. That is the solution given from Boeing

My only query is how on earth Boeing FCTM comes up with typical engine out pitch guidance of 12 degrees (2 to 3 degrees less than normal) for initial setting. Anything more than about 8 and its good bye V2 for the 787 and similarly 10 for the 777

And I used to do something very similar. I'd run an OPT calculation with no derate and take note of the V2. Should anything ever happen, I then had a safe V2 speed at hand to accelerate to if desired with certainty VMCA would never be an issue. I would however never advocate trying to accelerate to the higher speed if there was a significant difference between the two; in that case just have to live with it

"My only query is how on earth Boeing FCTM comes up with typical engine out pitch guidance of 12 degrees (2 to 3 degrees less than normal) for initial setting. Anything more than about 8 and its good bye V2 for the 787 and similarly 10 for the 777"


I wonder if that statement relates to a MAX PWR takeoff? 12 degrees for MAX PWR, 10 degrees for derated takeoff?

During my conversion to the 787 at Boeing they emphasised not to increase power past the fixed derate in the event of an engine failure on takeoff. However, they also suggested that once the speed was more than 149kts VMCA was not a problem.
They also never mentioned the 12 degree target attitude after an engine failure but rather stressed to pitch to the TOGA Reference Line in the HUD which would always be correct. Experience would suggest that they were right.

"And I used to do something very similar. I'd run an OPT calculation with no derate and take note of the V2. Should anything ever happen, I then had a safe V2 speed at hand to accelerate to if desired with certainty VMCA would never be an issue."

I am struggling to find a performance calculation with varying conditions and weights where there is a difference between V2 at either FULL or ATM more than a knot or two. In most cases its the same.

Acknowledging my inexperience on the aircraft, am I missing something?