747 - Climb on 2 engines?
 

Does the 747 takeoff performance cover the 2 Eng scenario?

I know if you loose two engines in flight their is a commital point on finals for a go-arounds .... so presume in the rare occasion of loosing two say at V1 or just after Vr it would not climb at heavey weights??

For most 3/4 engined beasties, the 2EI scenario addresses cruise only .. ergo, during takeoff, with a second failure, one is going to be very interested in

(a) gross weight .. dumping would be the norm

(b) configuration and speed ... usual to require a descent during which the aircraft is part/wholly cleaned up and a speed more useful than V2 achieved.

Definitely no guarantees in this situation ...

The 747 specialists will, no doubt, talk in respect of that machine ....

A few years ago in a 747-400 sim, we flew a profile that required one outboard failing after V1 and the adjacent engine failing at 1000ft above ground. This was at a sea-level airport at +28deg C and a weight of 380,000kgs TOW. As there was no terrain to consider, the aircraft was put into a shallow dive, to accelerate and the flaps retracted just below bug speeds. At the UP bug (approx. 265 kts) the a/c was allowed to climb until MSA achieved and then accelerated to 290 kts - where full manoeuverability to turn into the live engines was possible. A very interesting scenario which required precise handling, but the results were (for me at least) quite surprising. No fuel dumping took place during the exercise - it would have made, perhaps, only a reduction in weight of about 10 - 12,000kgs i.e 3-4kts.
Not something I would like to face in the aircraft, as PAX and hand-baggage often weigh more than the notional weights used for the loadsheet!

Purely hypothetical.
 

That's an interesting synopsis from 'skiesfull'.

But with respect to the original question: a sudden loss of two engines (on the same side?) I think the concern would be more towards the loss of directional control as the other two engines are developing near max thrust. In fact a thrust reduction *might* be in order.

In the case of two symmetrical engine failures, well, in that case you're not concerned with directional control. I submit that firewall thrust would be acceptable while realizing that any engine will exceed its limitation for a certain length of time. Those engines may never get used again, but at least maybe you can return in one piece.

Done it a few times in the sim. As skiesfull mentions, clean up is a interesting as when flaps are up you lose outboard ailerons and therefore full roll authority. We found it better to get some speed before going F up.

But when you're clean and at a decent climb speed (300 kts works) you will be able to climb (allbeit not very quickly).

Overall it handles quite well, not too dissimilar to a twin on one, but less performance and the go around scenario is a bit more complex.

Edited for spelling

Here's a textbook case in which the trainee cpt couldn't handle a DC-8 with two out during approach. (The NTSB brief has lost track of the fact 13 were killed in a motel)

Simulator fidelity has progressed to the point where you can rerun this scenario day in, day out and not hurt anybody (except a few egos).

I gues you are having a very bad day at heavy weights and at a hot/high airfield to loose 2 on one side ...

The only likely scenario is a multiple bird strike, or a uncontained blade that took out another eng.

Accelerating to clean up is logical ... I've been on type for 1.5yrs and their is no published procedure for this scenario, to the point of 'it wont happen' - never practiced it in the sim. (If if it can - it will is my theroy).

I've been faced with gear stuck down and an engine out (dispatch with 1 or 4 demand pump u/s and loose 1 or 4 eng respectively), the gear overide switch locks the gear lever ...
Heard it said gear stuck down is as good as loosing another eng. in terms of climb performance without the directional issues.

Simultaneous loss of two on one side during the early takeoff just about guarantees an up close and personal encounter with Mother Earth ...

But with a lot of luck.........

There was the Viscount training incident, where, having failed two on the same side, the crew ended the sortie by exiting--amid huge flames--out of a hole in the fuselage. Then they found themselves hopping from one 40gal drum to another. Yep, came to rest in the fuel farm.

Early 60s at SEN I think.

The only similar exercise I've done was in the sim when the instructor forgot to clear the previous #1 engine failure at V1 before he set up the #4 failure. I lost both at V1, but was able to get the airplane in the air (max TO weight). The scenario was LAX, standard day, taking off to the west over the water, so terrain was not a factor. The airplane accelerated VERY slowly, but it did fly.

Since an outboard engine failure at V1 in a 747 requires near full rudder to keep the airplane tracking straight, I suspect loss of both engines on the same side at V1 would not be controllable. VMCG is around 121-127 KIAS for the outboard engine failure, but I don't think the numbers are published for the 2-engine failure. Also, I doubt the Classic would have enough power to get airborne except at lighter weights (320T or less?).

For the 2-engine landing scenario, commit point is at landing gear down. While it is possible to get the gear up and climb away again, there is little margin for error.

I fly classics. Just got out of the sim. Our sim is ex-KLM and has 'R' powered Pratts on it; thats 54,000 lbs. of thrust each. During a max weight takeoff;833,000 lbs, full rudder trim is required + a bit of aileron to keep it straight.
I have not tried it on two engines/one side, but my firm belief is it would not be controllable. We do a two engine approach and landing scenario at max landing weight 630,000 lbs. and it is quite controllable. VMCG on an 'R' powered plane is 131 knots. V2 is 188 knots and it takes all 11,000 feet to get it off the ground on 3 engines with one quitting at V1. V1 was 157 knots.

A few years ago, our company lost 2 engines on a DC-8-61 coming out of France somewhere, and it was not pretty. However, there were two very experienced flight engineers on board and a rather crafty captain, and they survived.

I remember reading the narrative of the UAL 747 classic that lost two on the same side, along with a cargo door out of HNL in 1989. Pretty incredible read. Cant seem to find it anymore online.

The 747 was in mid-climb - see the NTSB brief

An explosive decompression is bad enough -- AND loosing no. 3 and 4 engines at the same time ... the crew did very well to contain the situation ....

It has happened to a BA classic coming out of somewhere in Canada (Montreal or Toronto I think). It hit a flock of geese and had to return. Can't remember the exact story, but was an interesting read, and I'm sure someone can give more detail.

The 400 has a lot more performance than the classic, but out of Canada it would have been at a relatively low weight so would have performed in a similar way to a 400 at 'normal' weights.

The notoriously underpowered C-5 has had two "one and a half" (one was gone and one was vibrating so badly power had to be reduced) failures after birdstrikes. Both got around OK, but rather hairly. At Dover in the early 80s, wx about 200-1/2, one took multiple geese, the A/C got it around barely a few hundred feet in the air, established a short PAR landed after being told, "too low for safe approach". One of two peacetime DFCs, I personally know.

The other at Westover, same scenario, double semi-failure during flap retraction, managed to land. Bad news was the nearly 200,000 pounds of munitions on-board. Got to close the dumps nearby the field. Good drivers, both, lucky too.

GF

Some airlines train for two out on one side as you hear the V1 call-out, attention to detail is reqd if you want to tell the story.
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Talking about Viscount, think I remember reading about one outer Heathrow in the 60s, engine failed during climb and crew shut down good engine on same wing by mistake(think locations of throttles and fuel cocks helped the mistake) crew avoided hi ground over Windsor and were able to tell the story to the CAA, well done to that crew!!!:)

A question from a genuinely interested beginner.
 

Does anyone train for three engines out in the 747?

EFATO or cruise?

I mean surely it is a possibility, however remote?

What is the response to three out?

I'm guessing from the posts above that it wont climb ... right?

Cheers,

ABX

OK, it wasn't a 747,

... but wasn't the RAAF 707 which went into the sea off East Sale (Victoria, Australia) in 1991 practising asymmetric climb-outs with two out? Result = :sad:

Those with long memories will recall a series of double engine failures on takeoff on BOACs VC10s in the 1970s, caused by debris from one failing engine entering the (very) adjacent one. All survived. Various flight profiles were tried out and later taught in the simulator to deal with such an event. Acceleration and clean-up at the expense of all else is the key. It says much for the Captain of the first one that he worked it all out as he went along.