Q: Braking on a passenger twin when landing with an engine out
 

I've been following Boeing door threads, including the one about Mayday call procedure, I watched the video that was linked to, where they had a bird strike on takeoff at Manchester. They asked for a brake inspection on landing, the fire crew seemed to concentrate on the RHS, the side with the failed engine. That set me wondering - when landing a modern passenger twin with an engine out, do you still use reverse thrust on the good engine? If so, will the braking system automatically compensate for the asymmetric braking force, or does the pilot have to take care of that? Thanks :8

Boeing here. The Autobrakes are set to deccelerate you at a constant rate. The speedbrake and reversers act to assist so that the brakes don't have to work as hard. At light weight and auto brake 1 or 2 the braking effect of reversers can exceed that of the brakes meaning they do very little and stay cool. At higher weights and brake settings the brakes will stop you quicker than the reversers could so use of reverse thrust will not stop you any sooner but they will assist and help keep the brakes cool. Landing with no reversers would concentrate all the kinetic energy onto the brakes which can lead to brake fires and deflated tyres when hot/high/heavy. Landing single engine we would use the remaining reverser on the good engine, controlling direction with the rudder then nose wheel. Here's where my knowledge runs out but I would expect despite the asymmetry that the reverse 'effect' would be shared equally between the brakes.

Ah yes, I'd forgotten about the speedbrakes - just as well I'm kept well away from the pointy end :O

When you say "rudder then nosewheel", I assume that means using a tiller? Is there a set crossover speed between rudder & tiller for each aircraft type?

Sorry, lots of SLF Q's, the clue is in the user name :p But thank you for the answer :ok:

The pedals control both the rudder and small amount of nose wheel. The tiller controls the nose wheel through a much larger range of motion and is generally used during taxi and for tight turns, although the pedals can be used to keep it straight on a taxiway.

The OP may be interested to know that some aircraft can completely automatically track the runway center line after landing. These aircraft can roll to a stop with no pilot input on brakes, rudder pedals, or tiller.

The required equipment is a Category III automatic landing system with ground rollout mode. Since most such systems depend on the ILS localizer the system is normally only used when the ILS is "protected" from disturbance by aircraft or other equipment moving on the airport surface.

Also, as they had just departed the ac would be heavier compared to the end of the planned flight and also they would land with less flap (F20 prob) and thus a higher landing speed. So more weight and speed than usual, more mv squared kinetic energy to be absorbed by the brakes.

Speedbrakes - they do have a drag function, but also kill the lift from the wings, thus putting the weight onto the wheels earlier and making the brakes more effective.

hth

Do not over estimate, misjudge the risks from using max braking. The hazards are still there, but probably less than trying to juggle unfamiliar asymmetric reverse, high speed nose wheel steering, and cross control of rudder.

Certification requires demonstration of a maximum energy rejected takeoff, max wt, worst case hot and high airport.
So even if your aircraft mass was near these conditions, then the landing configuration should result in a lower speed, Vref less than V1 - sufficient to counteract loss of reverse.

Feh, even my car can do that :}

As an interesting aside, it even seems to know which lane I'm in - I don't think GPS is accurate enough for that, I suspect it's done by the lane following camera.

Thanks to everyone who took the time to reply, lots of interesting stuff that I didn't know.

We will give ATC a heads up on that we would need the fire brigade to check on the brakes for these reasons. The fire brigade does check both sides, however they do that from a distance. The fact they are walking that close probably means they feel the situation is low risk (otherwise you would see smoke and maybe the red glow). There is also human curiosity at play to see the damaged engine once the aircraft is confimed not too move.

They did, several times. Plus telling them that the left engine would be running. And one of the firemen did have a nosey inside the dead engine as well :)

Do the brakes have temperature sensors on them? I assume nowadays the fire crew would have IR imaging kit that would give them an accurate temperature anyway.

I though the video was very impressive, a bird strike literally as it they leaving the ground yet no muss, no fuss. For anyone who is a nervous flyer, I'd think watching it could help reassure them that even with an engine gone, the plane can take off, fly and land safely, and that everyone involved is trained in exactly what to do.

Interesting. How much test data do you have available? I didn't know cars could track a runway center line, typically they are only smart enough to keep between highway lane markings.

Some do, but not all. On some models, brake temp monitoring is an extra cost option, others have it basic - in short 'it depends'.
Engine out landing is usually done with a reduced flap setting and hence higher speed (among other things, it's helpful for go-around performance if needed). The concern in this case was, they had just taken off and were heavy with fuel - possibly overweight for landing depending on the fuel and payload.

That's an interesting reason - "obviously right" - just as soon as someone has told you it! It hadn't occurred to me that you might have to do a go-around after an engine failure, but of course you might.

Indeed and this is practised every 6 months in the sim - single engine approach, go around, landing.

Putting some flesh on the bones ....

The Thomson ac is a 757, so here are some numbers with lots of rounding for simplicity. Let's go for a heavy take off (110T) with a planned landing at 90T after a 4-5 hour flight, so Turkey, Canaries etc. All airfields at sea level, temp +15deg, still wind, standard pressure (1013hPa), dry runway.

Planned landing, Flap 30, 90T, Vref 132 kts. Autobrake 2 landing distance 7500'
Actual landing, SE, F20, 110T, Vref 159 kts. Lots more energy involved in stopping this thing. A/B 2 landing distance 9000'.

Using the brake cooling tables, the heavy ac has approx 50% more energy to dissipate by drag, reverse and brakes.

rgds

It's almost as if Aviation is a pretty mature industry where people have spent time thinking about this sort of stuff, and training for it ;)

Thanks again to all the people who earn their crust doing this stuff on a daily basis and to who these questions might be a bit "Duh!", but have still taken the time to answer, much appreciated. :ok:

There is a note in the 747 manual regarding performing a landing with two engines out on the same side - don't recall the exact wording but the jest of it is "Go-Around from final approach is not recommended". Don't remember it this was noted in the manual, but the go-around thrust setting was less than takeoff because - with two engines out on the same side - if you set takeoff thrust you'd run out of rudder...
Every time I'd see that, I'd think "Two engines out on one side, then having to do a go-around? Talk about having a bad day!"

Was it a People's Express or Continental 747-200 that lost power on both left hand engines due to turbulence off hangars while taking off from Gatwick in the 1980s? Struggled over Russ Hill, friend was working in Newman House and said it disappeared from view behind the trees and they waited for the eruption of black smoke...

N605PE 1st Feb 1988. Only no. 4 engine lost thrust.

Just the one? And right side... Blimey...