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Aeroflot deactivates brakes on nine aircraft, relies solely on reverse thrust

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Re: Aeroflot deactivates brakes on nine aircraft, relies solely on reverse thrust

#211

Post by kelnos »

aunty_helen wrote: post #139
ssabev wrote: post #26

This is probably going to be just the tip of the iceberg. There was already articles around cannibalisation of planes so that you can service and repair an ever dwindling number of aircraft. If it keeps going on for another year or two it's not going to be good

This literally happens everyday, everywhere and to every airline. Sometimes even between airlines. I’ve personally been responsible for a part getting pulled off another engine from another airline and swapped for one that got its electrical connector damaged so the engine would ship on time. There is a whole industry of buyers and sellers of 2nd hand aircraft parts.

Sure, but those types of things are stopgap measures that work in a normal, unsanctioned market. Like, they need a part now, but there's none available in the maintenance hangar (or whatever), and it would take a few days to order one, so they ask another airline at the same airport to float/sell them the part. Once the ordered part arrives, they're back to their usual number of parts.

In this case, Aeroflot just cannot get more parts, period. The market for new parts is completely closed to them right now due to sanctions, and secondhand parts will only get them so far. We're talking about brakes here, which wear out to uselessness, so I doubt there's even much (if any) secondhand market for those. Once all the "Boeing brake pads" wear out and run out in Russia, that's it. They can't get new ones without someone violating sanctions. Well, unless they manage to bum spares from countries like China that aren't sanctioning them, or unless someone local can manufacture them to the correct specs.

Regardless, these other options get more and more expensive as time goes on.

Re: Aeroflot deactivates brakes on nine aircraft, relies solely on reverse thrust

#212

Post by inferiorhuman »

jrockway wrote: post #197
blibble wrote: post #69

Earlier quoted context omitted.

I'd agree if it was almost any other country meanwhile the Russian state has complete control of the media and 99% of the country's area is essentially empty

I feel like the planespotting community will eventually ask "hey what happened to that registration number ABC123" or "didn't Aeroflot used to have 80 777s, but only 79 have been seen in the last year"? I feel like it's hard to hide a plane that's designed for international travel in a highly regulated industry.

https://en.wikipedia.org/wiki/2003_Angola_Boeing_727_disappe...

Re: Aeroflot deactivates brakes on nine aircraft, relies solely on reverse thrust

#213

Post by sokoloff »

woodruffw wrote: post #79
striking wrote: post #66

Earlier quoted context omitted.

I believe this to be true (the article definitely states "Brakes are also necessary for aborting takeoffs", and V1 is the speed at which takeoff ~~occurs~~ edit: must be committed to), but this is only one instant of the journey. At other times it is certainly feasible to brake (landings included) with just the use of the thrust reversers.

> At other times it is certainly feasible to brake (landings included) with just the use of the thrust reversers. This could be true; it's also not particularly reassuring as a passenger :-) (Not doubting you specifically, but it'd be nice to have one of the many pilots on HN opine here. My understanding as a passenger is that commercial airliners use breaks because the margins are very narrow, especially in the pres…

There are two distances to calculate, called accelerate-stop and accelerate-go.

Accelerate-stop is the distance needed to accelerate to V1, lose an engine instants before that, take the first action to abort at V1, and the resulting accelerate-stop is the distance between the start and end of roll. On an uncontaminated runway, this is computed without thrust reversers. On a contaminated runway, you can compute it with thrust reverser on the assumed non-failed engine(s).

Accelerate-go is the distance needed to accelerate all engines to just below V1, lose and recognize the loss, continue to Vr, rotate, climb, accelerate to V2, and reach 35 feet above the ground at V2.

When the accelerate-stop and accelerate-go are the same for the chosen V1, we call that the balanced field length.

Brakes are critically needed to achieve anything close to the book accelerate-stop distance.

Re: Aeroflot deactivates brakes on nine aircraft, relies solely on reverse thrust

#214

Post by jrockway »

inferiorhuman wrote: post #212
jrockway wrote: post #197

Earlier quoted context omitted.

I feel like the planespotting community will eventually ask "hey what happened to that registration number ABC123" or "didn't Aeroflot used to have 80 777s, but only 79 have been seen in the last year"? I feel like it's hard to hide a plane that's designed for international travel in a highly regulated industry.

https://en.wikipedia.org/wiki/2003_Angola_Boeing_727_disappe...

We know it's missing, right? In the case the original commenter posted, they'd have to somehow prove it didn't crash.

Re: Aeroflot deactivates brakes on nine aircraft, relies solely on reverse thrust

#215

Post by fbdab103 »

userbinator wrote: post #127
sillywalk wrote: post #21

My heart bleeds. FTA: "Many parts in (western made) Russian passenger aircraft that would normally be easily replaced are rapidly wearing out with no replacement parts in sight due to the import of spare aircraft parts from Boeing and Airbus being banned since March 2022. " I wonder what other parts are wearing out.

I suspect they'll start making their own, if they haven't already been.

I am more surprised there is not a sufficiently rich black-market operation going around sanctions.

Random site[0] says,

>In general, airplane brakes can last between 1000-2000 landings before they are changed. An active airplane makes an estimate of two landings per day; this means the airplane needs to be changed after 18-36 months.

Even at multiple brake pads(?) per plane, that does not sound an insurmountable amount of shady dealings required to keep planes operational if you have 1.5 years of runway for your maintenance window.

[0]https://www.highskyflying.com/how-often-do-airplanes-change-...

Re: Aeroflot deactivates brakes on nine aircraft, relies solely on reverse thrust

#216

Post by Dalewyn »

WalterBright wrote: post #185
wkat4242 wrote: post #35

Earlier quoted context omitted.

It's not very responsive at all. Nor is it meant for this purpose. It's just a brake assist for use on the runway. Also, reverse trust is hard to maneuver with considering you will immediately start reversing once you've stopped moving. Unlike a brake that has a stop as an "end state". If they really start taxiing using that it'll lead to collisions at least, I'm sure, because of unintended reversing. It's a harebrai…

The thrust reversers are more than just an assist on the runway. You can land without the reversers, but I'm pretty sure you'll have to go get the brakes replaced before it's ready to fly again. It'll also consume a dangerous amount of the runway. The reversers are no joke, especially when the aircraft is heavily laden.

An aircraft operating nominally is designed and intended to be able to land safely relying on just the brakes. Thrust reversers are also used because they decelerate the aircraft quicker and with less wear on the brakes, aka thrust reversers are used out of convenience and benefits.

Thrust reversers may be used solely in an emergency that renders the brakes inoperable, but such situations are so exceptional they aren't useful for any general observations.

An aircraft that can't land safely with just brakes would not be certified to fly.

Re: Aeroflot deactivates brakes on nine aircraft, relies solely on reverse thrust

#217

Post by midoridensha »

moomoo11 wrote: post #173

I get that this isn't in USA but this is why I just zoom. Flying is such a unnecessary hassle, I don't really want to go somewhere dealing with airport shenanigans and nightmares. I'm not rich enough to fly private. Besides, flying has basically become like taking a public transit bus. It is unclean and passengers can be unruly (experienced an incident where person had to be arrested and removed from plane - drunk gu…

You sound like an American who's only flown domestic. Air travel isn't nearly that bad when you fly internationally, especially on the Asian airlines. Air travel in the US these days is a nightmare, but it's not like that everywhere.

Re: Aeroflot deactivates brakes on nine aircraft, relies solely on reverse thrust

#218

Post by sokoloff »

HeyLaughingBoy wrote: post #85
striking wrote: post #66

Earlier quoted context omitted.

I believe this to be true (the article definitely states "Brakes are also necessary for aborting takeoffs", and V1 is the speed at which takeoff ~~occurs~~ edit: must be committed to), but this is only one instant of the journey. At other times it is certainly feasible to brake (landings included) with just the use of the thrust reversers.

It's been a while, but isn't that V2? ISTR that V1 is the commit speed: above that point you have to take off since there isn't enough runway to abort.

V1 is the “takeoff decision speed” (roughly as you describe). Vr is the speed at which rotation occurs. Vmu is the “minimum unstick” speed (the lowest speed at which liftoff is possible). V2 is the takeoff safety speed, which is faster than liftoff speed, and the minimum target speed for initial climb.

Re: Aeroflot deactivates brakes on nine aircraft, relies solely on reverse thrust

#219

Post by Dalewyn »

flangola7 wrote: post #208
Dalewyn wrote: post #175

Earlier quoted context omitted.

I think the moral here is there is an unhealthy dash of sensationalism and propaganda that must be sifted away, if we actually want to take any worthwhile information out of this. As the saying goes, the first casualty in war is truth.

But there's no sensationalism or propaganda here.

There's a mile wide difference between "disabling some brakes according to manuals" and "disabling all brakes and relying on just the thrust reversers".

I know it's cool to harp that Russia is doomed, but propaganda is bad regardless whether it's coming from the Russians or the west.

Re: Aeroflot deactivates brakes on nine aircraft, relies solely on reverse thrust

#220

Post by ramses0 »

dylan604 wrote: post #209
nvy wrote: post #182

Earlier quoted context omitted.

So I used to work in aircraft maintenance (never in Russia though) and the policy is to change the brakes when there is $minimum_thickness of brake pad remaining. There's a little wire embedded in the pad and eventually as the pad wears thin the wire completes a circuit with the rotor, and lights up the aerospace version of the Check Engine Light. The brakes on these planes certainly have some remaining life but they…

>the aerospace version of the Check Engine Light. why does it use such a vague light. are they afraid one more specific light for "brake pad warning" lamp will just make the cockpit untenable?

Pilot can't go out and replace the brake pad on the tarmac. Technician busts out the ODB code-reader and says: "Huh, needs a new left brake pad"
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