That's the one I missed most. I flew on one only two times and climbed around on one at the Mojave boneyard but what a stunning aircraft that was.

Dean, yes, I liked them better than the DC-10's. I think the last time I flew one was about 1996 for a one hour flight from Atlanta to Tampa.

Me too

Same here.I flew the L1011’s of Eastern ,TWA,and Delta.

They should bring back the L1011 as a twin jet with Rolls Royce Ultrafan.

Also greatly reduced the working area within the aft equipment bays for servicing other systems.

That isn't true.

Douglas built a work platform under #2 engine that made it easy to work under and service. Worked on plenty of MD11 and DC10.

The ll1011 came to the market too late and was too $$ . The DC-10’s crashes from the “pinto” door sealed their fate

A friend of mine started with the 727 as an F/E. For the -200, a first departure of the day meant opening the rear galley doors and looking into the No. 1 and No. 3 engines with a flashlight. The No. 2 engine never got as good of a look, being buried in the fuselage. Inspecting the engines on the 757, 767, and 737 is a lot easier

There's another factor...all these tri-jet configurations are prone to stalling. Insurers got a bit nervous about underwriting those airframes, so along with guzzling more jet fuel, higher insurance premiums.

@@selfdo rear mounted engine twin jets were just as bad at stalling

@@andrewsmart2949 Which is why they’re very uncommon in any new airliner now.

The Ford Tri motor was the first plane with Tri Engine with 3 Props.

@@Perich29 which made it more reliable as it could still fly reasonably well if one engine failed,and aircrafdt engines were not the most reliable back then LOL

Hey Georgia, You nailed it! The 60-minute rule died because newer engines performed better and for longer periods of time. Nothing more, and nothing less.

Interesting... I always assumed the three engines were for reliability in crossing the ocean. I never though about mountain ranges. Thanks Captain for that explanation.

@@minerran I agree, I too always assumed it was all about over water.

@@jameshayward8533 It was for any operations that required higher reliability. Over water is just one example.

Twin engine planes HAD demonstrated that they could fly over high mountains on 1 engine, but, like you said, the possibility that the remaining engine could fail made the FAA say "NO", although there were some exemptions. Still, it was illegal, until the FAA relaxed that rule.

LOL!

S tier reference!

so have ya ever seed a growed man necked? asking for Buba

Oh My!

my Dad says you don't hustle on defense

Wow you don’t say

Thanks, Dr. Obvious.

That’s what he said ⁉️🤪

Lindbergh did it with one engine

Hold on, jets can fly _over water?_ Witchcraft!

Yeah, exactly. Design bureaus of the Soviet union had a peculiar kind of freedom, being completely independent of commercial viability limitations, and could make weird stuff like a regional trijet with maximum seating around 30 (!!!)

Jet fuel almost identical to kerosene

@@acalabash yeah

​@@acalabash There was nothing weird - considering the very limited choice of engines. It was either three small AI-25 engines ("kerosene burners") or two large one (far, far worse). The end result was economically mediocre, but not outrageously expensive. Today, right now, the price of the few remaining domestic Yak-40 flights hovers between the prices of second-class and first-class sleeper trains (all these routes are competing with trains directly). That said, the four-abreast Yak-40 seating is a torture (even when the flight is less than an hour).

@ acalabash

@Alex Brown *Bad-dum-tass*

@@greateraviationgl91 W

"putum tish!" (rimshot)

omg 727 wysi funneh lmaooo being serious tho, I’ve seen that plane and, and also got to see the L1011, beautiful pieces of engineering

In my working life I lost count of the number of flights I took around Australia (as a passenger) on the B727, wonderful and fast aeroplane !

I agree, 100%! From birth, until age 22, I was a frequent air traveler. It was common to take 6-10 flights during summer vacations. My father worked for an airline based in Miami, Florida. We had family scattered around the country. My earliest memories are of the Lockheed Electra, and I still have a special place in my heart for the plane. In the 60's the 727 joined the lineup and the Electra flights only flew to one of our regular destinations. The Electras were completely retired by the mid 70's. From then on it was all 727's, with the occasional DC-9. For the odd international trips, it was the 10-11. In my eyes, it was an especially beautiful airplane. The first time I rode on one, I had the opportunity to follow along behind the first officer as he did the "walk around" inspection. I was in awe at the size of everything. The engines were huge, the wheels were huge, the wings were huge. I had a hard time believing that something that big could actually get off the ground. Then once we boarded, I was again impressed by the size. It was a very comfortable plane to ride on, and the sound was different from anything else I'd flown on. I only got to fly on the 10-11 maybe a dozen times. Maybe that's why it remains such a special memory. Thanks for the walk down memory lane.

Bit like cars, eh?

Ah yes, brings back memories of going in our backyard when growing up and watching all the different types of planes on final to OAK. Now when I go to my parents and see planes, all the commercial airplanes are 737’s with the occasional Embrear. Also not much variety with the cargo haulers.

Yea, but the 787 is beautiful

It’s the same for the once great American auto industry all down the toilet. What a shame.

Agreed, its the reason why I'm an avgeek today. I took my first international holiday some time in the 90s, i think i was 6 years old at time and i remember the terminals at Tokyo Narita airport were filled 747s, DC-10s, and the occasional A340. Even the color schemes were more attractive. I could distinguish the 747 variants at that age as we flew with JAL and they had the -200, -300, and -400 at the time and got a chance to fly on all of them. Missed out on a Trijet unfortunately. I think the last era of interesting jets was around 2008. I flew to HKG and the 747s were still used by the European airlines at the time

The engines on the L-1011 and DC-10 WERE high bypass turbo fans - just not *AS* high a bypass ratio as current engines. You seem to be thinking of the engines on the 727 and the EARLY models of the 737.

I flew to Qatar once from MD in a DC-10. In talking with the crew I learned they flew the whole way on just the two wing mounted engines. 😐

S C - Yuh!! It was AMR 191 on 5-25-79 that had engine #1 develop a miss at O'Hare. Tickets were in-hand, but got PO'd when found new Mom-in-Law skimming us over Wedding Reception Hall, forcing us from SAT to a FRI, all for huge kickback. Arranged & self-pd for all including little sht like chapel, preacher, license, hall, invitations, flowers, catered food, liquor, bartender, photographer, 7pc band, limo, etc all myself to get orig date of SAT 5-12. On 5-25 At LAX, on way back to G.R. MI from Hawaii, picked up LA Times Xtra Editn w/news DC-10 for original tickets, had augured it in on flight from O'Hare to Trailer Park. Wife's Mom hated me for rest of Mom's life ending 1997, as if not for me & my detective, she would have had her really huge payout that had always dreamed of from AMR on loss of her daughter, "she loved so very much"! She also didn't get that huge kickback she was counting on either!! Too Bad...So Sad!!! As the ole farmer said, some days ya steps in it, some days ya don't!!! Sincere RIP for "lucky couple" (United on strike) that had scooped up our original tickets, taking our places...

Besides American Flight 121 at O'Hare, there was also United Flight 232 at Sioux City, IA, when the #2 engine on a DC-10 blew up and destroyed all 3 nearby "redundant" hydraulic systems.

@@erwinschmidt7265 Sorry, I'm bit confused about the dates and where you were going to/from. Your original wedding date was Sat 5-12-79 but your M-I-L-to-be tried moving it to Fri 5-11-79; and if you'd got married on the Friday, then you would've been on AA191 (Chicago to LAX) Fri 5-25-79 ... but instead were flying LAX to Grand Rapids that day because you got married on Sat 5-12-79? As you say, RIP to the unfortunate people who thought they were lucky getting your original seats on AA191 on Fri 5-25-79. :(

The first time I disembarked a 727 via the airstair was a strange but wonderful feeling

Flew on a nearly empty 727 from Chicago back to Indianapolis one time. Pilot came on intercom, obviously aggravated by many delays, said he was going to get us home as fast as he could. Out of all the jet takeoffs I had been through, maybe a couple dozen, I got pinned back in the seat so much I remember it today. The trip from Chicago to Indy is just blast off to cruising altitude and then level off and almost immediately coast back down, hardly time for beverage service.

She's my favorite airliner for this exact reason. Such a good looking plane!

@@mikekokomomike Most of the Crap7s fly at .75-.80M. We used to fly the 727 at .88 all the time. We had two versions, one had a higher Vmo. There was a mode A/B switch on the Airspeed indicator and if your Zero Fuel Weight was 'X' or below you could run in 'fast' mode (A). Not sure if I have that exactly right, but you get the idea. 250 knots to 10K. Then hold level flight till the IAS needle married right up tight to the VMO needle. Get one or two overspeed "Clicks" for style points and then pitch up to hold that speed to cruise. At this point, you're not going uphill too fast but downrange like an SOB! At cruise alt, just level off and let it rip. When it stopped accelerating (or you felt it buffet), match up the fans and call back and ask for coffee. During short flights, cruising at low ALTs it was nothing to see 385-400 indicated.

@@lbowsk Yeah, that was back when kero was $.12 a gallon & lowest block speed was all that mattered. Different world today.

...and I LOVED the roar it made.

Aye. The lack of a civil airliner to "pay the rent" also ensured the demise of AVRO Canada's other and most well known project; the AVRO Arrow.

@@jimtaylor294 Of course, Avro would have thrived if the Arrow hadn't been cancelled in 1959. The Jetliner program, which had been revolutionary when it first flew in 1949, was well and truly dead by the time that the Arrow program was in full flight, so to speak. The one flying prototype of the Jetliner had been stored intact until about 1955, when the nose section was cut off for eventual museum display, and the rest of it sadly scrapped.

@@daviddunsmore103 the arrow was beautiful, but I don’t think it would’ve made a difference in saving the industry

I flew a Lockheed L1011 once, I it was from Atlanta to California, and the L1011 was the most comfortable and quiet aircraft I'ver ever been in.

There are a few static displays in museums. Delta has one in Atlanta.

I have always felt the same way about the L1011. Something about it just gives of a sense of "elegance"... the were even called the "limousine of the sky"....

One of them even killed a Concorde, if I remember. An impressive feat.

DC10s Too bad about the L1011 was awesome but practically bankrupt Lockheed.

@Arthur Humphreys Bogus! MD 10 fallen apart caused the tire to explode. You're assertion of cheap tyres is bizarre as you'd find out next to time you opt not to swerve around some pallet wrap on the highway.

@Arthur Humphreys not cheap tires lol. It ran over a sharp piece of aluminum that was 2 feet long and a couple inches wide. The concorde weighs nearly half a million pounds.

@Arthur Humphreys The Concorde never had cheap anything ,even the passengers were worth a few Bob they had to be .

Agreed. That was a very unique, special aircraft loved by passengers, crew and pilots equally. I think only the A380 matches it in terms of having a very unique interior space but the A380 looks like a flying cow compared to the beauty of the L1011

Ditto! Loved flying in this tri-jet from Florida to Toronto back in the day. Spacious, well-appointed, and comfortable, the L1011 took flying to a new level.

@@stonerabbit344 Yep did the Toronto-Tampa a couple of times and Toronto-Vancouver. Thing is, I hate to fly but something about the L1011 made flying an enjoyable experience.

My dad worked for Delta back in the day, and as a boy I sometimes got to ride first class in a Tristar. Great airplane. And I agree about the A380's hideousness. Funny thing about that is how Boeing basically played Airbus to get them to blow money on that project, and the resulting airplane is not only commercially dubious, it also has a face like a blowpig compared to the beauty of the 747.

@@RCAvhstape The A380 is fugly! From the front at the gate, it looks like a constipated Beluga Whale with hydrocephalus.... the biggest government-subsidized commercial failure in aviation history. ...but it IS a comfortable plane: very smoothe and quiet.

Absolute rocketships...

@@Kilo-ct8dh Must not have been Aerosucre :P

@@phishbill I always considered the MD-80 a rocketship compared to the 727 - 100 and -200.

The tiny A319 is like an angry MINI Cooper taking off at the stoplight. It may be small but this only makes it easier for the pilots to get off the ground! Try flying on one out of a tiny municipal airport like Orange County-John Wayne Airport. The pilots lined up with the runway and kept backing up. I was wondering what the freak they were doing. They held the brakes and hit the throttle. The engines were LOUD for a tiny plane. Then they let go and it bolted down the runway like a top fuel dragster. They took off literally 6 or 7 seconds later and pulled a HARD left towards Denver. I was terrified because I didn't know the A319 was THAT agile. It rolled around like a damn F16! That was the only time I flew the A319. Would love to try it again some day.

Yup, killed the 4 engine jet as well

@@robertmcnearny9222 Quick note, Lufthansa is reactivating some A380's, according to Aviation Week.

@@bertg.6056 Gotta pay for them somehow.

@@robertmcnearny9222 The pilots shortage and fuel prices is also giving airlines pause over extending smaller capacity high frequency point to point routes.

Until two die

My favourite tri-jet airliner is the Boeing 727, the original!, it's actually my second favourite plane after the Harrier.

Surely the Junkers JU 52 and Ford Tri Motor are better known examples of 3 engine piston aircraft

@@mortimersnerd8044 Indeed, which in fact makes OPs mention even better. I did remember the Ford Tri Motor but this one with a tail 3rd piston engine is far more interesting in it's weirdness.

Britten what? Never heard of it. I thought you were going to say the ju 52/3m or the Fokker something something or even the Ford triplane. Need to check that one up

@@TheAllMightyGodofCod The Britten-Norman Islander has been a popular twin engine prop plane for decades, serving as a short haul airliner, business carrier, utility plane, and even as a 3rd world armed military plane as the Defender. The Trislander is a stretched fuselage version with a 3rd engine and prop stuck in the middle of the tail fin, DC-10 style. I believe it is still in use on a few out-of-the-way domestic routes due to its short-field capability.

Dallas to Ft. Lauderdale. Almost empty plane. Great Plane

"City bus" Lol, that's exactly right though.

@@jimmartin7881 My brother is an airline pilot, for a long time bus drivers had higher wages than pilot with 40 passengers

@@flashgordon3715 That's a disgusting reality, I remember in the late 90s I heard the salary of 2 pilots that flew for a cargo service that had died in a crash and I couldn't believe a pilot would work for it.

@@jimmartin7881 It's about experience. When starting out, the pay isn't mind blowing for the night hours, time away form home etc., however once you have a decade or two of experience, you may well be able to land a position with a major company and your salary will easily quadruple from the early days. Not sure why it's disgusting. If you don't like flying, you are free to work doing something else. Personally, I don't feel like being a pilot is a lot of work at all, as the vast majority of the time they simply sit around monitoring devices. The reason they are paid a good salary is that they have a lot of responsibility, in terms of the plane, cargo and passengers, as well as a lengthy and rather costly schooling phase.

Indeed true!

More importantly ETOPS only came into play due to engine technology and reliability

I think airlines moving from point to point service(instead of the old hub/spoke) on international flights has killed the giant 747 and Airbus A380 more than anything. They aren't as efficient as twin jets and airlines had a hard time filling them except on the really busy routes. Figured out their customers love that point to point convenience with no transfer/layover, they can charge more for that privilege, all the while operating smaller/more efficient planes.

@@AaronSmith-kr5yf Right, and that's why the Airbus A321XLR is selling well, and Boeing has nothing to oppose to it...

@@AaronSmith-kr5yf Actually to hub to spoke model for international long haul travel hasn’t changed much other than markets that can be profitably served from the hub. The vast majority of the traffic still flows from the carriers hub or hubs. Any of the major international carriers flow the traffic over their hubs. All big 3 US, SQ, LH, BA, KE, JL, EK, QR, AF/KL, etc still rely on their hubs. What has changed is more markets are viable from the hubs with smaller aircraft that have the range and efficiency. Previously it was only the jumbos that had the range to fly many routes

No, it's about the advances in technology and efficiency. In today's world the twins can do the job of the quads using far less fuel and without having to maintain an additional two engines. I was convinced this was a dangerous policy until I had a veteran Delta pilot explain it to me. As much as I hate it being a fan of large four engine aircraft, it really does make sense. I mean, sure, in a perfect world it would be technically better to have more engines, but it just doesn't make financial sense to do so. The fact that practically all passenger air travel today is accomplished with twins, and has been for years, and done so safely is the proof it works.

I've flown commercially on 707s, DC-10s, 737s, and Twin Otters. Flown military on P-3s, C-130s, C-141s, and DC-9s. Flown recreationally on parasails 😆, and a replica Ford Trimotor. My first flight was on a 707. I was 7 years old and flying alone LA to Montana. When I was 11 I flew alone to Boston. Things were a little different back then; they would let kids fly alone (expecting an adult would be there to pick them up, of course).

@@mikearmstrong8483 I go back far enough to have flown commercial on the 707 (once, Indianapolis to San Diego for Boot Camp), DC-3 (short round trip once, Atlanta to Ft. Meyers as a teen), 727 a few times, and a L-1011 once (Dallas/Ft. Worth to Indianapolis). Militarily on the C-3 and C-130 (MAC), and something small I don't remember for sure (perhaps C-141, also a MAC flight).

One European airline is taking some of their's out of the mothballs.

@@michaelbenardo5695 Yes, that would be Lufthansa.

Not a fan of the design of the a380

They put on a great show at Farnborough in 2016 too, seeing 727s and A380s being thrown around the sky like military jets is one of the most awesome sights to see. Shame that Farnborough has lost its airshow element, was a summer highlight for many including myself.

@@andrewwenzel3600 I went on board the 727 at Farnborough, which almost made up for never having flown in one (though I have flown in Tridents and a Tristar). I've always thought the 727 was one of the best looking airliners ever made.

@@paulshepherd8295 I have zero nostalgia for the 727, which I rode on many times during the 80’s and 90’s. The cabin noise level was crazy high due to the proximity of the engines to the fuselage. Add to that the low interior air quality (even after smoking was banned), a five hour flight was really draining.

@@wyganter Yes, I flew on BAC 1-11s a number of times. Not too bad unless you're sat near the back, next to those noisy Spey engines.

@@paulshepherd8295 There was hushkitted version as well

Did they let you steer a little?

I flew on a DC-10 LAX-DEN back in the late '70's, it even had a small stand-up bar amidships. Cool.

Yes.... I always felt reassured looking out the window of a Tristar in mid flight and seeing the RR on the engine. 😊

I flew in a Tristar as a kid - absolutely loved it

the best 4....3 engined aeroplane ever created. reliability of the large radials was not the same as the turboprop.

Plan to Buy a 7X, 25M after Major. Which is Better this or any 2 Engine for maintenance?

And a pretty fast hot rod back in the day, too! Tell me that wasn't fun!

I understand that the 727 was as close to a "flying tank" as an airliner could be.

My first jet engine flight was in 1970 in a 727, and when the pilot gunned it...I couldn't believe the acceleration. What a hoot.

I flew the 727 ten years.. Looking back on it.. It was crap.. Had Dutch roll problems,, same as 707 but tried to fix with dual rddders and yaw dampers.. It was noisy,, and 4 crashes in the first couple of months when it came out. As a pilot.. You learned how to operate within the strange flight characteristics it had instead of you flying the jet.. It flew you. Landing gear in the - 200. Bad location. You could mess up a takeoff without a pitch to 10% then later to 15. Like I said.. It needed special flight techniques

@@cjswa6473Would the Dutch roll issue be due to the engines being so close together being near the tail and also close to the center line of the aircraft? Or was is more of an aerodynamic flaw?

His exit mode was quickly fixed.

I think DB Ccooper was some grisly bear's lunch!

Not that much longer... They will start to get replaced by converted A330s and A320s in the coming years, possibly even some 777 conversions...

Some FedEx DC-10s are nearly 50 years old! ( To be retired in 2023 ). I'm sure the MD-11s will fly just as long.

Sadly, it was so influenced by BEA in requirement to suit that Nationalised Airline that other purchasers were put off. Hence conversation overheard on boarding one at Tel Aviv (BA substitute for Tri Star on the day), American voice "What the f... is a Trident and who flies them?" Reply "BA and the Chinese." Response unrepeatable. It was rumoured that a United States delegation invited by De Haviland to inspect DH's design offices and factory at Hatfield around 1960 to promote sales of the plane, were proudly shown the designs by a Government Minister, the 727 design project started a few months later.

Especially when it crashed

I flew on a few DC 10's and absolutely hated them.

The DC-10 was the poor man's Tristar.

@ Stuart Lee Lol... no, it was the smart man’s Tristar. You could buy a 747 for not much more than a Tristar or buy a DC-10 for a lot less. Lockheed was too used to cost-plus-fee military contracts where they basically have a blank check from the customer. That’s why they’d lose billions on the project. And the Tristar was a benefactor of luck. No DC-10 ever lost control of its horizontal stabilizer because it used a conventional jackscrew like every plane from a 747 to a Piper Cub. Just grease it with the right grease and make sure there isn’t a system that automatically drives it down and it’s fine. Only pure luck prevented that plane from being a smoking hole in the ground. Same with when an L-1011 had its centre engine explode. Shrapnel hit the fourth hydraulic system too but only luck prevented it from leaking. If it wasn’t a risk, they wouldn’t have installed hydraulic fuses in it like they did in the DC-10 and a lot of other planes as well after Sioux City. And Lockheed would get its lesson in cargo door explosions when a C-5 rear door blew out in 1975. It had learned its lessons about engines falling off on the Electra (design flaw, not incorrect maintenance) though all Lockheed wings are chronically weak.. like those of the Electra, the T-33, the Hercules, and others. The L-1011 entered service after the DC-10, exited service before the DC-10 (the only L-1011 still flying is the flying observatory.. while dozens of DC-10s still fly cargo every day), had a fraction of the number made, and flew a smaller number of hours due to chronically poor dispatch reliability. Hey... the TU-114 Rossiya has a better safety record than the L-1011. Must be a better plane, right? That’s the trouble with disparate sample sizes when comparing relative merits.

Yeah and the dc-10s were really quiet, especially when the engines would fall off their mounts. Quiet and smooth. It's just that sudden stop at the end that kind of jars you a bit.

I believe that the small engine you referring to was called the APU (Auxiliary Power Unit) and was there specifically to supply Auxiliary electric and hydraulic power for light and air conditioning and steering while the plane was on the ground and not at the ramp, the big engines could be shut down for fuel-efficiency and the passengers could still be kept comfortable and hydraulic controls would still function as they were meant to.

@@davidschwartz5127 No, it's definitely not just an APU. It's there to provide thrust at take-off. As per wikipedia: " Instead of attempting to replace the three engines with a completely different type, which would have been difficult with one engine buried in the tail, Hawker Siddeley's engineers decided to add a fourth engine in the tail, the tiny Rolls-Royce RB162 turbojet, fed from its own intake behind a pair of movable doors. The engine added 15% more thrust for takeoff, while adding only 5% more weight, and it would only be used when needed. BEA accepted this design as the

... as the Trident 3B

@@hoagy_ytfc I'll have to go that a look at the video again, I hadn't noticed it the first time thur.

The Trident 3B was a high-capacity short-medium range version of the 2E with a 16 ft 5 in (5.00 m) stretch and one additional RB.162 booster engine in the tail; 26 were built. The Trident Super 3B had an extended range of 692 km (430 miles). Two were built for CAAC China Airlines and were the last to be delivered in 1975 from Hawker Siddeley Aviation, Hatfield where I worked as an aircraft engineer and inspector.

Yes, noise was the factor that killed many early passenger jets, in addition to fuel consumption.

Nowhere near as noisy (or as polluting) as the 707s!

I had a flight SFO-ORD when I returned from a tour of duty that took me to 'Nam. The bird was practically empty.

It wasn't so quiet if you were in the back near the engines!

@@katazack Point taken! Guess I should have walked to the back of the plane during the flight to see what it was like.

Yup the trident was designed for exactly what BEA wanted, this limiting it for others sales. BOAC pulled the same stunt with VC 10 and reduced their order saying it was costly to operate, which it was due to its specialist design and performance for exactly what BOAC needed for high altitude hot weather short take off airports. At the time it was Boeing only aircraft company joke.

Good morning ⛅️

Good afternoon

Top o' mornin' to ya too

Fit like?

Yeah, for sure, m8

their...... y el b. 727 ...???? fantastico !!

I did wonder about that part of the video, it would've been the first time I heard of the Soviets giving any regard to safety

Really? I would think that a bus ride through Albania on a rickety, overcrowded bus would be quite the entertaining and educational experience. OK not really

And even then, there are a whole load of A330 and 777's kicking about that could be turned into cargo airframes, like Cathay Pacific is now doing

Actually you couldn't. The thing that gives modern jet engines efficiency in the largest part is a bypass ratio of 10:1 or greater. The trijets were designed back when "high bypass" meant a ratio of only 2:1. In short, the higher bypass ratios that are needed for efficiency can't be mounted on the aft fuselage. Drag makes it a losing battle.

@@StringerNews1 It isn't just that, it's also the fact you're talking about maintaining three engines instead of two. So yes, you probably could build a efficient tri-jet but why bother, when two engines can do the job just as well? Every time I asked a commercial pilot this question, I always got the same two fold answer: Today's twins have become technologically advanced to the point additional engines are unnecessary (at least for passenger travel), and more engines = more maintenance.

@@58HUSTLER you're correct, but the OP didn't say anything about operating costs, only fuel efficiency. Yes, three engines would cost more to maintain, but when it comes to fuel efficiency, it's all about fan size. You won't see an airliner like the B727 (or DC) again because those big fans are too big to be mounted anywhere but under-wing. Can't have three engines like that.

There would be on need to make a tri jet anymore. 2 can handle it and much more efficient in engines and also aerodynamics

No one cared about that when a #2 engine inside the tail or in the vertical stabilizer exploded, cutting control cables and pipes.

Being reliable and safe reduces the amount maintenance needed and increases lifespan: Attitudes that are considered typical for russian technology.

Then again, the Soviet airliners usually needed to reliably take of dirt runways

The A340 is a boring plane imo. It's just an A330 with 2 more engines. The tri jets and 747 tho are interesting planes

@@rv7w602 The trouble is you only have two major airliner manufacturers now. Once Trident went under the pressure was off the remaining two big names of Boeing and Airbus.