Search found 2416 matches

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by jetmech
Sun Aug 21, 2022 4:10 am
Forum: Civil Aviation
Topic: Boeing 767: 40 years in airline service
Replies: 109
Views: 14567

Re: Boeing 767: 40 years in airline service

Happy 40th to the 767! I was fortunate enough to work on 767s powered by all three of the major engine manufacturers (762 P&W, 763 GE, 763 RR). I remember one of the 763 RR's had some experimental engine type fitted. Can't remember what it was specifically, but probably something to do with the ...

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by jetmech
Sun Aug 14, 2022 12:10 pm
Forum: Technical/Operations
Topic: Can steel brake pads be used in systems designed for carbon?
Replies: 13
Views: 2329

Re: Can steel brake pads be used in systems designed for carbon?

It is more than just the brakes and wheels. I cant remember if it was a LRU change or a software update for the anti-skid / autobrake. I'm sure there was a LRU change to the box that controls the anti skid. It make sense as the two types of brakes would most probably have different friction charact...

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by jetmech
Sat Aug 13, 2022 7:38 am
Forum: Technical/Operations
Topic: Can steel brake pads be used in systems designed for carbon?
Replies: 13
Views: 2329

Re: Can steel brake pads be used in systems designed for carbon?

Dalmd88 wrote:
We converted our 737 NG fleet to carbon.

What other changes needed to be made aside from the wheels and brakes themselves? Did you need to modify the ABS system for instance?

Regards, JetMech

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by jetmech
Sat Aug 06, 2022 7:57 am
Forum: Travel, Polls & Preferences
Topic: Question on boeing B777-300
Replies: 28
Views: 4003

Re: Question on boeing B777-300

My dears, I'm nervous and stressed to take a boeing 777-300 for an 11Hours flight ,I have a few questions and your answers will ease my mind. 8-) 1) On boeing 777-300 is there the TCAS device? 2) pilots can quickly switch controls in case of problems (as on A350) during takeoff 3) how many pitot tu...

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by jetmech
Sun Jul 03, 2022 10:48 pm
Forum: Civil Aviation
Topic: EK Incident at Brisbane: debris causes hole in wing join fairing
Replies: 42
Views: 10420

Re: EK Incident at Brisbane: debris causes hole in wing join fairing

Tire is damaged due to FOD (nose gear bolt?) on takeoff roll. Sounds plausible. Apparently, if it was FOD, it was not from the nose gear. A comment in the Avherald article states that the nose gear photo was actually taken in April 2017 at Dusseldorf. I also have it on good authority that there was...

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by jetmech
Sun Jul 03, 2022 10:36 pm
Forum: Civil Aviation
Topic: EK Incident at Brisbane: debris causes hole in wing join fairing
Replies: 42
Views: 10420

Re: EK Incident at Brisbane: debris causes hole in wing join fairing

Tire is damaged due to FOD (nose gear bolt?) on takeoff roll. Sounds plausible. Apparently, if it was FOD, it was not from the nose gear. A comment (now deleted??) in the Avherald article stated that the nose gear photo was actually taken in 2017 at Dusseldorf. I also have it on good authority that...

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by jetmech
Sun Jul 03, 2022 9:10 pm
Forum: Civil Aviation
Topic: EK Incident at Brisbane: debris causes hole in wing join fairing
Replies: 42
Views: 10420

Re: EK Incident at Brisbane: Hole in Fuselage

Yes, but I would have thought the real mystery would surely be how did the debris from the tyre bursting escape from the wheel well to cause the puncture. Am I incorrect in thinking the wheel well is enclosed? The punctured panel in question is the wall of the wheel well itself. As far as I underst...

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by jetmech
Sun Jul 03, 2022 11:47 am
Forum: Civil Aviation
Topic: EK Incident at Brisbane: debris causes hole in wing join fairing
Replies: 42
Views: 10420

Re: EK Incident at Brisbane: Hole in Fuselage

Surely the MLG and tyre would be fully stowed and enclosed long before the aircraft reached cruise height, would it not? Yep, that's apparently what happened. Landing gear was retracted with the tyre bursting 30-40 minutes after TO according to passengers on board. What the root cause of the tyre f...

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by jetmech
Sun Jul 03, 2022 8:05 am
Forum: Civil Aviation
Topic: EK Incident at Brisbane: debris causes hole in wing join fairing
Replies: 42
Views: 10420

Re: EK Incident at Brisbane: Hole in Fuselage

The flight crew would not have been able to see any hole at that position so what do you think could have alerted them? I guess they knew they had a tyre let go from the TPIS on ECAM. Probably had no idea about the hole in the fairing though. On that note, the report say that the damage was caused ...

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by jetmech
Thu Jun 16, 2022 1:03 pm
Forum: Technical/Operations
Topic: Decals and flags
Replies: 8
Views: 2730

Re: Decals and flags

The left side flag has the field of stars in the upper left corner and stripes facing aft on the aircraft. But, you can't use this decal on the right side, it is a different part number and has the field of stars in the upper right corner with the stripes facing aft.. This started a somewhat humoro...

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by jetmech
Thu Jun 16, 2022 12:53 pm
Forum: Technical/Operations
Topic: 737 spoiler mixer / ratio changer question.
Replies: 6
Views: 2331

Re: 737 spoiler mixer / ratio changer question.

Today i had possibility to check system behavoir on real aircraft, cables from mixer definitely move to both direction. Via quadrant they move valves inside actuator but spoiler remains in the same position, it is already at downstop. I think that valve inside actuator is fully open when spoliers a...

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by jetmech
Wed Jun 08, 2022 12:16 pm
Forum: Technical/Operations
Topic: Portable External Oil Cooler
Replies: 11
Views: 2733

Re: Portable External Oil Cooler

I think the key to this is understanding which aircraft use a hydraulic to fuel heat exchanger. I only just realised it was the case drain flow by itself that gets cooled. I always thought it was the entire return flow prior to the reservoir. If I am not mistaken, the AMM mentions to not operate th...

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by jetmech
Sun May 29, 2022 11:15 pm
Forum: Technical/Operations
Topic: Portable External Oil Cooler
Replies: 11
Views: 2733

Re: Portable External Oil Cooler

a) Is this oil cooler (PEOC) used a lot for airlines and MROs (maintenance, repair, and overhaul)? I've never personally seen such a device used. b) Is this oil cooler (PEOC) used only for 737 MAX or all Boeing aircraft? I presume such a device would be needed for all Boeings if you were running el...

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by jetmech
Sun May 29, 2022 7:51 pm
Forum: Technical/Operations
Topic: 737 spoiler mixer / ratio changer question.
Replies: 6
Views: 2331

Re: 737 spoiler mixer / ratio changer question.

As for maintenance manual, this weak signal may be a good diagnostic metric for some reason. For example, weak can become zero if there is any problem with flow or alignment... Definitely makes sense. No doubt it's a complex rigging / adjusting task when you change the mixer and / or ratio changer....

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by jetmech
Sun May 29, 2022 5:20 am
Forum: Technical/Operations
Topic: 737 spoiler mixer / ratio changer question.
Replies: 6
Views: 2331

Re: 737 spoiler mixer / ratio changer question.

Just speculating, but perhaps the changer doesn't care whether the spoilers are stowed by the speed-brake lever. It commands right spoiler drop for left wheel turn, in all cases. If the spoiler is stowed, then no impact. If not stowed, then the changer has the desired effect on the right spoiler. T...

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by jetmech
Sat May 28, 2022 2:01 am
Forum: Technical/Operations
Topic: 737 spoiler mixer / ratio changer question.
Replies: 6
Views: 2331

737 spoiler mixer / ratio changer question.

Hello All, I've been reading up on the 737 spoiler mixer / ratio changer mechanism. It's an amazingly complex and clever device which takes some studying to understand. The following picture is the mixer / ratio changer in the neutral control wheel, speed-brakes down configuration. https://lh3.googl...

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by jetmech
Sat May 28, 2022 12:37 am
Forum: Technical/Operations
Topic: Is an Aircraft Perfectly Balanced 50/50?
Replies: 17
Views: 2318

Re: Is an Aircraft Perfectly Balanced 50/50?

If you were to draw a line down the middle of the plane, would both sides be equal in weight? Probably not, but it'd be close to within a very small percentage of the overall OEW. As others have said, any lateral weight imbalance from airline specific cabin fitouts acts upon a very small moment arm...

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by jetmech
Tue May 17, 2022 5:45 am
Forum: Technical/Operations
Topic: Why does a 737-700 use flap 1 and not zero flap for take off?
Replies: 23
Views: 3641

Re: Why does a 737-700 use flap 1 and not zero flap for take off?

1. Lift means drag, longer takeoff roll etc. Sure, but you're going to have huge amounts of drag on takeoff in any case due to the extended landing gear and in many cases, partially extended trailing edge flaps. If anything, extended leading edge devices reduce the suction peak and thus may slightl...

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by jetmech
Mon May 16, 2022 5:20 pm
Forum: Technical/Operations
Topic: Why does a 737-700 use flap 1 and not zero flap for take off?
Replies: 23
Views: 3641

Re: Why does a 737-700 use flap 1 and not zero flap for take off?

How much of effect can be achieved with trailing edge devices only? Not sure to be honest. What I can say is the main-plane and trailing edge flaps operate much more effectively when interacting with attached flow. The role of leading edge devices is to promote attached flow by delaying or reducing...

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by jetmech
Mon May 16, 2022 11:38 am
Forum: Technical/Operations
Topic: Why does a 737-700 use flap 1 and not zero flap for take off?
Replies: 23
Views: 3641

Re: Why does a 737-700 use flap 1 and not zero flap for take off?

To increase the AoA margin, doesn't the slat have to be fully deployed to open the slot and thus provide increased AoA margin by accelerating the air through the slot, reenergizing the boundary layer? Slats increase the useable AOA in the sealed position. This is due to the increase in leading edge...

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by jetmech
Sun May 08, 2022 9:46 am
Forum: Technical/Operations
Topic: CFM Engine High Oil Consumption
Replies: 28
Views: 4199

Re: CFM Engine High Oil Consumption

Is there not also something about the turbine bearing seals not fully pressurizing at low RPM and thus aircraft that tend to have longer than normal taxiing can end up with higher oil consumption? In addition, at low engine RPM, air-oil separators are less effective as they rely on centrifugal forc...

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by jetmech
Thu May 05, 2022 9:11 am
Forum: Technical/Operations
Topic: CFM Engine High Oil Consumption
Replies: 28
Views: 4199

Re: CFM Engine High Oil Consumption

Golly, you should see PW engines, if you want to see oil consumption. Or an A35K / Trent XWB after a 15-16 hour sector :shock: ! I guess I'm not understanding how an entry of 0 pints added didn't raise any red flags. Or is it possible to service the oil without adding any. Yes, it is possible for n...

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by jetmech
Sat Dec 18, 2021 11:20 am
Forum: Technical/Operations
Topic: 737 MAX APU Inlet Door
Replies: 30
Views: 4427

Re: 737 MAX APU Inlet Door

Horstroad wrote:
spike sticking out of it (whatever it's called. I'm not familiar with the 737)

The colloquial name is "bicycle seat", the function of which I believe, is to act as a vortex generator to encourage air to go into the inlet if the APU is operated in flight.

Regards, JetMech

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by jetmech
Wed Dec 15, 2021 8:33 am
Forum: Technical/Operations
Topic: Can anyone identify the various noises on this video of a B737 horiz stab jackscrew in operation?
Replies: 3
Views: 901

Re: Can anyone identify the various noises on this video of a B737 horiz stab jackscrew in operation?

I am wondering whether Boeing and Airbus horizontal stabilizer jackscrew assemblies are vulnerable to malfunctions that would result in catastrophic losses of the entire aircraft? Modern Boeing and Airbus jack screws use the recirculating ball design with an unthreaded backup shaft mounted concentr...

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by jetmech
Wed Dec 15, 2021 8:14 am
Forum: Technical/Operations
Topic: Which airliners have two jackscrew assemblies to control their horizontal stabilizer?
Replies: 7
Views: 1686

Re: Which airliners have two jackscrew assemblies to control their horizontal stabilizer?

Or do any current models All the Boeing's (747, 767, 777) and Airbus (A330 / 340) I've worked on only have the single jackscrew. Pretty sure the 737, 757, 787, A320, A350 and A380 are similar. These are configured with an unthreaded backup shaft located concentrically inside the threaded shaft, and...

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by jetmech
Wed Dec 01, 2021 11:38 am
Forum: Technical/Operations
Topic: L1011 - High Angle of Attack on approach and landing
Replies: 15
Views: 3732

Re: L1011 - High Angle of Attack on approach and landing

DL_Mech wrote:
DLC allowed for the aircraft to maintain a constant pitch angle on approach while using spoilers to correct for glide path variations.

Did the tailplane have any involvement when DLC was in operation?

Regards, JetMech

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by jetmech
Thu Nov 25, 2021 10:44 pm
Forum: Technical/Operations
Topic: Can 747s really use flaps even with total hydraulic loss and if so why isnt this on other aircraft?
Replies: 19
Views: 4862

Re: Can 747s really use flaps even with total hydraulic loss and if so why isnt this on other aircraft?

seven47 wrote:
They take a long time to transit to the selected position!

We used to extend flaps in the hangar on alternate power for that exact reason.

Regards, JetMech

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by jetmech
Thu Nov 25, 2021 10:12 am
Forum: Technical/Operations
Topic: Can 747s really use flaps even with total hydraulic loss and if so why isnt this on other aircraft?
Replies: 19
Views: 4862

Re: Can 747s really use flaps even with total hydraulic loss and if so why isnt this on other aircraft?

With no hydraulics, you have no flight controls! Just to add to the topic in general, the 747 flaps are powered by two of the four hydraulic systems only, with #1 powering inboard flaps and #4 powering outboard flaps. Thus, any issues associated with alternate flap extension (i.e. extended transit ...

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by jetmech
Thu Nov 04, 2021 9:33 am
Forum: Technical/Operations
Topic: Is it dangerous when aircraft carry fuel in a center tank beneath the passenger cabin?
Replies: 43
Views: 4450

Re: Is it dangerous when aircraft carry fuel in a center tank beneath the passenger cabin?

Tristarsteve wrote:
But then it must be split between the centre and tail tank in the correct ratio.

5.2 : 1 IIRC?

Regards, JetMech

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by jetmech
Tue Aug 10, 2021 9:50 am
Forum: Civil Aviation
Topic: BA 787-8 Nosewheel collapse at LHR
Replies: 156
Views: 48994

Re: BA 787-8 Nosewheel collapse at LHR

DartHerald wrote:
You must be the leprechaun who maintains the Aer Lingus fleet!

LOL, 6' !

Regards, JetMech

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by jetmech
Tue Aug 10, 2021 9:47 am
Forum: Technical/Operations
Topic: Question For the Mechanics: Which Commercial Aircraft Have Been Easiest and Most Difficult For You to Work On?
Replies: 71
Views: 14775

Re: Question For the Mechanics: Which Commercial Aircraft Have Been Easiest and Most Difficult For You to Work On?

celestar345 wrote:
Sliding down the exhaust for the first time to remove panel for changing the ignitor plug... and forgot to keep my head down...

You hit your head on the cookie cutter?

Regards, JetMech

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by jetmech
Tue Aug 10, 2021 6:46 am
Forum: Civil Aviation
Topic: BA 787-8 Nosewheel collapse at LHR
Replies: 156
Views: 48994

Re: BA 787-8 Nosewheel collapse at LHR

I suspect that the wrong hole also serves a purpose which is why it's there in the first place. What is the reason for the second "wrong" hole? Most pivot pins are hollow for weight saving. A solid pin would not only be heavy but far stronger than required. So then, how high up is the pin...

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by jetmech
Sat Aug 07, 2021 2:46 am
Forum: Technical/Operations
Topic: Question For the Mechanics: Which Commercial Aircraft Have Been Easiest and Most Difficult For You to Work On?
Replies: 71
Views: 14775

Re: Question For the Mechanics: Which Commercial Aircraft Have Been Easiest and Most Difficult For You to Work On?

I've changed the BUG on a Trent 892 powered 777 and one on a GE90 powered 777. The RR by far was much easier, and quicker. I hear you! Just changing the BUG oil and filter on a GE90 is challenging enough, having to remove pipework and then trying to lockwire the drain plug. It certainly seems to be...

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by jetmech
Wed Aug 04, 2021 9:57 am
Forum: Technical/Operations
Topic: Vent on engine nacelle of the Boeing 737-200?
Replies: 3
Views: 1218

Re: Vent on engine nacelle of the Boeing 737-200?

Maybe a cooling air intake for the TR actuator?

Regards, JetMech

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by jetmech
Mon Mar 08, 2021 9:57 am
Forum: Technical/Operations
Topic: Comparing Boeing 787 and Airbus A350 wing design
Replies: 19
Views: 3395

Re: Few questions about the A310 (and A300)

Static height brings stiffness with the 4th exponent? For a simple cantilever beam of rectangular cross section acted upon by a point load at the free end, the deflection is given by PL^3 / 3EI; with P being the magnitude of the point load, L the length of the cantilever, E the Modulus of elasticit...

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by jetmech
Sat Mar 06, 2021 6:43 am
Forum: Technical/Operations
Topic: Qatar Airways threatens Pilots for taxiing with both engines
Replies: 46
Views: 10614

Re: Qatar Airways threatens Pilots for taxiing with both engines

I don't think the inboard will be moving backwards. We don't do pivot turns with a stopped main gear leg. True, if you look at the minimum turn radius diagram for the 35K (Fig 4-3-0-991-001-B01 https://www.airbus.com/aircraft/support-services/airport-operations-and-technical-data/aircraft-character...

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by jetmech
Fri Mar 05, 2021 10:56 am
Forum: Technical/Operations
Topic: Qatar Airways threatens Pilots for taxiing with both engines
Replies: 46
Views: 10614

Re: Qatar Airways threatens Pilots for taxiing with both engines

I've observed a number of single engine taxis by various airlines including Qatar. The most glaring problem is the final turn onto the parking bay. If this turn is sharp enough, the inboard engine will physically be moving backwards during the turn. Thus, if the single engine chosen for taxi happens...

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by jetmech
Sun Feb 28, 2021 12:30 am
Forum: Technical/Operations
Topic: Shortest runway airports with regular A380 service
Replies: 27
Views: 7345

Re: Shortest runway airports with regular A380 service

I thought A380 demanded at least 10,500 (at 70 percent load). We recently had 9V-SKQ leave ASP for SYD for a gear swing. She comfortably took off from the 7,999 ft runway and departed with 100 tonnes of fuel aboard due to flying gear down all the way to SYD. This would have put take off weight arou...

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by jetmech
Thu Sep 03, 2020 5:49 am
Forum: Technical/Operations
Topic: Over wing fueling the 747
Replies: 23
Views: 3319

Re: Over wing fueling the 747

Hilarious, really. I’ve seen planes where the overwing ports are actually below the pressure fueling lints, so overwing fueling shorts the potential fuel load. There were definitely overwing fueling ports on the classics, but they were well below the max level of the tank. Usually the overwing acce...

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by jetmech
Wed Jul 01, 2020 1:24 pm
Forum: Technical/Operations
Topic: An-225 pitch trim
Replies: 4
Views: 2407

Re: An-225 pitch trim

Looking at this picture, there seems to be three moveable sections on each side of the horizontal stab. Yes, it's an interesting elevator setup. The outboard sections look to be double or triple hinged. If I’m not mistaken both AN124 and AN225 use a fly by wire flight control system. That would cer...

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by jetmech
Mon Jun 29, 2020 1:28 am
Forum: Technical/Operations
Topic: An-225 pitch trim
Replies: 4
Views: 2407

An-225 pitch trim

Hello All, I'm curious as to how the An-225 achieves longitudinal pitch trim. As far as I can tell, the An-225 has a fixed horizontal stabiliser and hence, the elevators are the only way to provide pitch trim. https://cdn.cnn.com/cnnnext/dam/assets/180831153107-antonov-fedykovych-8.jpg Yet as per th...

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by jetmech
Mon Jun 22, 2020 11:03 am
Forum: Technical/Operations
Topic: A350-1000 fuel burn
Replies: 179
Views: 42025

Re: A350-1000 fuel burn

zeke wrote:
Not really 700 kg is a tad high, you could do that taxi in 10 minutes at the moment with the amount of traffic around at that time of day.

I see. Yes,10 minutes would pretty much cover it. Thanks for the info.

Regards, JetMech

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by jetmech
Mon Jun 22, 2020 8:43 am
Forum: Technical/Operations
Topic: A350-1000 fuel burn
Replies: 179
Views: 42025

Re: A350-1000 fuel burn

Starlionblue wrote:
Either way, for an A359 or A351 a few hundred kilos is most likely not going to have an impact unless your planned fuel is very tight.

Thanks for the info!

Regards, JetMech

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by jetmech
Mon Jun 22, 2020 8:30 am
Forum: Technical/Operations
Topic: A350-1000 fuel burn
Replies: 179
Views: 42025

Re: A350-1000 fuel burn

I can't recall an actual burn for that taxi, but the number seems pretty high. It's just a straight shot down Alpha. Unless you're going at rush hour and know you'll be doing a lot of holding on the way to the hold point. I see. The departure time is scheduled for 2155 but usually ends up being aro...

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by jetmech
Mon Jun 22, 2020 7:25 am
Forum: Technical/Operations
Topic: A350-1000 fuel burn
Replies: 179
Views: 42025

Re: A350-1000 fuel burn

Where do you need 700 kg taxi fuel ? The aircraft / airline in question almost always departs from bay 9 or 10 at Sydney International Terminal. If they are taking off to the north from 34L, they have to taxi almost the full length of 16R-34L. Would 700 kg be a typical fuel consumption for this dis...

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by jetmech
Mon Jun 22, 2020 2:33 am
Forum: Technical/Operations
Topic: A350-1000 fuel burn
Replies: 179
Views: 42025

Re: A350-1000 fuel burn

The way I read that would be an actual tow of approx 285t. That explains the low fuel burn compared to the usual 6.8t at higher weights. Yeah it makes much more sense now. I think we can assume the fuel burn range at 319t would be roughly 6.8 to 7 depending on temperature and everything. I managed ...

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by jetmech
Mon Jun 15, 2020 6:02 am
Forum: Technical/Operations
Topic: Could an airliner save fuel by being unstable
Replies: 22
Views: 3275

Re: Could an airliner save fuel by being unstable

With that, the question is what happens at critical AoA and what stalls first. For swept wing, wing root has to stall first. That creates nose down momentum and helps plane to avoid full stall - if that plane is not 737max. That also allows pushing flight envelope to maximal AoA, hence lower speed ...

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by jetmech
Mon Jun 15, 2020 4:42 am
Forum: Technical/Operations
Topic: Could an airliner save fuel by being unstable
Replies: 22
Views: 3275

Re: Could an airliner save fuel by being unstable

Similar, but not exactly an instability: As far as I understand, canards instead of tail mounted stabilizer could be a fuel saver I think this is an interesting idea. The wings of commercial types need to be bigger than that required to lift the mass of the aircraft due to the negative lift produce...

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by jetmech
Thu Jun 11, 2020 2:30 am
Forum: Technical/Operations
Topic: 747-400 elevator control system
Replies: 14
Views: 2742

Re: 747-400 elevator control system

Standarization of horizontal stabilizer production to -400 standard, with provisions for tail tank installation, requiring re-routing of hydraulic lines.. Thanks. Evidently, the presence of the additional equipment required for the HST precluded the crossing over of hydraulic lines. Regards, JetMech

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by jetmech
Tue Jun 09, 2020 2:00 pm
Forum: Technical/Operations
Topic: A350-1000 fuel burn
Replies: 179
Views: 42025

Re: A350-1000 fuel burn

WOW. So basically at 319t its close to an 18hr bird with a full house of 360 something pax. Wow. From memory it was only around 90 passengers going out but this was made up for with cargo. Colder temps at cruise? That could be part of it. I was thinking they had great tailwinds and took advantage o...

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