Search found 640 matches

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by Horstroad
Fri May 13, 2022 4:01 pm
Forum: Technical/Operations
Topic: Dirty airplanes
Replies: 6
Views: 1642

Re: Dirty airplanes

EK and Qatar stand out as premium airlines because of how clean their planes are. You’d be hard pressed to see a dirt mark from the jetway. They have the advantage of living in the desert. Dry dirt doesn't stick. Wet dirt does. Look at photos of aircraft stored at VCV that have been there for many ...

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by Horstroad
Tue Mar 22, 2022 12:10 pm
Forum: Technical/Operations
Topic: Flaps working slower ??? (airbus)
Replies: 12
Views: 2101

Re: Flaps working slower ??? (airbus)

I think we have to clarify the existing conditions first. Did we lose the entire green system, meaning no pressure at all? Then it's half speed. Single System Operation The loss of the hydraulic pressure to one of the two motors causes the power off brake to apply and hold the motor output shaft. Th...

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by Horstroad
Tue Mar 22, 2022 12:01 pm
Forum: Technical/Operations
Topic: A320 pushes nose down in flare mode
Replies: 12
Views: 3152

Re: A320 pushes nose down in flare mode

I can't answer for Boeing, but on Airbus pitch control in Normal Law is loading proportional to stick deflection. Regardless of speed, if you pull back a certain distance on the stick, you get a certain g loading. My understanding, which may be flawed, is that this would not work in the flare. As y...

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by Horstroad
Tue Mar 22, 2022 6:06 am
Forum: Technical/Operations
Topic: A320 pushes nose down in flare mode
Replies: 12
Views: 3152

Re: A320 pushes nose down in flare mode

It isn’t a reminder to flare. It’s done to simulate the back pressure that’s held during the flare of a conventional aircraft, as that’s far more intuitive to pilots. The 787 and 777-9 have a similar feature that basically does the same thing. The classic 777 does it as well, I just checked. The bo...

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by Horstroad
Mon Mar 21, 2022 8:03 pm
Forum: Technical/Operations
Topic: Flaps working slower ??? (airbus)
Replies: 12
Views: 2101

Re: Flaps working slower ??? (airbus)

@Horstroad: The fluid flow will increase because the one HYD pump has to pressurize Two HYD systems. The yellow system, as in normal ops, and the green system via the PTU. Thats why we have the PTU. With the PTU pressurizing the green hydraulic system the flaps would extend/retract at the normal sp...

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by Horstroad
Mon Mar 21, 2022 8:00 pm
Forum: Technical/Operations
Topic: A320 pushes nose down in flare mode
Replies: 12
Views: 3152

Re: A320 pushes nose down in flare mode

If a pilot doesn't do anything it would end up on the NLG. I've never seen it go down to -2, but then again, I've always applied back pressure as that is what is taught from your first flight in a single engine piston DA-20/C152/C172. I don't think any pilot would intentionally let the plane put it...

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by Horstroad
Mon Mar 21, 2022 4:59 pm
Forum: Technical/Operations
Topic: A320 pushes nose down in flare mode
Replies: 12
Views: 3152

A320 pushes nose down in flare mode

According to the FCOM and other documentation the A320 family aircraft push the nose down automatically when the flight control system goes into flare mode: The system memorizes the aircraft's attitude at 50 ft, and it becomes the initial reference for pitch attitude control. As the aircraft descend...

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by Horstroad
Mon Mar 21, 2022 3:03 pm
Forum: Technical/Operations
Topic: Flaps working slower ??? (airbus)
Replies: 12
Views: 2101

Re: Flaps working slower ??? (airbus)

The flow in through the hydraulic motors is the same. The same amount of turns is required to extend or retract the flaps a set distance no matter how many motors drive them. Why should the fluid flow increase? However as Spock540 pointed out the load for the motor would change. Both green and yello...

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by Horstroad
Sun Mar 06, 2022 10:39 am
Forum: Technical/Operations
Topic: Question about quotation on MD-11 landing speeds.
Replies: 7
Views: 2190

Re: Question about quotation on MD-11 landing speeds.

The horizontal stabilizer and elevators are about 30% smaller compared to the DC-10. That's why you need more speed to keep a certain level of control authority. Fun fact: When approaching FRA, ATC would often ask for todays mini-clean speed, the minumum speed in clean config (flaps and slats up), t...

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by Horstroad
Sun Feb 20, 2022 8:11 am
Forum: Technical/Operations
Topic: Unusual GSE
Replies: 1
Views: 1432

Re: Unusual GSE

Here's the video thumbnail:

Image


I assume it's for bags of used bed linen, blankets, pillows and stuff like that. Trash is usually collected by the caterer.

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by Horstroad
Mon Feb 14, 2022 8:04 pm
Forum: Technical/Operations
Topic: Fly-by-wire project help
Replies: 18
Views: 2111

Re: Fly-by-wire project help

Basic CRM teaches that only one pilot should be in control at a time. The takeover buttons assist with this. If the sticks were moving, they would not directly indicate surface position. The instruments indicate aircraft attitude and attitude trend. If you can't read the PFD, I don't think seeing a...

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by Horstroad
Sat Feb 12, 2022 1:31 pm
Forum: Technical/Operations
Topic: Do any jetliners sometimes require packs-off approaches?
Replies: 9
Views: 2537

Re: Do any jetliners sometimes require packs-off approaches?

The MD-11 does that. When the aircraft is between 4k and 1k feet and the engines are in T/O thrust mode or when the aircraft is below 1k feet and in air mode the PACKs will be switched off automatically. Additionally when both wing anti ice and tail anti ice are not switched on pneumatics are switch...

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by Horstroad
Wed Feb 09, 2022 12:14 pm
Forum: Technical/Operations
Topic: Tire Pressure on A32X Family
Replies: 9
Views: 2511

Re: Tire Pressure on A32X Family

But what difference would it make if we keep the same pressure for Nose wheel on longer jets. Won't it ensure fleet commonality? Under- or overinflated tires wear unevenly. While an underinflated tire is much worse than an overinflated tire you don't want either. An overinflated tire has less conta...

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by Horstroad
Tue Feb 08, 2022 2:43 pm
Forum: Technical/Operations
Topic: Fly-by-wire project help
Replies: 18
Views: 2111

Re: Fly-by-wire project help

The system design of the side stick did. The two side sticks are not connected and there is no feedback from the control surfaces. The B777 does both even though it's full FBW as well. I could probably list half a dozen recentish accidents of aircraft with fully connected controls still managed to ...

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by Horstroad
Tue Feb 08, 2022 11:11 am
Forum: Technical/Operations
Topic: Fly-by-wire project help
Replies: 18
Views: 2111

Re: Fly-by-wire project help

FBW has caused problems, like contributing to AF447 IMHO FBW on its own did not contribute to AF447. The system design of the side stick did. The two side sticks are not connected and there is no feedback from the control surfaces. The B777 does both even though it's full FBW as well. I don't want ...

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by Horstroad
Wed Feb 02, 2022 2:58 pm
Forum: Technical/Operations
Topic: Engine Start Procedure. Which one first?
Replies: 48
Views: 4672

Re: Engine Start Procedure. Which one first?

The start sequence on the MD-11 is 3 - 1 - 2. The APU is rubbish. Engine start has to be performed with packs off. Once eng #3 is running the pneumatic system #3 can be isolated and pack #3 be operated again. Same for system #1. System handling (packs off/on, isolating the systems, APU shut down, et...

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by Horstroad
Wed Jan 26, 2022 8:47 pm
Forum: Technical/Operations
Topic: Avionics Bay Access and Pressurization
Replies: 63
Views: 5524

Re: Avionics Bay Access and Pressurization

I would think the crew would want access to the E&E in the event of a fire. To let air into the fire and smoke into the cockpit? Not sure how smart that is.... The equipment down there is ventilated anyways. It's not sealed off. Usually you can throw stuff down to the E&E compartment fwd of...

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by Horstroad
Mon Jan 10, 2022 4:08 pm
Forum: Technical/Operations
Topic: DC-10 tail mounted engine angle
Replies: 9
Views: 2698

Re: DC-10 tail mounted engine angle

The inlet duct has indeed an angle of about 2° to follow the shape of the fuselage. The engine itself however is mounted horizontally level. edit: As you can see here there is a 2.5° angle between the inlet duct centerline and horizontal and again a 2.5° angle between the inlet duct centerline and t...

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by Horstroad
Thu Jan 06, 2022 11:58 pm
Forum: Technical/Operations
Topic: Source of bleed air (CFM engine)?
Replies: 4
Views: 1340

Re: Source of bleed air (CFM engine)?

The "intermediate" probably refers to the pneumatic system. Usually three pressure values are important for pressure regulation. PE (Engine Pressure), PI (Intermediate Pressure) and PM (Manifold Pressure). The engine pressure sensor sits upstream of the high stage valve, so it's the HPC ai...

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by Horstroad
Sat Dec 25, 2021 9:46 am
Forum: Technical/Operations
Topic: Altimeters, static pressure, and lift
Replies: 48
Views: 2894

Re: Altimeters, static pressure, and lift

An interesting question and I had to think about it for a few minutes. The static pressure component of the total air pressure changes only when you compare pressure values before and after you have accelerated the air, e.g. infront of and right on top of the wing. This drop in static pressure in co...

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by Horstroad
Wed Dec 22, 2021 12:16 am
Forum: Technical/Operations
Topic: Airspeed lost
Replies: 11
Views: 1569

Re: Airspeed lost

I don’t think you can get an A319 to do 320kts IAS at FL390 The Airbus protections would prevent the overspeed. There is no way to have the aircraft to reach that speed using autothrust with the autopilot engaged. The maximum indicated airspeed of an A319 at FL390 is 250kts at M0.82 indicated. The ...

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by Horstroad
Sat Dec 18, 2021 4:50 pm
Forum: Technical/Operations
Topic: Blue Hydraulic Pump/System in an Airbus? How does it work?
Replies: 3
Views: 1522

Re: Blue Hydraulic Pump/System in an Airbus? How does it work?

I don't think the question is Airbus specific or even axial piston pump specific, but rather a question of the basic principles of hydraulic power. If I understand your question correctly you're concerned about the fluid trapped in the cylinder on the pressurized (red) side being rotated around to t...

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by Horstroad
Fri Dec 17, 2021 10:47 am
Forum: Technical/Operations
Topic: 737 MAX APU Inlet Door
Replies: 30
Views: 3892

Re: 737 MAX APU Inlet Door

In my aircraft you never operate the APU inflight unless you need it for non-normals, relight, hydraulic pressure, electric power, etc. What aircraft has an APU that produces hydraulic pressure? For the original question I guess they changed the design to reduce drag and increase fuel efficiency. A...

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by Horstroad
Tue Dec 14, 2021 7:37 pm
Forum: Technical/Operations
Topic: Which airliners have two jackscrew assemblies to control their horizontal stabilizer?
Replies: 7
Views: 1494

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

How do these multiple jacks operate then if one hydraulic system goes down - with a jackscrew being irreversible? Unless they're placed in series (one after another) I guess, rather than in parallel (side by side) as you'd expect I can't see how they'd work. On the MD-11 the two nuts are connected ...

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by Horstroad
Mon Dec 13, 2021 11:21 am
Forum: Technical/Operations
Topic: "...low cycle fatigue fracture of a torque tube"?
Replies: 7
Views: 1092

Re: "...low cycle fatigue fracture of a torque tube"?

You are right that there is a separate torque tube inside the ACME screw

Any of these commands activates one of the two
electric motors that rotate the acme screw by applying torque to the titanium torque tube
that is held fixed inside the acme screw
.

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by Horstroad
Mon Dec 13, 2021 12:39 am
Forum: Technical/Operations
Topic: "...low cycle fatigue fracture of a torque tube"?
Replies: 7
Views: 1092

Re: "...low cycle fatigue fracture of a torque tube"?

Addenum. I think from the information on the diagram and description on page 15 that the torque tube is inside the acme screw. It is said to be made of titanium. The acme screw was recovered after the accident. Still not clear on how the fracture of the torque tube led to the fatal dive. The ACME s...

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by Horstroad
Sat Dec 04, 2021 10:00 am
Forum: Technical/Operations
Topic: Teal Color Inside A320neo Pratt & Whitney Engines
Replies: 27
Views: 5975

Re: Teal Color Inside A320neo Pratt & Whitney Engines

StereoTechque wrote:
The black inlet cowl also has visible holes on surface for Accoustic dampening.

The entire bypass duct is perforated for noise reduction.

Image

But that's the same on all modern engines

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by Horstroad
Sat Dec 04, 2021 9:18 am
Forum: Technical/Operations
Topic: Teal Color Inside A320neo Pratt & Whitney Engines
Replies: 27
Views: 5975

Re: Teal Color Inside A320neo Pratt & Whitney Engines

I was really surprised that posters were suggesting that the teal liner was an attrition/abradable lining. As you point out, the teal material extends many inches ahead of the fan. So it's not that, folks! Yes, it is. No It's not :P https://i.postimg.cc/MK30WrtC/5961041-2.jpg

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by Horstroad
Fri Dec 03, 2021 5:58 pm
Forum: Technical/Operations
Topic: Teal Color Inside A320neo Pratt & Whitney Engines
Replies: 27
Views: 5975

Re: Teal Color Inside A320neo Pratt & Whitney Engines

So back to OP's question? Why blue? Does it also have acoustic dampening properties (perforations, etc.) as the differently colored lining ahead of it? It's a honeycomb core panel with a perforated face sheet. Its purpose is noise reduction. The color is probably just the base color of the epoxy ma...

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by Horstroad
Fri Dec 03, 2021 4:55 pm
Forum: Technical/Operations
Topic: "THR CLB" v. "THR LVR"?
Replies: 16
Views: 2766

Re: "THR CLB" v. "THR LVR"?

LVR is an abbreviation for "Lever". The Airbus thrust lever does not have a LVR or "lower" detent. There is a TO/GA detent for Maximum Take Off or Go-Around. There is a FLX/MCT detent for Maximum Continuous Thrust or Flex Take Off and there is a CL detent for Climb Thrust. Thrust...

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by Horstroad
Fri Dec 03, 2021 3:49 pm
Forum: Technical/Operations
Topic: Teal Color Inside A320neo Pratt & Whitney Engines
Replies: 27
Views: 5975

Re: Teal Color Inside A320neo Pratt & Whitney Engines

The Fan Blade Rubstrip (or Abradable Shroud or Attrition Lining or whatever they're called by other manufacturers) is in the plane of the fan blades. In the pictures of that PW1000G series engines it would be the light gray ring behind the teal colored ring. The teal colored ring should be acoustic ...

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by Horstroad
Thu Nov 25, 2021 10:39 am
Forum: Technical/Operations
Topic: Restrictions on #2 Thrust Reverse L1011/DC10/MD11
Replies: 20
Views: 3330

Re: Restrictions on #2 Thrust Reverse L1011/DC10/MD11

I’m just wondering what the lockout prodcedure is for an MD-11. I remember on a 767. Installing 3 red lock plates on the outside of the trans cowl and flipping and installing a locking square drive in the center drive unit It's the same. Additionally you have to disconnect the electrical connector ...

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by Horstroad
Sat Nov 13, 2021 1:42 am
Forum: Technical/Operations
Topic: Why fuel driven actuators?
Replies: 14
Views: 1980

Re: Why fuel driven actuators?

The engines can't run without fuel. They can run without hydraulics...

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by Horstroad
Wed Nov 03, 2021 4:01 pm
Forum: Technical/Operations
Topic: Use of rudder in commercial aircraft
Replies: 18
Views: 2413

Re: Use of rudder in commercial aircraft

On the 777 Thrust Asymmetry Compensation is a protection function of the Primary Flight Computer operating in Normal Mode. It starts to operate when the CAS is >70kt, the reversers are not commanded deployed, and the thrust difference between the engines is at least 6000lb. TAC is limited to 60% of ...

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by Horstroad
Wed Nov 03, 2021 12:50 am
Forum: Technical/Operations
Topic: Restrictions on #2 Thrust Reverse L1011/DC10/MD11
Replies: 20
Views: 3330

Re: Restrictions on #2 Thrust Reverse L1011/DC10/MD11

We didn't have such restrictions.

Funny thing is, if there was a stuck reverser or any other engine problem, there was a more than 1/3 chance it was #2. Not because of maintenance, #2 always got the same love as the others. She did it just because she could.

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by Horstroad
Mon Nov 01, 2021 2:59 am
Forum: Technical/Operations
Topic: Is it dangerous when aircraft carry fuel in a center tank beneath the passenger cabin?
Replies: 43
Views: 3882

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

on planes that had/have the horizontal stabilizer tank, is that used primarily for feeding the APU? The primary purpose of the tail tank on most aircraft is for CG control. Secondary would be additional fuel storage space. On the MD-11 the APU shares the fuel feed line with the #2 engine. It has a ...

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by Horstroad
Wed Oct 27, 2021 8:07 pm
Forum: Technical/Operations
Topic: Duration of 747 Hydraulic Pressure Reduction?
Replies: 7
Views: 893

Re: Duration of 747 Hydraulic Pressure Reduction?

Aircraft that have flaps that are driven by actuators…the MD11 or DC8 come to mind…will have check valves and/or restrictors that prevent the flaps from drooping with loss of pressure. The MD-11 had the issue when you would pressurize the #2 hydraulic system without pressurizing the other two hydra...

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by Horstroad
Tue Oct 26, 2021 5:23 pm
Forum: Technical/Operations
Topic: UPS 747 takeoff without flap fairing
Replies: 23
Views: 3939

Re: UPS 747 takeoff without flap fairing

I figured it was the Preamble. The MMEL available on MBF doesn’t have that. I’ll have a peak at it at work tonight I never work with the MMEL, I think I never even had a proper look into it. There never was a need to. But I have an old copy of a MD-11 MMEL from '00 on hand and just skimmed through ...

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by Horstroad
Tue Oct 26, 2021 5:02 pm
Forum: Technical/Operations
Topic: Rather neat holes in 9V-SQJ
Replies: 5
Views: 1394

Re: Rather neat holes in 9V-SQJ

My guess is on plane tags. What I find more surprising is the fact that they didn't strip it of parts before scrapping, except for the engines and some cockpit windows. Thrust reversers still in place, slats still there... An old aircraft is usually worth more in parts than whole. If it was my aircr...

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by Horstroad
Tue Oct 26, 2021 4:51 pm
Forum: Technical/Operations
Topic: UPS 747 takeoff without flap fairing
Replies: 23
Views: 3939

Re: UPS 747 takeoff without flap fairing

But there's MEL 9.5 I don’t know what that is. It's the Preamble of the MEL. The section "Contents of the MEL" describes what is and isn't contained in the MEL and how it has to be treated when it isn't. For example Equipment obviously basic to airplane airworthiness such as wings, rudder...

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by Horstroad
Tue Oct 26, 2021 6:20 am
Forum: Technical/Operations
Topic: Is it dangerous when aircraft carry fuel in a center tank beneath the passenger cabin?
Replies: 43
Views: 3882

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

The center wing tanks usually are the largest. On the 777 (-200LR/-F/-300ER) for example the center tank holds 184,480lb and the wing tanks 69,630lb each. I think some early versions of the 777 didn't use the space in the center wing box for fuel. The two compartments of the center tank in the wings...

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by Horstroad
Tue Oct 26, 2021 5:38 am
Forum: Technical/Operations
Topic: UPS 747 takeoff without flap fairing
Replies: 23
Views: 3939

Re: UPS 747 takeoff without flap fairing

Something tells me a savvy airline would in particular leave spares of such parts at their, ahem, "more exotic" outstations. (Also, can you really not defer the flush handle but you *can* defer the entire lav? How amusing.) The way it would probably be handled by our maintenance control f...

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by Horstroad
Fri Oct 22, 2021 2:02 am
Forum: Technical/Operations
Topic: Could MD-11's used domestically do without the winglets?
Replies: 31
Views: 3606

Re: Could MD-11's used domestically do without the winglets?

Is there even a CDL for that? I know you can for 330/340, 747 and most others with wingtip devices. But my MD11 work was entirely powerplant, so I am a little curious about that. There's a CDL for the lower winglet only, but not for the whole winglet assembly. The lower winglets removed add a fuel ...

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by Horstroad
Thu Oct 21, 2021 10:38 pm
Forum: Technical/Operations
Topic: Could MD-11's used domestically do without the winglets?
Replies: 31
Views: 3606

Re: Could MD-11's used domestically do without the winglets?

The Winglet can't just be removed. While there is a removal/installation task in the AMM for the winglet assembly, it's actually the removal/installation of the whole wing tip. You would need a replacement wing tip to put in its place which would result in some (understatement) paperwork as the MD-1...

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by Horstroad
Sat Oct 16, 2021 6:24 pm
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: 14148

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

Way more problems with the hydraulic lines. Those production swages let go all the time. Replace every failed swage fitting with a Rynglok fitting and it will survive the rest of the aircraft. What an amazing and easy to use system. It's fantastic as a torturing tool - going into the stabilizer com...

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by Horstroad
Tue Sep 28, 2021 7:46 pm
Forum: Technical/Operations
Topic: Personal items left onboard American Airlines flight
Replies: 10
Views: 2502

Re: Personal items left onboard American Airlines flight

The cleaning crew will find the item, note the seat number, and hand it over to someone at the gate. They'll either make an announcement or, if it's a valuable item like a laptop and you've already left the airport like an idiot, they'll call you. Unfortunately, I've done this a couple of times. It...

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by Horstroad
Tue Sep 28, 2021 7:31 pm
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: 14148

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

Troubleshooting the PACK's on MD10/11's are always a fun time! Really? I haven't had many issues with the MD-11. The heat exchanger cracks a lot... but I guess that's a common issue for all aircraft. The 777 has it as well. Sometimes the ACM fails... but I don't recall anything that took some big b...

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by Horstroad
Mon Sep 06, 2021 7:16 am
Forum: Technical/Operations
Topic: Freighter VS Passenger variants.
Replies: 8
Views: 1913

Re: Freighter VS Passenger variants.

due to not having seats and other things Freighters aren't just empty. The cargo handling system weighs quite a bit. Also some freighter versions have reinforced floors compared to the passenger versions, like the B777. Some need additional structure to make it work, like the A330 on the nose landi...

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by Horstroad
Sun Sep 05, 2021 9:20 am
Forum: Technical/Operations
Topic: What are the pros/cons of various airliner types to the situation of runaway trim and manual trimming?
Replies: 7
Views: 970

Re: What are the pros/cons of various airliner types to the situation of runaway trim and manual trimming?

The A330 and A350 have no backup in case of complete hydraulic failure. I just looked into the B777 and there's no electric backup either. It's similar to the MD-11. Actually it's almost the same setup except for the hydraulic shutoff controlled by the cutout switches. The alternate trim levers are...

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