Questions tagged [landing-gear]

The wheels of an airplane. Sometimes replaced by floats or skis.

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8 views

What is the minimum limit required for the landing gear oleo extension on the A320?

I wanted to get some authentic information regarding as to what are limit should landing gears oleos (main and nose) be extended before maintenance action is required. Many engineers I have spoken ...
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137 views

For large commercial aircraft, how are the tires changed?

Something at least the size of a 737, all the way up to the A380. How are aircraft tires changed for large commercial aircraft? Are they actually jacked up like with a car?
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282 views

Why do some helicopters have wheels instead of skids?

I have noticed that Black Hawk helicopters have tires, but I have not seen one take off like a plane. When would a helicopter need to use a running take off or landing? When is it determined ...
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1answer
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What indication will appear in case of one of A320 LGCIU is inoperative?

What indication and where it will appear in case of one of LGCIU (landing gear control and interface unit) is inoperative?
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Why does the A-4 Skyhawk sit nose-up when on ground?

The rear of the plane is nearer to the ground, while the front part of the plane is away from the ground (see image below). Other planes are more flat. I think it was for high AoA but these planes ...
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1answer
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How does landing gear affect thrust on a light twin-engine airplane?

I'm working on my commercial multiengine rating. And I got this question from my examiner, and I answered: landing gear produces penalty drag, so it decreases thrust. But the examiner says this isn'...
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Why does only one hydraulic intake line from the reservoir have a filter on the Arrow II?

This is a portion of an Arrow II landing gear hydraulic system diagram. I noticed that there are two intake check valves, one located on each side of the pump, that would allow flow from the ...
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What is the difference between a pressure switch, high-pressure control, and low-pressure control in a landing gear hydraulic system?

This is an Arrow II landing gear diagram. In the diagram, the high and low pressure controls look like check valves. The pressure switch is unclear. What are these three items, and what purpose ...
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What is the purpose of the shuttle valve in a Piper Arrow's landing gear system?

This is the PA-28R-201 landing gear hydraulic system diagram. I am wondering how this shuttle valve functions. Research I have done indicates that a shuttle valve blocks one attachment to the valve ...
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Does Nitrogen inside commercial airliner wheels prevent blowouts on touchdown?

I just watched the first episode of Inside Mighty Machine where civil engineer-turned-host, Chad Zdenek, discussed innovations of the 747. One innovation he discussed was the increased number of ...
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317 views

How can the landing gear of an A320 be lowered in the event of a simultaneous hydraulic and electrical failure?

What is the process for lowering the landing gear of an A320 when the hydraulic and electrical systems are not operational? What happens to the aircraft when you lower the landing gear with ...
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Why complex landing gears are used instead of simple, reliable and light weight muscle wire or shape memory alloys?

Muscle wires actuators are really simple, have a high power density and are reliable. Landing gears on other hand are used only twice per flight while taking off and landing (if everything goes well ...
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Nose gear failure in single prop aircraft: belly landing or nose landing?

Let's say we are flying a single prop airplane with tricycle format retractable gear, such as a Mooney Bravo or a Piper Comache. The nose gear fails mid-flight and is unable to be lowered. Is it safer ...
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Why is the Constellation's nose gear so long?

The Lockheed Constellation has an enormously long nose gear, which causes the aircraft to slant appreciably backwards when sitting on the ground: L-049 (Image by Greg and Cindy at Flickr, modified ...
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Are hydraulic retractible landing gear possible

One of the impediments and drawbacks to extending landing gear in light of building larger engines are the larger space required for the taller gear. Would hydraulic retractable gear that works as a ...
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Are taller landing gear bad for aircraft, particulary large airliners?

Buiding larger engines for larger aircraft as opposed to smaller but many engines has proved to result in more fuel efficiency. Having established one of the main drawbacks or impediments to building ...
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1answer
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What are the three sources that are relayed to the brakes and steering control unit of an A320?

There is the sentence: Electrical signals from the three sources are relayed to the brakes and steering control unit (BSCU) and are computed into the nose steering angle. The question: What are ...
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What purpose of the thermal relief valve in PA-44?

In landing gear part, As I know, the valve will open to relieve pressure as a result of temp and pressure changes as airplane climbs or descends, but I do not know What purpose of the thermal relief ...
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Why would one plane in this picture not have gear down yet?

This image (as posted in another question) is a YouTube video's thumbnail: I noticed that the lead twin (737?) has gear down, the 747 behind does not (appear to) have gear down, but the third plane ...
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Why Buy A C182/172 Instead Of An C180/170? [closed]

So a thought came to my mind which covers not only Cessna planes but all others. The Taildraggers need a little bit less runway becayse AOA on takeoff is good and that AOA eliminates the need of ...
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How does pulling back provide better steering during rollout for light GA planes?

I had requested clarification on an answer to the question, How do I keep a C172 straight on the centerline during landing/rollout? I did not comprehend how pulling back after touch down provides ...
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1answer
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How to understand the kinematics principle behind landing gear retraction system (or 4 bars system)? [closed]

I would like to know about the principles of landing gear retraction system and I struggle to find clear information about it. It seems to be about a four bar systems in most cases but I would like ...
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Why don't nose landing gears have brakes?

Nose brakes can help the aircraft in braking and it can also help in reducing the travel on the runway length. So why don't we use brakes in the nose landing gear?
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How can I find the communication with ATC following an aborted landing?

On February 7th, I was on a UA 4694 from DEN to SAF, upon approach the landing was aborted; upon second approach, we heard the landing gear come down, which we did not hear on the first approach; the ...
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1answer
222 views

How does retracting the gear affect weight and balance?

In many of the POHs, in the W&B section it is indicated that there is a moment change due to gear retraction. For example : Moment change due to gear retraction +780 in-lbs. Two questions : If I ...
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Wheel or skid? Which advantages does each one have when used as the landing gear system compared to the other one?

I would like to discuss this topic in depth, as I have not found a clear answer yet. Which are the advantages of using skids instead of wheels (or viceversa) for the following considerations?: -As ...
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Why don’t aircraft use run-flat tyres?

Tyre failures on aircraft during takeoff are fairly common, and are usually (though not always) caused by flat or underinflated tyres (via the overdeflection and overheating experienced by tyres with ...
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1answer
195 views

Do airplanes have sensors to detect landing gear fires?

Given that retracting a landing gear that happens to be on fire is a suicidally bad idea, for reasons that should be immediately obvious, do airplanes have temperature sensors on their landing gear in ...
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Landing gear sequence [duplicate]

{With reference to this video} Is there any particular reason that land gear retract half way then 2nd gear retract half way and then proceed to retract completely. Is it related to center of ...
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What are the potential threats of having the landing gear dirt from mud in a rectractable landing gear airplane?

Recently I have been flying an aircraft with the landing gear very dirt with mud due to the parking area of the airfield on grass and the meteo conditions in recent days. I wonder what are the threats ...
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4answers
264 views

How can drag induced by the landing gear be reduced?

What are some of the methods used to reduce the drag caused by the landing gear for aircraft with non-retractable landing gear?
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1answer
212 views

Does the PA-44's squat switch disable the stall warning?

I've read the AFM and looked online about the gear system for the PA-44 Seminole and there is apparently a squat switch on the right main gear that disables the stall warning whilst on the ground. ...
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Do military bases still employ wheel watchers?

When I was in the air wing in the '70s, I had the unpleasant opportunity of pulling wheel watch. The unfortunate individual sat in a small shack (maybe 3 x 6 ft.) with a pair of high-powered ...
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What is the purpose for two nitrogen charged chambers in an oleo strut?

What is the purpose of a twin nitrogen charged chambers oleo, such as the one illustrated below? Why is it used and what are the advantages compared to a conventional mono-nitrogen chamber? Training ...
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How often is a tire replaced on a 777?

Given that it is long haul aircraft, and is most widely used by airlines in that capacity: How often do they replace the whole tire? How much does 1 tire cost the airline?
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Are all tires on an aircraft replaced at the same time?

On cars, it is often to replace all four tires at the same time. Is this true also for aircraft? I imagine the nose gear and main gear probably can be replaced at different intervals. However, are ...
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Are there any aircraft with powered landing gear?

My student asked me a question this morning. It was: A car drives by turning its wheels against the Earth. An airplane taxis by rolling on its wheels while the engines push against the air. Are ...
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How to determine the maximum servo torque required for a nose gear?

It's pretty much it. I know how to calculate the friction force on the nose gear for a three-point landing condition using the method set forth in ...
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1answer
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What did the “gear warning horn” on the North American P-51 sound like?

I'm working on a sound project for a P51 simulation and I'm having real trouble trying to find a reference on how the P51 gear warning horn sounded like. What mechanisms were used in the '40s to make ...
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How is a light plane's nose wheel straightened during retract?

Assuming a light aircraft has direct cable linkage to the rudders, during taking off in a very strong crosswind with the pilot correcting with hard rudder, what keeps the nose wheel from remaining off ...
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Has there ever been an uncommanded lowering of landing gear?

Has there ever been an uncommanded lowering of the landing gear on a large commercial jet? I could not find any instance of it in a preliminary google search. Could a simple short-circuit cause such a ...
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Could a plane land on specialized vehicles if its landing gear failed?

This (fake) video has stirred up a lot of questions online about whether such a scenario would be possible in reality - and the answer to those questions appears to be a resounding "No, that's very ...
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Is it possible to remove an A320's main gear using one main jack and one nose jack?

I have only one set of jacks (nose-main LH and RH) and I need to swap the main landing gear from one aircraft to another. I don't have a dummy landing gear. Is this possible?
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Do Airbus aircraft have an “off” position for their landing gear?

I know some Boeing aircraft feature an up, down, and "off" position for their landing gear lever. I know that some Boeing wide-body jets do not have a 3rd lever position, but still have an "automatic" ...
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How much more economical are planes with retractable gears vs. those with fixed gears?

Many small planes have fixed gears, some have retractable gears. All things being equal, the plane with retractable gears would have to be more expensive than fixed gears, as the mechanisms involved ...
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What are ways to reduce drag and noise generated by the landing gear?

Apart from using fairings, what ways are there, or have been studied, but not necessarily implemented in reducing drag and noise produced by the landing gear, mainly for commercial aircraft with ...
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How is tire rubber removed from the runway?

Every time an aircraft touches down, the tires are spun up rapidly. As a result, some rubber is left at the touchdown zone. (image source) As time goes on, more rubber is accumulated at the ...
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Why do landing gear tires smoke upon touchdown?

I have been observing several aircraft landings and have noticed that when the aircraft's landing gear touches down, it precipitates the rising of a cloud of smoke. Why is this? (Source: airliners....
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358 views

Are nose wheel tyres designed differently from the main wheel tyres?

For the heavy large Jumbos like the Airbus A380 and the Boeing 747-800, considering nosewheel tyres are not subjected to the excessive heating caused by braking from the disks and brake pads, and ...
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458 views

What is the air temperature inside of a tire right after landing?

What is the maximum design air temperature inside of a tyre of an Airbus A380's and a Boeing 747-800's main gear fitted with brakes, before landing after a 10 hour flight and right after landing? Are ...