55

MCAS doesn't have its own on/off switch It is a fly-by-wire feature designed to account for a particular flight regime that would not (or was not expected to) be encountered very often in normal operations, and is intended to account for some of the aerodynamic effects of the LEAP-1B (CFM International) engine installation for this model. Its activation ...


28

No. It doesn't have an APU — it has two of them. They are located close to the main landing gears. From An-225 Mriya is the world’s largest aircraft (English version): Auxiliary power plant consisting of two TA-12 turbofans installed in the left and right chassis fairings provides independent power to all systems and starts the engines. I think "...


23

Depends on the system in question, but typically the following indications will serve as a means to verify that a system is functioning correctly. Activation lights - some cockpit switches will illuminate when commanded by crew. Granted this only can serve as an indication that the switch was engaged. Indicator lights eg landing gear position lights, etc -...


20

You can disable the stabiliser trim which will prevent MCAS from making inputs to the aircraft.


13

Synoptic refers to the active system diagrams that are selectable, usually on one of the middle displays above the center console. If you want to know what the hydraulic system is up to, you can select the Hydraulic Synoptic and an active diagram of the hydraulic system appears, showing what's pressurized and what's not, valves open and closed, the ...


12

On the 737 NG, at high angles of attack, the nose of the plane would naturally pitch down, helping to recover from a stall and to increase airspeed. The larger engine nacelles on the 737 MAX are located forward of the center of gravity, which means that at high angles of attack they are pushing the nose up. MCAS helps to push the nose down in this situation,...


11

You can't. Most of these airplanes are flown with hydraulically powered control surfaces with no mechanical input possible from the cockpit flight controls. The flight controls just operate servo control valves in the hydraulic actuators, like the bucket on a front end loader but a little fancier. If it's FBW, the FBW system does the same thing at the ...


11

All flight guidance functions and their changes are shown on the Flight Mode Annunciator (FMA) and have corresponding switches on the Flight Control Unit (FCU). The buttons on the FCU are usually lit when activated, and the mode is shown on the FMA. Other systems, like pumps, generators etc. have pushbuttons that are lit when activated (or deactivated, ...


10

From what I have read, the other answers explain the cutout procedure correctly. Edit: The ongoing investigation appears to reveal that the aerodynamic forces on the stabilizer may become so high that it becomes hard or impossible to manually correct a nose-down trim. (This is not a B373 MAX issue but concerns earlier models as well.) The forces increase, ...


9

Here's an answer for the B737, from own work compiled from several public sources. The A320 and other airliners are very similar. The air conditioning packs are Air Cycle Machines (ACM) which remove heat from air through a reverse Brayton cycle. Hot compressed air is cooled and then expanded, which drops the outflow temperature to a temperature cold enough ...


9

Oddly enough, I was able to find quite a few descriptions for the word, all of them defining synoptic as presenting a summary or a general view of something, and in my opinion, the meaning of the word is best described in Wiktionary by the etymology of the word: Ancient Greek συνοπτικός (sunoptikós, “seeing the whole together or at a glance”), from ...


8

A performance increase after a compressor wash is expected to happen, but it does not return to the original performance as there are more degradation mechanisms at play. This answer explains that organic build-up causes a change in airfoil shape causing the recoverable performance degradation. Another source may be deposition of salts and dissolved ...


7

In the architecture lingo, the dado is the lower part of a wall below the dado rail. The grille portion of a passenger aircraft wall is called the dado module. It consists on a louvered air grille over a decompression panel (sometimes called the dado panel) which can be open or closed. Boeing patent for a decompression panel, source The cargo compartments ...


7

characteristics copied from Airbus More precisely, copied from the package developed for Airbus by Thales. Thales pioneered the development and certification of FBW technology on modern aircraft, starting with the Airbus wide-body A310 in 1983 followed by the A320 family (...) To that regard, from an official brochure (PDF), the SSJ100's avionics are ...


7

Typically, both pilots will set up "their" stuff as prescribed in the airline SOP's, and then the checklist will be called for. At my airline, the captain has certain switches that he sets and certain systems that he checks -- generally things on his side of the overhead panel along with his flight instruments -- and the FO does likewise. The FO performs ...


7

No, the 737 NG stabilizer trim system does not feedback from AOA. My source of information comes from this LinkedIn Slide Share and corroborated by this online FCOM. There are several ways through which the stabilizer can be commanded: Manually via the trim switches. Manually via the trim wheels. Automatically via the Speed Trim System (STS). A helpful ...


7

Short answer: They're antenna(s) for the onboard VHF radio(s). Airplanes aren't actually required to have radios. But, if you want to fly into certain classes of airspace, you must have at least one VHF radio on board, to communicate with air traffic control. A lot of planes (in fact, I would say the majority of them) actually have two radios installed. ...


7

As @Bianfable points out in the comments RVSM airspace is a problem but ignoring that for a minute: The question of will they continue? depends on the airlines op-specs. Different airlines will handle this differently and it may very well be handled different on different airframes within an airline. A call to base may even occur but there are lots of ...


7

No, many aircraft don't have them, like the Cherokee since it uses a gear warning horn. The horn signifies that the gear isn't down and you don't want to confuse that with the stall warning, so they don't have one. 23.207 says that an audible or visual indication is not required as long as the aircraft exhibits a "warning" 5 knots before the stall, in the ...


7

Yes, helicopter blades are no different from wings and propellers when it comes to ice, and there exist rotor de-ice and anti-ice systems for helicopters that require the ability to fly in known icing conditions, typically military types. Some examples include the Sikorsky S-92 and MH-60, and the Kamov Ka-50. Rotor anti-icing systems are usually electric ...


6

A change in the pitch feel system wouldn't solve the problem. It's the MAX's natural behaviour separate from the flight control system (that is, behaviour when you aren't touching the controls). As Fooot says, the MAX's engines have the effect of moving the overall center of lift forward somewhat, which is more or less the same thing as moving the center of ...


6

The A320 has an emergency gear extension handle to deploy the landing gear by gravity in case of electrical, hydraulic, or mechanical failure. To force the landing gear to extend, one of the crew must pull the emergency gear extension handle up, then turn it clockwise three turns. The cutoff valve then shuts down hydraulics to the landing gear system and ...


6

Only small planes can fly without power actuation. The largest size airliner that can be flown manually would be about a B737, which actually has manual back-up for the elevator & ailerons as in this answer. The B737 uses a balance tab to assist in lowering the hinge moments during manual actuation. In a much larger aeroplane like the DC-10, there is no ...


5

MCAS is basically an artificial stability system for the flaps-up low-speed regime, autopilot off, that is what I would call clever a band-aid solution to a pitch instability problem that showed up in development. If you are hand flying at low speed and are trimmed at, say, 190 kt flaps up, and the airplane is on trim speed, the nose should be rock solid ...


5

Irrespective of 737 MAX MCAS, I haven't seen similar decision relying on a single sensor on 777 or on 757. Similarly I found nothing similar on Airbus 320, 330, 340, 350, or 380. On these Airbuses, 3 sensors are used for critical decisions, thus the faulty sensor is isolated by voting the data. If the 3 sensors are diverging (no 2 sensors giving similar ...


5

Why is it designed like that? This design combines two advantages: The system works reliably with one filter instead of two, saving a bit of cost, weight, and complexity In case of a blocked filter, the gears can still be lowered (thanks @GgD for the hint!). How it works Gear down: When the flight deck gear selection handle is put in the gear-down ...


5

The compressor blades accumulate a coating of organic material from the atmosphere on the blades, which in the later stages, where the temperatures get above the material's flash point, may be mostly carbon from cooked organic material like pollen and bugs (the same sort of blackened accumulated crud you'll see on the butterfly of a late stage compressor ...


4

Speed Trim System (STS) is very similar to MCAS and is used on the same aircraft. Moreover, Boeing maintains that it did not have to notify pilots about MCAS because MCAS is a part of STS, running on the same computer and controlling the same surface — the stabilizer. In a way, MCAS is just an extension of the system that already existed on prior versions ...


4

All large swept-wing aircraft have a yaw damper, which is always active. It takes an input from a yaw gyro and applies rudder inputs in order to counter Dutch roll.


4

Are there other automated systems providing direct control surface actuator inputs when autopilot is off on the Boeing 737s? One such system on the 737 Classic and NG is the Speed Trim System: As you can see above, when certain conditions are met, of which 5 seconds has passed since a pilot trim input is made, the STS trims the plane if required. The ...


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