New answers tagged boeing-737
9
The problem is that there is no redundancy in the sensor input. The quote from the article is:
This original version of MCAS, according to two people familiar with the details, was activated only if two distinct sensors indicated such an extreme maneuver: a high angle of attack and a high G-force.
So on the original design, MCAS activation required two ...
2
That's a completely incorrect understanding of the article. The summary should be:
MCAS activates if:
a) Sensor detects a high angle of attack
and
b) Sensor detects a high normal G load
If one sensor is erroneous and and the other one isn't, then MCAS would not erroneously activate.
-2
I do not believe the teaching in the patent is correct.
Instead of the downwash from the strake suppressing the wing upwash (and remember, the other side of the vortex adds to the wing upwash!) we believe that the vortex is well organized and can withstand the adverse pressure gradient of the wing better than the 'junk' wake of the nacelle without the ...
6
At night, at that range, it will look about like a dot of light, probably with a red flashing beacon and white flashing strobe lights.
That's what you'll see from essentially every aircraft at that range at night, unless the pilot chooses to turn off some or all lights.
But you're seeing the LIGHTS, not the AIRCRAFT, at that distance, and the ability to ...
2
To generate thrust, engines need fuel and air: a spark will ignite fuel (by getting heat, above the ignition point), which burn with the oxygen in the air.
On this (and other incidents), together with air, also rain (and hail or snow) in the engine, so the spark is not enough to ignite the fuel, and so the engines stop working. So, this is the important ...
3
You are getting the APU mixed up with the RAT:
The Auxiliary Power Unit (APU) is an engine powered generator, either a gas turbine or a piston engine. APUs deliver enough power to start engines, power cabin lights, cockpit instruments and radios, and in some cases power hydraulics. Often the APU can only be run at lower altitudes where the air is thicker
A ...
3
From publicly available sources, the first motive of the MCAS was to satisfy the stick force per G requirements, or maneuvering stability (not static longitudinal stability, which deals with speed stability). This is confusingly captured in 14 CFR 25.255(b) and (c) under Out-of-Trim Characteristics, but also applies broadly to buffet characterization at mid/...
8
The Boeing 737 MAX MCAS system is there ONLY to meet the FAA longitudinal stability requirements as specified in FAR Section 25.173, and in particular part (c) which mandates "stick force vs speed curve:, and also FAR Section 25.203 — "Stall characteristics".
FEDERAL AVIATION REGULATIONS Sec. 25.173 — Static longitudinal stability.
Sec. 25.173 — Static ...
2
The MAX feels like the NG, which feels like the Classic, which feels like the -200. The flight control artificial forces are identical across the different versions, which share a type rating. No need for MCAS there.
Also, the MAX is longitudinally stable. MCAS was implemented for tackling some situations in extreme corners of the flight envelope, as ...
4
The fuselage length is immaterial. The problem of the Max series relates to the positions of the engines versus the wing, and their aerodynamic interference near the at high alpha. The amount of fuselage ahead of the wing or behind the wing is not a major factor here.
4
The MAX 10 fuselage is also lengthened behind the wing:
In October 2016, Boeing's board of directors granted authority to offer the stretched variant with two extra fuselage sections forward and aft with a 3,100 nautical miles (3,600 mi; 5,700 km) range reduced from 3,300 nautical miles (3,800 mi; 6,100 km) of the -9.
Wikipedia: Boeing 737 MAX 10
...
2
Unfortunately the short and simple answer is money. They weren't prepared to spend the money on a costly redesign of the already proven 737NG fuselage.
The best in depth explanation I've seen of the whole issue with the MAX is: "How the Boeing 737 MAX disaster looks to a software developer".
4
Aircraft weight, slope of the tarmac, and headwind or tailwind play a huge role in this. With a heavy aircraft, it can take significant power to start moving. However, a light aircraft, particularly with a little tailwind or favorable slope, may be ready to roll with idle thrust as soon as the brakes are released. The Max aircraft, particularly, generate ...
10
From the 737 (Classic and NG) normal procedures section of the flight manual:
Aircraft response to thrust change is slow, particularly at high gross weights. Idle thrust is adequate for taxiing under most conditions. A slightly higher thrust setting is required to start taxiing. Allow time for aircraft response to each thrust change.
To initiate taxi,...
2
The technical answers above are fairly good, but probably the biggest answer is that Boeing corporate out in Chicago was simply too miserly to invest in a clean sheet airplane (which it could have EASILY done) and demanded that Boeing Commercial Airplane develop this new medium range airliner on a limited budget within a limited time span. The 737 MAX ...
1
Boeing's main problem was time to market - they were in a tremendous hurry to compete with the latest Airbus. Re-engineering the undercarriage would have been more complex and taken a lot longer than adjusting the design of the new engine pylons.
Perhaps ironically, the latest Max 10 has had the time to develop an extending undercarriage, giving it 9 inches ...
6
Because lengthening the main gear struts constitutes an almost complete structural re-design of the main wing structure, with dramatic consequences on cost, lead time, re-certification, weight increase etc.
The main landing gear of most swept back winged aeroplanes retract behind the rear spars, in the kinked section close to the fuselage. Picture above is ...
2
There is a limit to what can change on an air-frame before being considered a new aircraft. I mean new as in a whole new designation. That means a whole new approval cycle that may or may not be approved by the FAA or international organizations.
Moving a pivot point is not a simple task, there is a lot of structure to move. If you move structure there is ...
19
The main gear sits between the wings and retracts inwards, such that the wheels will rest in the lower fuselage. Lengthening the main gear would either require to shift the gear attachment points outward or to retract one leg a bit forward and the other a bit backwards, such that both wheels will sit behind each other instead of side-by-side, as they do now -...
-2
The fuselage is not wide enough and therefore there is not enough space in the wheel well to store two main gears, had they been extended further.
MAX 10 employs a new landing gear design that shrinks the legs slightly, but even that is just on the limit of what is possible, so if Boeing increased engine size for all models and used that mechanism for MAX 7,...
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