| Tue, Mar 30 2010 08:15pm IST 1 |
Ram Kapoor
9 Posts
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What if the ailerons jammed in flight?
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| Wed, Mar 31 2010 07:12am IST 2 |
James gibs
81 Posts
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The function of ailerons is to enable a plane to turn left or right
in flight. They are hinged control surfaces attached to the back of
the wings so that when one goes up, the other one goes down; the up
going aileron reduces the lift whilst the down going one increases
the lift. This produces a rolling moment that enables the plane to
turn when the pilot in the cockpit moves the control column
(steering wheel).So, is it critical if the ailerons ceased to
function? Depending on the type of plane involved (light single
engine aircraft or large commercial jets), it does pose a problem
but it is not entirely a life and death issue. Some form of control
is still possible.
Yes, in the event of loss of the ailerons, some degree of roll
control is available by using the secondary effect of rudder.
While not an efficient way to turn the aircraft, a pilot has at
least some directional control. Short or rapid bursts of power
may increase the effectiveness of the rudder to some degree. It
can act as a form of torque and slipstream effect. So, an
aircraft with a jammed aileron can indeed be landed in a slip,
preferably against a crosswind.
Well, its all about the ailerons.
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| Wed, Mar 31 2010 07:36am IST 3 |
Ram Kapoor
9 Posts
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Thanks but what happen when all the control surfaces ceased to
function?
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| Wed, Mar 31 2010 07:46am IST 4 |
James gibs
81 Posts
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Wow! It would be a nightmare! In such a situation, the only
available method of controlling the aircraft was by adjusting the
throttles of the remaining two engines; running one engine faster
than the other to turn the plane, and accelerating or decelerating
in order to gain or lose altitude.
On the Boeing 777s or the Airbus A320s - when all the main flight
controls are lost due to either hydraulics or total electrical
problems, we still have the mechanical back-up to steer the plane
and provide a degraded form of control for the planes.
With a better flight control and refuse-to-crash technology, I
can see that the airplanes of the future will definitely be a
marvel - with no worries of controls failures!
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| Wed, Mar 31 2010 07:51am IST 5 |
Ram Kapoor
9 Posts
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What happened when all the engines also failed in Air? Total
failure.........
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| Wed, Mar 31 2010 08:01am IST 6 |
James gibs
81 Posts
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This is a very interesting question. When all engines are failed
during flight, not all hopes are lost my friend ! Have you ever
heard of gliders flying ? Well, gliders fly without any engines!
Okay, I am being too simplistic. Nevertheless, all aircraft can
glide to a safe landing but the degree of distance flown varies.
Gliders can stay in the air for a long time. Single engine aircraft
encountering an engine failure can also glide a fair distance to
execute a safe landing provided it has the height.
I am sure your question concern commercial aircraft. Firstly, I
must say that all commercial aircraft engines are very reliable and
to have all the two, three or four engines failed totally on them
are very, very rempte. Of course, I am not going to argue with the
Murphy's Law that, anything that can go wrong will go wrong.
when an airplane encounters all engines failure, does the plane
start flipping and crash, or continue to fly while losing height?
If it continues to fly, how long does it last and how safe it is
to land the aircraft ?
the aircraft does not flip or crash. It continues to fly at an
optimum gliding speed, a speed much lower than its cruising
speed.
However, it may not be able to maintain its cruising altitude but
continues to lose height at a rate of about 3500 to 4500 feet per
minute. This will give an aircraft, cruising at 35,000 feet about
10 minutes to fly a distance of about 40 to 50 nautical miles.
Remember, pilots have been trained to restart/relight the engines
whenever they encounter total engine failures. If restarting the
engines were unsuccessful, they would have no choice but to carry
out a prepared forced landing - just like what the Canadian pilot
did to the crippled Boeing 767.
If you were a passenger on board this ill-fated aircraft, how
would it feel like ? Although I have never encounter such an
experience as a passenger, I have practiced this exercise many
times and have been tested thoroughly in the aircraft
simulator.
This is what will likely happen if you are in the passenger
cabin. Firstly, if both engines failed simultaneously (very, very
unlikely, but normally one after another), the noise level will
drop very rapidly. The cabin lights will flicker and may be a bit
dimmer. If the aircraft auxiliary power unit (something like a
standby generator-cum compressor) fail to start automatically,
you will feel the slow depressurization in your ears. Oxygen
masks will drop from the ceiling and an automatic emergency
announcement will be made through the Public Address System
shortly. The cabin crew will then brief you the emergency
procedures for a possible Forced Landing or Ditching.
How safe is it to land ? In a Boeing 777, with both engines
failed, it is still controllable even though most of the normal
hydraulic system pressures would be lost. However, there is the
emergency hydraulic pressures generated by the Ram Air Turbine
system (RAT). The RAT will automatically extend when it senses
both engines had failed. There are fan blades on the RAT which
will turn to generate hydraulic and electric power as the
aircraft glide forward at a speed of about 180 to 280 mph. The
landing gears would be extended by the emergency alternate system
and the aircraft has sufficient brake pressure to bring the
aircraft to a complete stop using the emergency accumulator
pressure.
In a nutshell, if an airplane encounter all engines failures, it
is capable of gliding to a safe landing provided there is a
suitable landing area. The landing gears would extend and the
brake would still function to stop the aircraft safely. So all
hopes are not lost !
Hope that answers your question.
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| Wed, Mar 31 2010 02:35pm IST 7 |
Vishu Cool
10 Posts
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Very well said sir...
Also have a look at British Airways Flight 009, a 747, which
experienced all four engine's failure in flight but were able to
successfully restart the engines and land safely...
@ James sir
So sir is it possible that when an RAT gets extended, which
provides hydraulic and electric power, if the glide speed decreases
but its still 20-30 kts above the stall speed of the aircraft , the
controls of the aircraft will be less responsive to the inputs from
the pilots...???
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| Mon, Aug 2 2010 03:45am IST 8 |
HAWK 21M
48 Posts
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Most Control surfaces have Breakaway cams in the system to cater to
jamming.
RAT does not always provide both Electrical & Hydraulics,it
depends on the type.
Eg On B757 the RAT is a Hydraulic provider & the HMG supplies
emergency Electrical.
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