Air Craft

[bernard]

Hi

Can anyone repair aircraft air con,or is this covered by special regs.

Regards Bernard

[chemi-cool]

Its just like a vehicle air condition.

But I'm sure that The UK GOV. have found the way tomake it very complicated :D

Chemi :)

[botrous]

Its just like a vehicle air condition.
Chemi :)

There are 2 types of air craft A/Cs the first is called ***** pack and is used in old models shipping aircrafts and still in use on some and on none propolsion engines air crafts ....It works like a conventional AC

The second that's the newest is called (detente d'air) sorry for using french but the word to word translation is air expension , and is on jet aircrafts , and works by taking air from the stage nine (at this stage the air is the most clean) of the aircraft turbine , compresses the air than expend it , the tempreture of the expended air can go to 0 C

[Peter_1]

While studying for my ATPL, we also saw the working principle of the airco system.

It's like Botrous said but they also use ***** compressors on the small commercial airplanes and all the no-turbine aircrafts.
You need turbines and compressed air to make cold air via the Joule-Thompson expansion cycle.

If you Google, you will find a lot of links.

They also use this compressed air to pressurize the aircraft body to a certain DP. This pressurizing starts already on the ground and is gradually driven up as soon the doors are closed and the airplane backtracks from his gate. You can feel in your ears that their is a pressure change. They start it that soon so that they can do it very smoothly, especially for the kids. They dial in the desired pressure and the time.

Something I always remembered from my theoretical training: if pressure should fail immediately (rapid decompression) at an altitude of 35.000 ft (or FL350, cruising altitude) due to a door failure, then the pilot has to make a sudden very steep emergency dive till the outer limits of the plane.
Pressure is that low on that high altitudes that almost instantly N2 bubbles will form in your vanes. On that moment, you need pure oxygen. So when the oxygen masks fall out the ceiling you have less then 10 to 20 seconds (!!) to put them on, otherwise you're dead.
The oxygen that's flowing in your mask is coming from a small bottle or from a small oxygen generator but it can supply only for some minutes oxygen.
The pilots receive oxygen with a flow rate +/- triple that of the passengers. If they do not reach 10.000 ft within some minutes, then all the passengers will die.
So grab those masks as soon as possible.

One of my instructors told us that he once was at Airbus in St Nazaire France to train this emergency with a for this training special constructed airplane - I think it was a Falcon.
He was very impressed and had thousands of hours on a B747. He said that if he ever had to do this with a B747, that the airplane would brake in pieces.

You must be qualified when working on an airplane, whatever you may do on airplane, even if it's just tightening a bolt.
It's also clearely written what a pilot may do but these are only checklists and sometimes, you may fill the oil and the fuel.

[Brian_UK]

Bernard

No special regs for aircraft a/c. Used to do Cessna twins and singles.

The compressor is normal driven by an electric motor in the nose cone of the aircraft.

If you get an engine driven compressor on a single engine plane then make sure that you have some long hoses; this enables you to sit in the c0ckpit safely while the engine is running - do NOT approach the rotating prop ;) :D

Leak testing is a complete pain, the piping runs under the floor, dashboard, seats - you name it etc.

Treat it like a car and you won't find anything extra special. Just remember that all screws, nuts and bolts and tools MUST be accounted for at the end of your visit.

Have fun with them.

[Brian_UK]

Forgot to add Bernard, double check that anything you plan to add to the aircraft is approved by the engineer you are working alongside; no special drop-ins for old R12 systems - they have to change to R134a (another story).

[frank]

You need turbines and compressed air to male cold air via the Joule-Thompson expansion cycle.

hi Peter

I haven't "Googled" but is this also known as the "bootstrap" type of aircraft AC?

[Peter_1]

It's indeed the same .
See http://projects.bre.co.uk/aircycle/fig3a.jpg and http://pdf.aiaa.org/preview/1969/PV1969_787.pdf

[Peter_1]

Brian,

The JAR 21 and 145 and very specific JAR 66 states that the technician needs at least a JAR qualification B1.
You can do it of course under supervision of an approved B1 technician but he will remain responsible for your work.
That's the European law.
We know of course that an airplane airco is exact the same as a car airconditioning but you may not touch it legally

[Brian_UK]

Agreed Peter, yes I always worked alongside the technician at all times. I suppose you could say that he became my assistant but had the upper hand...