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Post by RonMiller on Feb 25, 2007 12:00:41 GMT -7
*bear in mind I've never been in a cockpit of a turboprop or jet plane.
So, I am seated in the plane, and I am ready to start it. Now, If I had all the proper training I'd know this but since I dont I'm one of the Inquiring minds wanna know bunch.
How do you start it? On some of our tractors there is merely a pushbutton and you push it and the ole boy runs if you turned the fuel shutoff on. Other tractors like our JD tractors use a key start switch, and by the way, one key fits all for the most part. So I can take our key and go start the neighbors tractor. Do planes have a different key for each plane like a car?
Once then the plane is done for the day, do you just merely shut the fuel off to the engines for them to die and do you have to let them idle a few minutes like a turbocharged engine to let things cool off a bit and let things slow down?
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Post by jetmex on Feb 25, 2007 17:05:01 GMT -7
The start sequence on all the newer generation airplanes is completely automatic, controlled by an EEC (engine control computer). Basically, you select an air source (most jet engines use pneumatic starters), from either a ground cart, onboard aux power unit (APU) or you can use air from another engine that's already running. Select ignition to ground start and hit the start switch. The engine will begin turning, when it gets to between 18-30% RPM (depending on the engine), you move the fuel valve lever/switch to on. After a few seconds, you should hear the "whoof" as the engine lights off, and watch the RPMS, exhaust temp, oil pressure etc start indicating. At about 40%, the starter cuts out and the engine will accelerate to its ground idle speed. The ignition also cuts out (the combustion process is self sustaining once the engine is running). If any parameter goes out of limits (overtemp, no acceleration, etc) the EEC will abort the start.
On the older jets, the pilot did all the automatic functions. Same basic procedure, but the OPS (organic pilot system) had to do the rest. There was no autoshutdown feature and no EEC, so you had to be fast on the controls if something happened. On older airplanes with electric starters, you had to pay real close attention to everything, because electric starters draw huge amounts of current for an extended period of time, and now and again the battery voltage would start to drop during the start sequence, which could have all kinds of interesting effects.....
Shutdown is basically by turning the fuel switch off.
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Post by RonMiller on Feb 26, 2007 0:42:16 GMT -7
Ok, but is there an "ignition switch" that you stick a key or something in? And then if there is a key, would it start other planes or are they keyed different like cars, meaning my key wont turn the ignition switch on yours.
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Post by jetmex on Feb 26, 2007 8:29:19 GMT -7
For jets and bigger recip engines, there is no key. Most smaller general aviation airplanes still have a key to start them, the key being used to select the magneto you're going to use to run the ignition system, lock the doors, and to engage the starter. For airplanes with no electrical systems, you start them the old fashioned way by swinging the prop by hand. The keys are like car keys, each set fits an individual airplane. It's not foolproof, though. There was a time when Craftsman tool box keys could get you into quite a few GA airplanes..... ;D Our airline has 335 aircraft, and close to 6000 pilots to operate them. Can you imagine how many keys that would be? And we'd have to track them all as well.....  |
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