Location: turn L @ Taupo, just past the Niagra Falls...
Cold start: the book should work. Give it fuel, air and an ignition source, it'll run. Any klutz can cold-start a 520/550 -just don't over-prime/flood it.
Hot/warm starts are where life gets a bit more interesting. Speaking broadly, the issue is that fuel entering the engine often vaporises in the fuel lines above the hot cylinders prior to reaching the FCU. You need to purge the lines, replacing the vaporised fuel with clean, cool fuel from your tanks:
∑ Throttle fully open (in),
∑ Mixture to idle cut off, (out) and
∑ Full electric fuel pump for about ten seconds.
This procedure cycles the heated fuel back through the return pipe and replaces it with cool stuff from the tanks. Then set your throttle and mixture as per the AFM, or anything that works. Crank the engine. Once started, it will most likely die after a few seconds, so be ready to catch it with the electric pump briefly. It should run smoothly from there. Do not over-prime as the excess fuel can gather in the bottom of the cowling and catch fire. If there are leaks in the fuel-system, it may happen anyway. These fuel fires can be hard to spot because they donít make much smoke, so look out for bystanders getting all agitated or check a shadow of the cowling for distortion. If necessary, just keep cranking the engine to suck the flames back inside the induction system. An engine-start is the best solution; it will either suck the flames in or blow them out.
If history is any indicator, you'll get heaps of contradictory advice as the thread grows older... hands flying everywhere in some.
This has worked for me in the past!
Last edited by RadioSaigon; 22nd Aug 2012 at 14:33.
Cold start: Mixture rich, throttle cracked, prime while watching the fuel flow meter. The needle will rise pause and then rise again. As soon as you see the second rise get of the primer and hit the starter she will go in a couple of blades everytime
Hot start: Throttle cracked mix rich no prime. Crank and she will usually pick up right away on the vapours remaining in the system but will start to die again after a few seconds so you have to be ready to give it a blip of prime to keep it running
Warm start: It sucks to be you . She can be a right bitch. I usually give it a shot ( 2secs or so ) of prime an crank. If it doesn't pick up after cranking for a while slowly open the throttle while continuing to crank.
If you don't know what to do deliberately flood the engine so you know where you are and then crank with the throttle wide open and the mixture at ICO. it may take awhile but it will eventually always start, you just have to be ready to get the throttle back and the mixture up as soon as it fires
On c-206 with conty-520, I usually open the hatch on the top of the cowling after the flight, so the hot air doesnt collect inside the cowl.
My procedure for hot start is: master-on, mix-out, throttle-open. I then push fuel pump on for about 10sec. After that, I prime the engine for about a second or two (mix-in, throttle in, fuel pump-on-off). Then throttle 1/2inch-in, mix-out. Then I start to crank and slowly advance the mixture in. At about 2/3 mix-in the engine usually starts.
The list below is really for situations either you have failed to start a few times or where you know that aircraft will not be easy to start. Having flown regularly with Continental GTSIO-520s, some of the trickiest to start while hot, there was one technique that always works, and works for a very logical reason. It is basically Big Pistons Forever's last suggestion, with a bit more detail.
1. Over prime the engine. Use the aircraft's priming technique, be it a special priming pump, the electric fuel pump or simply exercising the throttle, but do it excessively. Now you know you have an over-rich mixture, not an over-lean mixture.
2. Set mixture to cut-off. Now you know you are not going to be adding more fuel.
3. Open the throttle wide. Now you know you are going to be adding a lot of air.
4. Hand on throttle, crank the starter until the engine fires. The cranking engine draws in air and exhausts the over-rich mixture, weakening the mixture until it reaches the right level.
5. Immediately but smoothly bring back the throttle to a little above idle (1/4" in most aircraft for starting) then mixture up to rich, but don't hurry either action.
I have had a backfire using this procedure, but that was because there was something wrong (can't remember what - might have been a cracked exhaust as that a/c had a few) and did no damage itself; it should not happen. Starts often put fuel in the exhausts, and shouldn't cause a backfire.