Cold Starts

[jdlowrey]

When I purchased my aircraft (1940 BC-65) last spring, the previous owner instructed me to turn the prop a few times before attempting to start to work fuel and oil into the cylinders. Subsequently I have been doing this on every cold start. Recently though I went through this procedure then hand propped the plane, after running the engine a good 10 minutes so I went to shut off the mags to shut down the engine and to my surprise the engine continued running. In order to shut it off I had to turn the fuel off. I had the grounds tested on the mags and they checked out ok. The weather has been reasonably warm here until recently ( in the 30's) and a storm went through the week before with lots of blowing snow which I'm guessing may have been a factor in the ignition switch not functioning properly.

What concerns me most is that I am standing in front of my plane turning a prop while unbeknownst to me the mags are hot. I have grown rather fond of my appendages and am reluctant to lose them which leads me to my question. Is turning the prop a few times before attempting to start really necessary? And by not doing so am I damaging the engine?

Thanks for any input,

Jeff

[jgerard]

Re: Cold Starts

I always prop from behind.

Jason
N43643

[Carl Ellis]

Re: Cold Starts

Jeff -

Many people will handprop these smaller engines by standing by the right door. You will be behind the prop and will have ready access to the throttle and switch.

- Carl -

[jdlowrey]

Re: Cold Starts

I prop from behind by the right door as well but what I was wondering, before I go to prop start, I turn the prop a couple of times, with the ignition switch off. The purpose of this is not to start but I guess to lubricate. As the intent is not to start, the prop is slowly turned which is best down from the front. Wondering if I can skip this step?

Jeff

[robbie]

Re: Cold Starts

When you hand prop the engine , allways treat the engine as it hot.
My started on me day as I was pulling it through.
When I'm proping now, each blade is treated as a hot prop.
You need 3 or 4 blades to get the gas to the cly. before its going to start for you

[Robert Lees]

Re: Cold Starts

Jeff, if the mags ground OK then it is the switch. They are not impervious to grounding failures.

Get it checked out, or do it yourself: Can I assume you have a switch like the one on this thread. If so, the contacts can sometimes be shorted by the use of inappropriate connection at the back of the switch (or a loose piece of metal, as was my case).

Jason and Carl: are you sure you always pull through from behind the prop?

Rob

[Dick Smith]

Re: Cold Starts/hot mags

Jeff, my thought is to "never", "ever" touch that prop without forethought...as what you mentioned about the mags being "hot" when you thought they would respond to movement of the ignition switch to the "off" position...shows that "control" of that prop (or "machete") is subject to mechanical or electrical glitches that can and will kill or maim you. I had an impulse mag perform it's designed function once, when I moved the prop about 2 inches, slowly, listening to the movement of the internals, when a faulty P-lead connection allowed the engine to fire and turn one or two revolutions. It caught me offguard and could have killed me or chopped something off. Now I prop from behind almost exclusively...I want to be behind that "meat cleaver" and close to the mag switch and throttle...and any moving of the prop gets some thought as to my position, footing, traction, cockpit control settings and planned movement, "when", "if" or "however" the engine starts. In any case, I don't usually "wind the prop" several times. Rather, I'll give it 2 1/2 or 3 shots of prime...pull it through 7 or 8 times(listening and feeling...for the impulse "clicks", compression and lack of "stiffness"(having preheated), then mags on "both", yell "clear"...really look around...she'll start first pull... (sometimes, I'll have the primer unlocked and ready for quick, short "helper" bursts of fuel to get past stumbling of the engine, but it's usually not necessary) Preheating or keeping the engine wrapped with the cowl cover after shutdown goes a long way toward providing easier starting. For what it's worth.
Some of the other folks on the list can surely jump in with further comments re: the safety aspects of shutting down with mixture control or fuel valve, verifying mag switch functions after starting and before shutting down, etc. As quiet as it's been, there has to have been some "deep thought" going on out there! Dick

[jrzangger]

Re: Cold Starts

Starting from behind is certainly acceptable on an engine with impulse couplings. It doesn't take much movement to fire. However, without impulse couplings it is necessary to give quite a healthy pull to provide a "hot" spark. In over 40 years of propping Taylorcrafts, I have always propped from the front. Most always pull it through quite a few blades and in colder weather will pre-heat and use a couple of shots of prime.

The prop always must be "Hot" in your mind and be treated as such. If this is heeded there shouldn't be any unnecesary risk involved as long as the throttle isn't "cracked" excessively. I rarely put much more than a slow idle setting in and always have the plane chocked or tied.

When propping I've seen many people mistakenly stand uncomfortably far from the prop and then lean forward into it. This can actually cause you to lose balance and fall towards the prop. I generally stand quite close to the prop and use the energy from the propping motion to allow my body to move away from the prop as it's swung.

There are many styles and techniques used and some are safer than others. Use your best judgement and stay clear of the moving prop!

[NC95842]

Re: Cold Starts

The reason the motor kept running after you turned the mags off is because the carbon deposits on the top of the piston/head were glowing hot.

If this happens again turn the mags back on and give it a little run up, pull back to idle and turn the mags off.

My plane does the anytime I let it idle for a long time. Maybe its because I like to run auto gas with a lot of carbon in it. Or it could be because auto fuel has a low “anti knock” (pre-ignition) number.

When the eng is breathing cool air it is getting a more dense charge. That also contributes to pre-ignition.

When the eng. has been shout down for a few minuets all the hot carbon has cooled. Then we can swing the prop with a steady hand.

But we should always act as if the prop is hot.

[matsuthunder200]

Re: Cold Starts

I seen a guy handprop a supercub one time. It started and the throttle was wide open. He was in front of it he did manage to jump out of the way but the cub took off down the taxiway and hit a frinds 180 at about 30 miles an hour it wiped out the supercub and did about 30,000 damage to the 180. I always start mine from behind on the right side. I have started it with the throttle cracked open a little to much and it was very easy to reach inside and pull the throttle back. With the plane on floats i haft to stand on the right side and behind the prop with the door open. I got so ust to doing it that way that i do it that way on wheels and skes also. The otherthing that i think is important is if you do prop from the rear always walk around the tail of the aircraft to get in. We lost a good frind in kenai he walked right into the prop after he started it.... Pime 3 times cold, mags off, pull thrue 4 or 5 times, mags on pull stars every time first pull well most of the time..........

[jgerard]

Re: Cold Starts

My primer system is squirts in to each cylinder instead of the intake spider. One shot of primer and she is ready to go!

My 46' ship has sliding windows on both sides, so when starting I keep the left hand on the fwd window frame and use my right to swing the prop. I also push the prop up ( backwards) to kinda bounce it off the cylinder compression and help get a full stroke when pulling it through.

It seems to start on the first or second pull. I stick my head in the window to check oil pressure, select "both" on the mag switch, then I wait for the idle to stablize before walking around the TAIL to pull the chocks and get in the plane.

Jason
N43643

[Len Petterson]

Re: Cold Starts

Starting the engine from behind. I have tryed it, but can't get enough swing on the prop for her to start.
A friend of mine starts his what way with the rigth door open.
I have made a quick realise hook with a rope to a tiedown and the rear handel on the fuselage. I think I will make someting to attach to the tail wheel bolt for it. As it is not always possible to use it as there maybe nothing to tie it to. Then I use parking brake and chocks.
My parking brake is holding good but is not reliable if I pull to hard on it.
The plane will not move untill about 1300 rpm with the brake set.
I use a set of shocks with pull string on, They are working well for me.
I open and close the trottel before starting and lock the trottel all the way out! My trottel has to be all the way out for idle. (=500 rpm static)
Earlyer in the year I described the quick reliese hook in the forum.
It was found in a older EAA sport aviation, it is a Tony Bingelis invention.

In my short time in aviation I run across 1 faulty ignition switch.
A fixed contact had broken away from it's mounting and the starter contact did not work. ( in a homebuilt, the original builder had purchased a used part.) The result was no starter and possibly a intermitent hot mag.
The broken part was laying loose inside the switch.
Remove it and check it with good test ligth and Ohm meter.
Mine was replaced about 100 hr and 10 years ago. Yes, it will be checked out then I am replacing my P leads and plugs shortly.

My instructor said: Always consider a Mag hot then moving a prop!

I like say Thank you to all of member off Taylorcraft.org and Webmasters for the help I resived from evrybody during the past year.
It been rewarding for me to be able to give a little something back as well.

With what, I wich you all a God Jul.
(Swedish for Merrry Cristmas) from me and CF KZU.
Len Petterson

[btbell]

Re: Cold Starts

I think that those who have said to always treat the mags as hot are absoutely correct. I prop from the front usually when I have someone else at the controls. I will usually prop from behind when I am alone and always with the wheels chocked and tail tied down.

Whenever I tough the prop either to start the engine or to inspect it for nicks, I ensure the ignition switch is OFF and when I move the prop, I always do it in a fashion that if it would start, my hands would be clear. I always pull my enging through 6-10 times to prime the cylinders before cold starting and follow the same procedure as if I were proping it.

Many people have different ways of starting their engines and they are all right as long as we think safety first.

[jdlowrey]

Re: Cold Starts

Thanks for all the good advice. I'll check the ignition switch and review my start up procedures. Safety first.

Happy Holidays

Jeff Lowrey