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I Busted It?.

Ironflight

VAF Moderator / Line Boy
Mentor
In the nanosecond between when my mind realized what my fingers were about to do and when the muscles contracted, there wasn?t time to put out a ?Don?t Do it!? order on the neural net?.and the next sound we heard in Mikey?s cockpit was this horrible ?clang?.whirrrr??? Yup ? pilot-induced kickback! It was my leg to fly after a fuel stop on our way to an airpark fly-out, and it was one of those hot starts where it cranked a few blades, fired, then didn?t, so I let off?and just as I was going to try again, it fired again ? and the six-year-old Flyweight didn?t have a chance. After some inappropriate language on my part, I climbed out and went around front to give a tap on the cowling ? and the starter "tapped" back ? it was definitely loose underneath there. It was pretty ugly - but at least it was a clean break!

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Fortunately, we had the necessary tools to pull the cowling there on the ramp, and sure enough, we had a free-hanging starter. Also fortunately, Mikey usually starts really well, especially when warm, so we pulled the remains of the starter, taped up the ends of the cable, re-cowled, and hand-propped for the trip to lunch and then home.

Now despite the fact that I have several thousand hours with the Sky-Tec Flyweights without any failures (up until now), the company has done a lot of work in the past decade at improving their products, and our latest Mattituck engine came with their newer NL style starter ? which has a shear pin in the drive. I personally think it is nice to have something that will shear before the housing, and here was a chance to upgrade on the cheap, so I just got off the phone with the folks in Granbury, and they are sending out a new NL in trade for the broken LS that I can ship back (along with a credit card number for the $54 price difference, and my share of the repair bill of course). Mikey should be ready to go in two days, and that only leaves the Valkyrie with her original LS starter ? which is working just great!

Paul
 
I love the pictures. We all do silly things sometimes :). I'm fixin' to post my series of pictures of how one simple ignored chipped tooth in a ring gear can cost $300 (two for the starter and one for a new ring gear).
 
Bummer. I have done the exact same thing and got away with it with no damage. I will try to be disciplined and remove my hand from the switch as soon as she catches. It is just too easy to do this.
 
Is the real problem here Lycoming's use of only one impulse/retard mag? So as the key goes back to both the non retard mag fires early and causes the kickback? Would having two impulse mags fix this? Or even using independent Mag switches instead of the key switch?
 
It would be nice is Van's supplied the NL instead of the LS.

I was able to get a good deal to swap my un-used LS for a NL.

The NL does come with extra pins glued to the case, just in case you shear one away from home.
 
Nominal wt. Diff

The weight difference between the Standard and LS is .8 lb. However, the website says ALL are equipped with a Kickback Protection System.

If I have a problem with my LS I'm going to go with the NL. Not worth potential issues.
 
Is the real problem here Lycoming's use of only one impulse/retard mag? So as the key goes back to both the non retard mag fires early and causes the kickback? Would having two impulse mags fix this? Or even using independent Mag switches instead of the key switch?

Not sure....might be....this is the only airplane we have with a key switch - our others have separate ignition and start switches.
 
Not sure....might be....this is the only airplane we have with a key switch - our others have separate ignition and start switches.

After replacing a starter for the very same reason (Sky-Tec, no charge), I start mine like a radial, engage starter, count 3 blades, turn on a mag (one impulse, one lightspeed, either one will do the job).

It is working for me so far.
 
OTOH

Bummer. I have done the exact same thing and got away with it with no damage. I will try to be disciplined and remove my hand from the switch as soon as she catches. It is just too easy to do this.

Hmmmm. I thought it was better to keep the key switch in the crank position for a couple of seconds after the engine starts. The theory is: by continuing to crank, the right mag is grounded, and can't fire, which allows the left mag with its delayed spark start the engine. Then when you release the key switch, the right mag kicks in.

If you release the key switch too soon, when the engine RPM is too low, the right mag can fire at 25 degrees BTC and cause kick-back.

Engine Gurus chime in please.
 
What I enjoy the most about the above pics...is the oily residue! Makes me feel a tad better about my "mystery" oil seepage towards the rear of the engine. :D
 
What I enjoy the most about the above pics...is the oily residue! Makes me feel a tad better about my "mystery" oil seepage towards the rear of the engine. :D

Hey, Mikey WORKS for a livin' - nothing fancy about him! :D

Besides, any Lycoming "of a certain age" is going to seep a little bit - if it doesn't it means you're out of oil....;)
 
NL v Flyweight

Thats the reason I put a NL on my O320E3D. My buddy with two electronic ignitions went thru 3 starters befor resolving the ignition problem. I am sure his problem was ignition timing related and not really the fault of the starter.
 
just curious how many hours on the mags? do you have mags? could a kick back be caused by mags in need of overhaul. :)
 
just curious how many hours on the mags? do you have mags? could a kick back be caused by mags in need of overhaul. :)

Nahh....this was completely me stuttering on the key switch. The mags wre recently checked and timed.
 
Hmmmm. I thought it was better to keep the key switch in the crank position for a couple of seconds after the engine starts. The theory is: by continuing to crank, the right mag is grounded, and can't fire, which allows the left mag with its delayed spark start the engine. Then when you release the key switch, the right mag kicks in.

If you release the key switch too soon, when the engine RPM is too low, the right mag can fire at 25 degrees BTC and cause kick-back.

Engine Gurus chime in please.

Hmmm, I obviously misunderstood the sequence of events.
Paul - can you expand on what exactly you did that you feel caused the kickback while the starter was still engaged?
 
Kick Back

Paul,
I feel your pain. Before installing the wonderful P-Mags, I had LASAR mags on the Doll. I learned that you could not get every month out of that expensive aircraft battery that you could if flying with standard mags. During starter engagement, with the battery past its prime, the buss voltage would drop below the voltage required by the LASAR computer. The computer would simply drop out making the ignition revert to standard magneto operation. Of course the mags did not have impulse units on them, and the timing would jump from TDC to 20 degrees BTDC. The result was an immediate kick back causing starter damage.

I never broke one clean off the engine like you, but I did remold the front case to a slightly different fit! $$$$$$ It would have been cheaper to purchase a new battery well before battery failure.
 
Hmmm, I obviously misunderstood the sequence of events.
Paul - can you expand on what exactly you did that you feel caused the kickback while the starter was still engaged?

Basically, I thought the engine had caught, let off slightly on the switch, my senses said it didn't fire on the next prop blade, and my fingers twitched it back to start (to try and catch it? I don't know it was dumb), and then it fired again - possibly the right mag fired early - don't know. It was just a dumb reflex kind of thing, not enough time for conscious thought.

Was it truly a "kickback" in the traditional sense? Not sure I can tell you at this point, but "don't try to engage a starter when the prop is moving" would be a good rule of thumb...:eek:
 
Basically, I thought the engine had caught, let off slightly on the switch, my senses said it didn't fire on the next prop blade, and my fingers twitched it back to start (to try and catch it? I don't know it was dumb), and then it fired again - possibly the right mag fired early - don't know. It was just a dumb reflex kind of thing, not enough time for conscious thought.

Did exactly the same thing a few months ago. Good news is the NL's shear pin works as advertised.

Look at the bright side. Not many guys can claim to be strong enough to break a starter with just one finger ;)
 
Here is my version of the same event. About a year ago, I did much like Paul. I hit the starter and it didn't fire on the second blade as it usually does. I released the starter for just a moment and for some silly reason just didn't wait for the prop to stop before my finger inexplicably hit the button again. No kickback, just stupid human tricks. I have an NL starter and the shear pin didn't shear or anything too bad happen except for the blood drawn from the lightning bolts of shame coming from my copilot's eyes. We flew as happy campers.

At my next oil change I noticed a chipped tooth on the ring gear. Yeah, ****, I sure know exactly when that happened. I inspected the starter and its gear and all was well.

chipped%2520ring%2520gear.JPG


We flew for about a year with that chipped tooth on the ring gear until I recently noticed a very closely matching starter gear failure. Bummer. Uncle!

starter%2520tooth.JPG


What to do? Well, fix it of course. I just so happened to have an exact brand new replacement starter in the shop that is going on the next project so we did a direct swap. Old starter off, new starter on.

old-new_starter.JPG


The old starter went back to Skytec to be fixed and was promptly returned with a full overhaul for $250. Ouch. We ordered a new ring gear $100 and began what Tanya still considers nothing short of a magic trick.

I cut the old ring gear off of the flywheel. Much easier said than done. First I hit it with a hack saw. Yeah right, it laughed at me without a scratch. Then I walked over to the metal cutting band saw and got the same results. Nuttin'. Finally I mounted it up on the milling machine and made headway after destroying three of my bulk stock of cheap Chinese mills for just such projects. Whacked it with a cold chisel and it popped off.

ring%2520gear%2520off.JPG


Next up the necked flywheel went in the freezer (It didn't eat the fruit bars while in there.) and the new ring gear in the oven.

freezer.JPG


oven.JPG


Ta Da! Like magic, it drops right on and instantly is one with its new home.
together1.JPG


With the airplane all put back together with all the teeth in the right place, I was amused at how impressed Tanya was that it didn't spin right off of the flywheel the first, and second, time that we hit the starter. I think the next time I chip a ring gear, I'll just replace it first.

Thanks Paul for starting the conversation.
 
Am I the only one here impressed that he hand propped a 360?!? :D

Can't be any harder than hand propping an 0320 with the prestolite starter engaged..........:eek:


PS. You can cut off the ring gear with the same wheel and die grinder that cut your canopy.
 
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Drilling a hole in the ring gear followed by a good smack with a cold chisel works as well.

Please don't ask how I know.
 
Am I the only one here impressed that he hand propped a 360?!? :D

Mikey has been hand-propped on four occasions (that I know about) by three different guys. Three of the times, it took multiple tries but finally caught. When the engine was warm last Sunday, I think it caught the first or second try.
 
Am I the only one here impressed that he hand propped a 360?!? :D

An O-360 on a taildragger isn't hard to prop at all. I have operated for periods of time that way when the starter was in for repair. Personally I wouldn't try to prop something like a C-182. Actually I have probably tried to do that in the past with poor results.

High compression and tricycle gear and three bladed props and lots of cylinders are some of the things that scare me.
 
I'm definitely impressed. I'm going to have to get much older and bolder to be one to jump out there and give that a try.

I'm thinking about how hard it would be to throw the prop over on a motor that big. Guess it's not though?
 
Try hand propping an IO-520 on a Cessna 206 with a 3 blade prop.

Now that got my complete and utter attention..........

Yes, it worked but there is no way I want to repeat it.

p.s.

I was 23, a Skydiver Pilot and totally dumb :D
 
Try hand propping an IO-520 on a Cessna 206 with a 3 blade prop.

Now that got my complete and utter attention..........

Yes, it worked but there is no way I want to repeat it.

I was 23, a Skydiver Pilot and totally dumb :D

Now that sounds familiar, only substitute a Baron 58 (IO-520, 3 blade) for the 206... I was also 23 and a fearless (dumb!) freight dog.

BTW, it was just about the easiest hand prop I've done, but I think that was just luck.
 
This would get really "interesting" if somehow as the ropes and tip cuffs get slung out radially, they then get sucked into the prop. And the guys holding the rope get their ankles caught in the rope. It would be a sequence for Indiana Jones or James Bond:eek:

Our friend Tom Navar of El Paso tells of this exact thing being done to a DC-3 in Mexico...but with a mule!!
 
Mag Switch Wiring

Hey everyone, if you are using a key type mag/start switch and you have left impulse and right non-impulse mags you should have a jumper on the back of the switch between the "R" teminal and the "GRD" terminal to keep the right mag P-lead grounded while in the start position.(the GRD term. is right next to the R term on the back of the switch) The non-impulse mag can still fire even when just cranking especially if the mag is strong and you are using these modern higher rpm starters...just sayin'
 
Hey everyone, if you are using a key type mag/start switch and you have left impulse and right non-impulse mags you should have a jumper on the back of the switch between the "R" teminal and the "GRD" terminal to keep the right mag P-lead grounded while in the start position.(the GRD term. is right next to the R term on the back of the switch) The non-impulse mag can still fire even when just cranking especially if the mag is strong and you are using these modern higher rpm starters...just sayin'

Of course.

And if you are hand-propping, put the key in the "left" position, not the 'both' position. That way, you are starting on the impulse-coupled mag.

And if you don't have mags, and your battery is below 6 volts, watch out and think about what you are doing. As in the other thread ongoing about hand propping.
 
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