maintenance matters Did a kickback knock your teeth out? Despite the best efforts of amateur a bunch of money replacing good parts, The first step in the process is to buy a builders, a kickback on the first engine we will take a look at replacing just the new ring gear. There are two choices, as start is more common than you might ring gear. To get an idea of the dollars mentioned before, so you need to know think. The damage is usually seen in two involved, my local engine shop, Corona if you have a 122-tooth or a 149-tooth places—the starter main body casting Aircraft Engines, offered to sell me a ring gear. Trying to start an engine with gets broken or bent, or the starter ring new ring gear for $200 and install it for a 149-tooth ring gear and a 122-tooth gear gets a few teeth knocked off. Either an extra $50. I found one online for $177, starter motor will have you going back to way, you have a repair job to deal with but I would have to add shipping to that, the parts store to say goodbye to even before you are going to get your engine so $200 looks like a fair price. I searched more of your hard-earned money. Check running. Of course, a starter kickback for the complete ring gear and carrier the model number of your starter and can happen at any time during the life assembly and found one on eBay for count the teeth on your ring gear twice. of an engine, but first startup seems to $625. After that I didn’t even want to see No need to add to your frustration by be the most likely time to have a prob- what a new one from Lycoming would mismatching parts. lem. Another way to wreck your starter cost. With those numbers in mind, it With a new ring gear in hand, it is time ring gear is to mismatch the teeth on looks like we can rule out buying a com- to remove the old ring gear from the - the starter and the ring gear. This can plete ring gear/carrier assembly. We are rier. Needless to say, this means remov- happen because Lycoming engines still left with the option of paying the ing the propeller and the ring gear carrier come with either a 122-tooth ring gear engine shop $50, but it isn’t that hard to assembly from the plane. Using a Dremel or a 149-tooth ring gear. The starter gear do the work yourself, so let’s get to it. tool or an abrasive cutoff wheel of some must match the tooth pitch or disaster will follow. If the starter is damaged, your best bet is to simply remove it and send it back to the manufacturer for repair. Especially if your starter is new, this makes much more sense than buying a new starter and saves about half the cost. The good news is that the latest versions of light- weight starters are less vulnerable to kickback damage. If your starter is fine, but you have bro- ken a few teeth off the starter ring gear, that thing some people call the , you have two choices. You can buy a new carrier with the ring gear installed, or you can replace the ring gear yourself. Multiple severe kickbacks really made a mess of this ring gear. A successful engine start Since there is no good reason to spend will have to wait for a replacement and a careful examination of the timing and wiring.

Dave Prizio is a Southern California native who has been plying the skies of the L.A. basin and beyond since 1973. Born into a family of builders, it was only natural that he would make his living as a contractor and spend his leisure time building airplanes. He has so far completed three—a GlaStar, a Glasair Sportsman, and a Texas Sport Cub—and he is helping a friend Dave Prizio build a fourth, an RV-8. When he isn’t building something, he likes to share his love of aviation with others by flying Young Eagles or volunteering as an EAA Technical Counselor. He is also a member of the EAA Homebuilt Aircraft Council.

50 KITPLANES January 2015 www.kitplanes.com & www.facebook.com/kitplanes Use a Dremel tool or cutoff wheel to cut the old ring gear. Cut as deep as possible with- Use a hammer and cold chisel to break out cutting into the aluminum carrier. the ring gear at the cut you just made. sort, carefully cut into the steel ring gear heavier hammer rather than a lighter You will need a medium-sized hammer as far as you can without touching the one, and don’t forget to wear safety and a pair of pliers or hot pads for carry- aluminum carrier. The front side of the glasses. It will eventually work, and the ing the heated ring gear. carrier has a flange that can be damaged ring gear will come off. When sufficient time has passed, get if you try to cut the front side as deeply The bare carrier should now be placed the carrier out of the freezer and place it as the back side. Go slowly. Check often. in your freezer for 20 to 30 minutes. While on the blocks on your workbench. Dou- Do not get impatient. Do not cut into you are doing this, you need to put the ble check to see that the mating surface the carrier. new ring gear in your oven for a similar is perfectly clean. Now the moment of When you have cut the old ring gear amount of time at about 450°. The cham- truth. Retrieve the hot ring gear with the as far as you dare, get a cold chisel and fers leading into the gear teeth should be side that has the chamfered cuts leading a hammer. This is one of the very few on the side facing up, so it will be ready into the gear teeth facing up. (It should times when a big hammer is the proper to place on the carrier. This will shrink the have already been placed in the oven tool. Place the cold chisel so it will cut carrier and expand the ring gear enough that way.) If the chamfered cuts end into the edge of the ring gear at the to overcome the interference fit that the up on the front side, your starter will point where you have already cut it, and parts have at room temperature. While not properly engage into the ring gear give it several good whacks. With luck you are waiting, be sure to prepare your teeth. That means that you will have to the ring gear will snap open and fall off work area for the mating of your parts, cut off your new ring gear and start the the carrier. If it does not, you may need and make sure you have a clear path whole process over. to work up the courage to cut the ring from your oven to the work area. Place Quickly but carefully carry the ring gear gear some more, again working slowly two blocks of wood to support the edges over to the carrier and drop it into place. A and carefully. It is also better to use a of the ring gear and get your tools ready. few taps of your hammer should help to

The new ring gear is ready to replace the damaged gear on the ring gear carrier assembly. Make sure the new ring gear is perfectly clean The ring gear should snap open after you break through the before heating it up. Any remaining residue on the ring gear will cut with your hammer and chisel. really make a bad smell in your oven.

Photos: Dave Prizio and John Harrell KITPLANES January 2015 51 Use some pliers or hot pads to handle the ring gear after getting Quickly tap the ring gear into place and be sure it is seated it out of the 450° oven. Work quickly but carefully. There is no against the flange at all points. second chance to get the ring gear on properly. set it firmly against the flange. It is all over the wrong orientation, but you will have likely culprit is improper ignition tim- in a few seconds. Double check around no way to set the timing of your engine ing, but there are some other poten- the perimeter of the gear to make sure it in the future. Be sure to check this out tial causes, especially when dealing is fully seated into position. With the new before you install the prop. with a first engine start. In any case gear in place let the assembly cool for a The propeller can be installed once check your ignition timing before few minutes before you move it. the ring gear assembly is in place. Con- doing anything else. Now that you have a new ring gear, sult your propeller manufacturer for Your ignition switch could be ground- it’s time to put it back on your plane. proper installation instructions includ- ing out the wrong , or it could Be sure to line up the “0” on the carrier ing proper torque for prop bolts. Be sure not be grounding either magneto. Stan- with the similar mark on the that you have positioned the dard practice dictates that the right flange. You can double check by moving before you bolt on the prop. There magneto is grounded out, so the left #1 to top dead center and verify- is no way to get the belt on without magneto—the one with the impulse ing that the “TC” mark on the carrier lines removing the prop if you forget. Set the coupling—can start the engine with up with the timing hole in the starter belt tension after the prop is installed. the timing retarded to top dead center on the front side or the case split on the Now that everything is back together, instead of the typical 20 to 25 degrees. back side. The engine will start and run the task of figuring out why the engine Check your wiring to make sure this is just fine if the carrier is installed with kicked back presents itself. The most properly configured. If you have the standard ACS ignition switch, be sure that the jumper is installed between the R terminal and the adjacent GND termi- nal. If you have electronic ignition, be sure to go over the installation of your ignition components and follow the manufacturer’s recommendations for setting the timing properly. Poor technique can sometimes be the culprit. Be sure to firmly engage the starter switch and do not release pressure until you are finished cranking. Some- times people will be rather tentative when engaging the starter and will allow it to momentarily stop cranking and then re-engage. This is an open invitation to starter trouble. This same problem of tentative or intermittent engagement When reinstalling the ring gear assembly, be sure to line up the “0” on the carrier with the can be traced to problems with the mark on the crankshaft flange. starter circuit wiring or the starter relay.

52 KITPLANES January 2015 www.kitplanes.com & www.facebook.com/kitplanes JUMPER Use when left mag is Retard Breaker mag or has impulse R coupling L

GND UR

S GND

BO 4

BAT

If you have the standard ACS ignition switch and are using two , be sure to install the jumper between the R terminal and the adjacent GND terminal. This way the right magneto gets grounded out when starting. Consult the manufacturer of any electronic for their installation instructions.

Any poor contact in the relay or the cir- Sky-Tec makes the HT-series of starters cuit could cause poor starter engage- with built-in kickback protection. This ment and a possible kickback. feature will add about $50 of extra cost Lightweight, or what some people call and 10 oz. of weight compared to one of low-inertia, propellers are a secondary their standard LS-series starters. Hartzell contributor to kickback problems. They also has a starter line with kickback pro- do not directly cause kickbacks, but tection called the E-Drive series. their low inertia does not put up much Of course, ring gears do sometimes resistance to a kickback. There is no sug- need to be replaced because they sim- gestion here to avoid these props. Just ply wear out. Lycoming Service Instruc- be aware of the heightened need to be tion 1141A specifically addresses this careful about avoiding things that could issue and includes basic information for cause a kickback if you use a lightweight removing and reinstalling the ring gear. wood or composite prop. We hope that you can enjoy your plane Proper timing, proper wiring, and long enough to wear out a ring gear. But good technique should eliminate starter for new builders facing their first engine kickbacks entirely, but if you are still start, please make sure you have done concerned, there are starters designed what you can to avoid a damaging kick- specifically to reduce kickback damage. back at initial start-up. J

Manufacturer Model Series Weight Cost

Hartzell X-Drive 7.6 lbs. $398

Hartzell E-Drive with kickback protection 9.5 lbs. $433

Sky-Tec LS-series 8.25 lbs. $380

Sky-Tec HT-series with kickback protection 8.9 lbs. $431

KITPLANES January 2015 53