The FAA has different categories of aircraft. What category your aircraft falls under decides all sorts of things including what work a non-mechanic can do and what parts are and aren’t allowed. The IAR-823 is classified as an experimental exhibition plane.
I will be mentioning getting various parts from non-aviation sources and other things that would not work with certified airplanes. We are being very careful to do this SAFELY. Manuals are being used extensively and we are asking for help from people who specialize in their fields. Tolerances, strength requirements, and material interactions are just of few of the things kept in mind at all times. I am checking with an A&P on anything that has the slightest bit to do with the structure and we will be having them sign off each step of the way. I’m doing my best to keep everything well documented and most of what you see here has been run by at least one (and usually several) people experienced with airplanes.
Safety is our number one goal in this project at all times. It will take us longer and cost more money, but we will be doing this right.
One of the things we were most worried about as we looked at starting this restoration is how we could replace the bolts that held the wings on since they had been lost in California. We lucked out when Steve Stavrakakis had a spare he was willing to loan us and we found a machine shop that does quality work and isn’t afraid to make things for aviation use.
At first glance, this looks like it shouldn’t be too difficult to find. It looks to be just another shoulder bolt drilled for a cotter pin. Nope! We were able to use the manual to find that the tolerances are tiny. Just 1/1000 of an inch can be the difference between the bolt working as intended and wearing in an unsafe way. They also have to fit the holes in the attach fitting. Not easy to find and doing it wrong could mean the wings falling off in flight.
I spent time talking with Glenn at Limited Productions in Bellevue, WA and showing him this bolt along with the manual. We were able to find the specs for the material in the manual and it matched 4140H. Glenn compared the strength properties of that to the strength requirements called out in the manual to be extra sure it would hold. All we needed to do was provide him the dimensions needed.
How do you measure a hole to 0.001″ accuracy? You try the micrometer that works great for most of what we are doing and notice that you can’t get the same number twice and then you decide you need to find the right tool for the job. After all, the wings need to stay where they are supposed to! There are lots of options for inside micrometers out there and they get more expensive as you get more accurate. We decided that a two point option with 0.0001″ accuracy was plenty for what we are doing.
This thing is awesome. It comes with a disc so you can check the calibration. It does need to be calibrated once per year to ensure it stays within tolerances, but I can live with that. This thing even specifies what temperature it was calibrated in. I ordered from MSC Industrial Direct and would happily buy from them again. Here is a link to this one: https://www.mscdirect.com/product/details/38170874?rItem=38170874
Being able to measure helped. We also discovered that the holes in the attach fitting are not perfectly round. Great. We will be honing the holes to precisely match the custom made bolts. I’ll post on that as we actually do the work and I can give pictures and information other than what we plan. (Since things on this project seldom go exactly as planned!) The general idea is that we will hone the holes out to fit the brand new bolts. then hold them in place with unthreaded bolts (essentially pins) that Glenn also made for us while we carefully place each bolt.
I’m sure you noticed that one is pretty and shiny while the other is dull and sort of yellow. That is because the pins were left as Glenn made them and the bolts just came back from being cadmium plated to prevent corrosion. The dull finish is because they had to be baked as part of the plating process since they are hardened steel. The team at Metal Tech in Monroe, WA were great to work with. I dropped these bolts off to them on a Tuesday and was able to pick up that same Friday. They also took great care tagging each bolt and returning them to their correct bags so that we can identify them. (We do have that cool inside micrometer but I still don’t want to have to sit and decide with 100% certainty exactly which bolt is which since some are just 0.002″ or less difference in size.) Link to Metal Tech: https://metaltechfinish.com/
One thing the pictures don’t show is that Glenn made the awesome suggestion that the threaded part of each bolt be made to a standard size. Brilliant! the part of the shank that goes through the hole is exactly the size of the hole in the fitting (well, what we will hone it to be) but the threaded section is just a tiny bit smaller so that it works with AN standard nuts and washers that I can just buy off the shelf at Spencer Aviation. He also made the head a standard size so they work perfectly with our tools!
I’ll be mentioning Glenn often in this blog. He and his wife are nice people who run their company machining pieces to exact specifications. He knows what he is doing and is genuinely a pleasure to work with. http://limitedproductions.net/5001.html
The handles are a mostly superficial piece, but they had to come off when we removed the glass for replacement. The hinges are from the canopy doors and looked grungy enough we wanted to remove them and make sure they are still okay for use. It seems like a great opportunity to clean them up and make them look nice.
We’ve spent a lot of time with brass brushes and WD-40 and it has gotten a bit old. Bruce decided to look for better options to try out that will clean the metal up and not cause damage. What he found as the most promising looking option is used on car restorations. Eastwood has some great demos showing how well it works so we decided to give it a try.
Here is what we ended up with after soaking the pieces (plus a few odd bolts and washers) overnight:
Here is what we ended up with after just minimal wiping with a paper towel:
Not bad! It definitely beats trying to scrub all that rust off and is much better for the parts. I’ll be taking these in to a shop for fresh chrome plating before they go back on.
Bruce took the wheels apart so we can do a dye penetrant test to ensure the wheels are still in good shape. Since another IAR had a problem recently, we want to be sure to fully inspect everything! There will be more posts detailing other areas, but the wheel bearings are an interesting piece that deserve a post of their own.
We wouldn’t have thought much of what we found except that we read up on what to look for when inspecting bearings. We found grayish black streaks on the bearing cups in the wheels that matched the spacing of the rollers.
This was our hint that we need new wheel bearings. Those marks indicate that water had been in the bearings. This is one of the best guides to inspecting bearings that we have found. It includes pictures of what to look for and what it means when you see certain signs. I will definitely be browsing their other topics as we go through this restoration and highly recommend them: http://www.flight-mechanic.com/aircraft-wheels-wheel-inspection-part-two/
Knowing we needed to replace is a great start. Where do you go to find them? It is difficult (and expensive) if you are buying bearings for an airplane but if you are looking for bearings for your race car… I was able to take one of our bearings in and have them match exactly what we have. It isn’t anything uncommon so you can take the product information and just buy one.
Original bearing is on the left and the new one is on the right.
Timken X30208M The new ones ran about $35 each and came with bearing cups.
Number 4 came from the Romanian Air Force to the United States through an importer in Vermont. Bruce picked it up himself and flew it to his home in California. He enjoyed flying it for 200 hours then took it in for an annual with his mechanic. It needed a few basic maintenance items, but was in good shape.
The mechanic took some parts off for work then found himself in the middle of an ugly divorce. We’re not entirely clear on why it was as dismantled as it was, but there it was. During this process, the mechanic lost various pieces including the wing attach bolts. As luck would have it, Bruce had already started the process of moving here to Washington and couldn’t figure out how to deal with the airplane at the same time as having health issues and caring for a new baby. A friend in California was able to get it moved to his property so it wasn’t in danger from the mechanic’s divorce, but no one knew how to proceed given the lost parts.
I came into the picture several years later. We were able to arrange transportation from California to Harvey Airfield in Snohomish, WA. That took what money we had available for a bit. Shipping something of this size is no small thing!
IAR-823 number four has been sitting for too long. It is time for us to get flying again. I will be using this blog to document the complete restoration project and all of our flying adventures that follow. Feel free to comment and ask questions along the way. Our goal is to document every step so that other owners can use the information gained from the process.
IAR-823 number 4 