Tip Posted January 26, 2020 Report Share Posted January 26, 2020 I would probably order a new one. Quote Link to comment Share on other sites More sharing options...
ibjet Posted January 26, 2020 Author Report Share Posted January 26, 2020 Aircraft grade steel tubing is what's called High Strength Low Alloy, or Chrome Moly, or 4130. For weldments it is furnished in condition N (normalized). It is heated up to about 1100/1200 degrees at the weld locations during welding. When done in a factory setting it is stress relieved after welding or forming. That is what I will be doing is a stress relieve. I emailed Arian yesterday, I'm sure he won't see it until Monday. I described my process to him in detail. I was planning to turn off the lights in my garage when I do the heating so that I can see when the mount just begins to glow red. I saw on Amazon that they have infrared thermometer guns for under $20. BTW: I decided I would need to heat the weldment to avoid over stressing it. It is very springy and when cold straightened you have to over bend it quite a bit to get the shape you want. By the repeated bend, heat, cool cycles you minimize the over bending and stress relieve each time. And yes, I will have to do what Flight Design says. But, if they say that it can't be straightened and re-used, they would be going against established practices in aerospace. Quote Link to comment Share on other sites More sharing options...
sandpiper Posted January 26, 2020 Report Share Posted January 26, 2020 I agree with Tom. But, if you do this it should be entered in your logbook. And, since there is nothing in the airframe maintenance manual outlining this repair, that means FDUSA approval most likely with an MRA. For the same reason, your IA friend cannot make or supervise/sign off this repair. Quote Link to comment Share on other sites More sharing options...
johnnyjr Posted January 26, 2020 Report Share Posted January 26, 2020 Keep in mind this may fall out of FDUS’s ability to approve and they will want to send it to Germany for review, a cost of $1200. I just went through this for a fuel tank repair. Ended up not needOmg to take the route that needed the review in Germany, but I did learn this bit of info. Quote Link to comment Share on other sites More sharing options...
ibjet Posted January 26, 2020 Author Report Share Posted January 26, 2020 Thanks for the input gentlemen. I will keep y'all posted. Quote Link to comment Share on other sites More sharing options...
dabaero Posted January 27, 2020 Report Share Posted January 27, 2020 It is very impressive all of the work you have completed on your engine mount! I think the engine mount is made from ST37 which is the same as SAE1013. ST37 is a low carbon steel which is not heat treatable... looking forward to your updates. Quote Link to comment Share on other sites More sharing options...
ibjet Posted February 1, 2020 Author Report Share Posted February 1, 2020 Arian at Flight Design USA sent me the Engine Mount Installation drawing and after studying that, checking out my Engine Mount, I realized that the problem was 95% with the lower left engine mount tube. It was fabricated mis-located about 1/4 inch! Arian said that there were no approved repairs for the Engine Mount and that they wouldn't be able to do any. He said that he and Tom had discussed it at length and they recommended that I use it "as is"! I told him that it must not meet the weldment Drawing and I requested that they submit the problem to someone with Design Cognizance. Also requested they get me a copy of the weldment drawing. This evening I sent him an illustration showing my idea of a weld repair and asked him to negotiate an MRA with Flight Design. He had earlier told me that they have some Engine Mounts on order, they are about $3200! He also recommended that I might talk to AirTime in Tulsa about a possible used engine mount. I think they will feel compelled to help me. I have a discrepant part that Flight Design installed/signed off on! Quote Link to comment Share on other sites More sharing options...
ibjet Posted February 9, 2020 Author Report Share Posted February 9, 2020 I sent a 7 page MRA to Flight Design in Europe, with a copy to Arian. Thought I would see if I could share it here (.pdf). I bought a mini surface plate and I'm making a 24" height gauge (from a 24" digital read out) so that I can know more accurately what the dimensions are. MRA - Engine Mount all pages.pdf Quote Link to comment Share on other sites More sharing options...
ibjet Posted February 12, 2020 Author Report Share Posted February 12, 2020 Surprisingly, I heard back from Flight Design Europe already, "Natalia" answered me, ha ha. She said they could not approve my request because I was altering the configuration of the part (meaning that the strength evaluations would not be valid). I replied, and asked if they could give me some help on the price of a new Engine Mount (since it they built it with a 1/4" error in the one engine mount tube). Then this evening I realized I could fix the part (actually more simply) and not alter the configuration. I sent this photo edit to her . . . Quote Link to comment Share on other sites More sharing options...
AGLyme Posted February 12, 2020 Report Share Posted February 12, 2020 As a former aerospace parts maker, I don't blame FD... no aerospace company can/will take the risk of a part alteration in the field. If I were in your shoes, I would bite the bullet, buy the new part and trust that you will get some value out of the purchase when you sell the plane. Versus having to explain the log entry to an appraiser on behalf of a new buyer that you altered the part. Quote Link to comment Share on other sites More sharing options...
FlyingMonkey Posted February 12, 2020 Report Share Posted February 12, 2020 If the strength of the part is not currently compromised (and it doesn't sound like it is), I'd follow Arian's advice and use the part as is. Even if the geometry is slightly off, it's unlikely to cause any problems, and can probably be shimmed back into acceptable specs. Sometimes building a better mousetrap leads to getting your fingers caught. That frame does a lot of things (locates the engine and sets down angles, sets the geometry for the nose gear, and attaches the BRS bridles, to name a few). It's hard to predict how altering it will affect all of these functions simultaneously. I have to ask: Is there an actual observed fault with the airplane you are trying to correct, or are you just "fiddling" ? If the latter, I'd say follow the factory advice and leave well enough alone, use the part as it exists, and when installing it get it as close to factory specs as possible. You already have factory guidance that it's safe to do so. I'm guessing a new part is $3k-5k or more, and there's no guarantee the new part geometry will be any better than the current one. My airplane sits 1.5" lower on the right side than on the left. This causes occasional headaches and I have to be care parking on inclines with full fuel to avoid vent overflow, but the airplane lands and taxis just fine. I have carefully inspected the gear legs and mount and can find no cracks, bends, or other defects, so it's possible that something was misaligned at the factory, or slightly tweaked by the previous owner in a hard landing. I just live with it. It's not a safety issue, and I have about 1200 landings on the airframe with the gear in that configuration. Sometimes you just have to accept that these airplanes are hand-built and not going to be perfect, and move on. Trying to make them perfect will drive you crazy and can create more trouble than it solves. Just my opinion, it's worth what you paid for it... Quote Link to comment Share on other sites More sharing options...
ibjet Posted February 12, 2020 Author Report Share Posted February 12, 2020 AGLyme: General Aviation airplanes get modified in the field all the time. My M20C Mooney had a huge stiffener plate added to the left and right wing spars to repair corrosion that was caused by sealant stripper. There was a design submitted to the FAA done by a mechanical engineer who was FAA Certified. You just have to go thru the correct procedure. Andy: A conference between Arian and Tom at FD USA does not constitute Factory Advise. See my update below, apparently "The Factory" is concerned enough to offer me a healthy discount on a new Engine Mount! But, regarding the mis-located engine mount tube: Look at my MRA, Sheet 5. How much torque do you think it would take to align that lower left engine mount tube with the hole in the Engine Frame? I'm guessing about 100 ft/lbs (oh, you also have to pull it sideways too). Now, once you achieve that and you have your engine assembled, see what happens after a couple of years of flying (see MRA, sheet 4). You have metal to metal contact within the lower left engine mount tube. Engines are rubber mounted to isolate out vibration. So, is 3 out of 4 close enough? Come to think of it, my level of engine noise in the cabin is very high (I don't have any other CT's around to compare it to). I bet it will be much quieter once I get it back together with new rubber. But, the vibration has many undesirable affects. I assume my airplane has been like this from day 1. Does that mean I should re-assemble it like that, HELL NO! In aviation, when you see a significant issue you get it evaluated by experts and then you do "the right thing". I do have 2 updates: 1). Tom Peghiny called me a while ago and said they are offering me a new Engine Mount for $2000 plus shipping (about $1200 off list). 2). Natalia says engineering wants stiffeners and a load test afterwards! I plan to add stiffeners to my photo edit and show Natalia my straightening fixture, which I can use to proof load one leg of the mount at a time. I have a 440 lb. digital scale but I'll probably have to get a 1 ton digital scale or load cell. Pretty sure I'll go with the new Engine Mount, but I'll first go to UPS and give them the estimated weight and box size and ask how much shipping would be. Appreciate the input Gentlemen! ET Quote Link to comment Share on other sites More sharing options...
FlyingMonkey Posted February 12, 2020 Report Share Posted February 12, 2020 Well for two grand it's probably worth it to just replace it. As far as "factory advice"...FD-USA is the factory representation in North America, Arian is the technical support rep and Tom runs the company. If they say "fly it that way" then that IS factory guidance, from a legal perspective. Of course I don't know all the circumstances or context, and if you are not comfortable with that and they offered you a lower cost replacement option, then there's your answer! BTW, be prepared that you might have to do a lot of trial-and-error fitting and shimming to get the new mount to fit well with proper down angle and offset, especially if your original mount was bent when the airplane was assembled. I'm sure it will all work out in the end. Quote Link to comment Share on other sites More sharing options...
AGLyme Posted February 12, 2020 Report Share Posted February 12, 2020 Right. Perhaps you mentioned this in previous posts... I’m on my cell and have to run to a meeting...do you have a certified engineer who will sign off @ FD specs to clear you for the work you propose a la your Mooney fix ? The engineer in essence takes the risk of a repair or engineer change. And the engineer charges you $ for the risk he/she takes. Andy’s advice is best I think. Reinstall the existing mount and call it a day. The tweaking involved in acceptance of the new rig may pave the way for several other headache tweaks. It doesn’t sound like this mount was damaged during landing. Quote Link to comment Share on other sites More sharing options...
Tip Posted February 12, 2020 Report Share Posted February 12, 2020 The shimming at the firewall affects the rudder linkage. Quote Link to comment Share on other sites More sharing options...
FlyingMonkey Posted February 13, 2020 Report Share Posted February 13, 2020 15 hours ago, Tip said: The shimming at the firewall effects the rudder linkage. It shouldn't cause a problem. If the rod ends are adjusted properly the nosewheel will track straight and the rudder linkage will be neutral. The only way I could see shimming throwing anything out would be if a rod end ran out of travel do to really big shims on one side. If you meant that the linkage will need to be adjusted with a shim change, that is absolutely true. Quote Link to comment Share on other sites More sharing options...
Tom Baker Posted February 13, 2020 Report Share Posted February 13, 2020 I think the point Tip was trying to make is that any shimming, or simply any dimensional change in the position of the nose gear horn connection points will require adjustment of the rods to set rudder cable tension. It will also require checking and possibly resetting the rudder travel. Also the 6 mounting holes on the new gear might not line up with the existing hole in the airframe. In this case you would need to get instructions from Flight Design on filling the holes and relocating them. Quote Link to comment Share on other sites More sharing options...
Tom Baker Posted February 13, 2020 Report Share Posted February 13, 2020 20 hours ago, ibjet said: AGLyme: General Aviation airplanes get modified in the field all the time. My M20C Mooney had a huge stiffener plate added to the left and right wing spars to repair corrosion that was caused by sealant stripper. There was a design submitted to the FAA done by a mechanical engineer who was FAA Certified. You just have to go thru the correct procedure. You are correct, except it is some General Aviation planes get modified. You explained the process nicely, but it doesn't apply to all GA aircraft. For a SLSA the process of repairs lies with the manufacture, and you can't make a repair without their approval. When a manufacture goes out of business and there is no longer any support for the airplane they force you to switch to ELSA, and repair isn't an issue. So as long as the manufacturer of a SLSA aircraft is still in business you are required to follow their procedures for any repairs, regardless of how things are done with other GA aircraft. Quote Link to comment Share on other sites More sharing options...
FlyingMonkey Posted February 13, 2020 Report Share Posted February 13, 2020 That is the "weirdness" of SLSA...repair and alteration procedures are not standardized per the FAA, they rest solely with the manufacturer. It leads to wildly varying standards and procedures between LSA makes/models. It's a two edged sword. On the one hand, we get relaxed but safe standards per the ASTM guidelines, on the other hand, we're pretty much at the mercy of the manufacturer (ask the SportCruiser guys...do they even have an approved ADS-B solution yet??). IMO the best of all worlds is to take an airplane ELSA, and follow manufacturer recommendations as much as possible and as much as they are reasonable. Quote Link to comment Share on other sites More sharing options...
Warmi Posted February 13, 2020 Report Share Posted February 13, 2020 1 hour ago, FlyingMonkey said: ..... IMO the best of all worlds is to take an airplane ELSA, and follow manufacturer recommendations as much as possible and as much as they are reasonable. Which is what pretty much happens in the automotive industry - you are pretty much free to mess with your car ( either yourself or via proxy - ie mechanic ) to a large extend ( your car still have to pass certain tests like the emission test etc ) but just about everyone follows manufacturer recommendations anyway. Quote Link to comment Share on other sites More sharing options...
ibjet Posted February 14, 2020 Author Report Share Posted February 14, 2020 It's official, FD Europe is offering me a new Engine Mount for $2,000 + shipping. AirTime Aviation has one in stock and they are offering it to me $10 cheaper than the price FD USA quoted me, ha ha. I asked them (Nataliya!) if I could purchase from AirTime and get a rebate from FD Europe to get me down to $2,000. But, I submitted another iteration in my proposed repair work (they said that lateral welds would not be advisable and I remembered they are right). So, I edited a picture again and showed longitudinal welds and stiffeners added to all 4 sides of the rectangular tubing. But, the shocker was that they said load testing would be required! I don't seem to have anyone here interested in my repair (which is actually my plan B now) but I will show my 2 latest edited photo's that I submitted to FD Europe: BTW: If FD Europe offered me a $1,200 discount, I think they are not too proud of my existing Engine Mount. I thought they would make me prove the dimensional error, which I intend to measure more accurately. I have requested a digital copy of the Engine Mount Dwg several times and they have ignored my request. But, yes, I have to get approval from them to do any significant repair. Not sure if I could use an FAA Certified Engineer to approve a repair (via submittal to the FAA), but that would be bucking the system. Quote Link to comment Share on other sites More sharing options...
Mike Koerner Posted February 15, 2020 Report Share Posted February 15, 2020 Jet, WIth respect to your last sentence... I think you need to re-read what Tom said 4 posts earlier. It has nothing to do with the FAA. They can't approve a mod to a SLSA aircraft. Mike Koerner Quote Link to comment Share on other sites More sharing options...
AGLyme Posted February 16, 2020 Report Share Posted February 16, 2020 News to me too re FAA approval vs LSA rules. That’s my takeaway in this post. Thanks Tom. jet, I forgot, was performance using the original mount “bad”? Meaning, what operating benefits will you achieve with a new/repaired mount ? admire your pluck. Quote Link to comment Share on other sites More sharing options...
Tom Baker Posted February 16, 2020 Report Share Posted February 16, 2020 On 2/13/2020 at 9:04 AM, FlyingMonkey said: That is the "weirdness" of SLSA...repair and alteration procedures are not standardized per the FAA, they rest solely with the manufacturer. It leads to wildly varying standards and procedures between LSA makes/models. No widely varying standards. What ever the manufacture they have to figure out the repair, and the engineers need to determine that the repaired aircraft still meets ASTM standards. Quote Link to comment Share on other sites More sharing options...
ibjet Posted February 16, 2020 Author Report Share Posted February 16, 2020 AGLyme: My engine was sagging making my spinner come too close to the lower engine cowling. I decided I did not want to try to force it back together with my new engine mount rubber. Pre-loading a structure in aviation is a big no-no. The pictures in my MRA posted above (Feb 9) tell the story pictorially (sheet 3, 4, 5). FD USA said I should "use as is" based on "well, it worked before". I requested someone with design cognizance (FD Europe, Engineering Dept) review and advise. I don't think FD USA forwarded my request, but I did my MRA, submitted to FD Europe, and CC'd FD USA. I'm up to my 3rd iteration of configurations that I have offered to repair my Engine Mount. They have not said "use as is", they have offered me $1,200 discount on a new Engine Mount, and they have had issues with all my repair configurations (but I have not heard back on my last submittal). Tom Baker: I do not like to delve into "legal" procedures. I genuinely did not know if I could use some procedure to authorize a repair thru the steps that would be used for general aviation. The FAA created the LSA class and the rules and they modify them at will thru there existing process, as they are doing currently. I am well aware that the procedure requires me to request approval thru the Mfr. for any repair not in there existing manuals or blanket MRA's, that's what I'm doing. I do believe I would have the legal right to ask for financial compensation for this effort because they sold an airplane with an Engine Mount that did not meet their drawing. But, I figured I would just negotiate my best way out of this and go for it. Thanks again for your input gentlemen! ET Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.