Notification 17-05-19 Soft Engine Isolators
 

This one is pretty new, and I couldn't find any posts about it. Apparently there were some soft engine isolators that shipped with some of the firewall forward kits. The order ship dates for these soft isolators was from August 5, 2009, to June 30, 2016. Wow! That's wide range. Anyway, according to the notification you need to look for raised text somewhere around the exposed perimeter of the isolator. Since it was oil change time, and I had the cowl off, it was a perfect time to do the inspection. Sadly, all four of my isolators are missing the raised text. So, I followed the instructions which was to contact Van's. They are sending out the correct isolators. According to the notification, it is a 6 hr job to replace them, and you are to use section 46 of the builders manual as a guide. I'm not sure what needs to come off to do this, but it looks pretty intimidating to me, almost like a complete engine R & R. There is no specific outline for changing them, other than the builders manual, but I am hopeful that I will find some shot cuts as I go through the process. Anyone else hit with this one? The good part is that Van's folks watches out for us, and are prompt to notify us and make it right.

Oh, snap. I'd seen the earlier notice but not this one. The earlier one was a much narrower range of dates. I need to check mine tonight... the good news is, I'm doing the annual so at least the cowl is already off.

I wasn't included in the original date range but was included in this latest one. Thankfully, mine have the raised lettering so I'm OK. I don't think I could replace them in 6 hrs :(

I saw that notice just recently and suspect that mine are also the soft type. As it's a notification and not a service bulletin, I'm wondering what issues the softer isolators may cause. Cowl rubbing? Engine problems? Maybe Scott could explain.

I had to change the mounts on my plane not too long ago, I had the ones with the purple dot.
Was not looking forward to it since they looked good and the plane has not been in the air yet. I checked with Vans, they said the should be replaced but gave no explanation why.
So I replaced them.Its not as bad as it sounds.
I used an engine hoist at the engine and you need a support for the tail.
As I remember I only had to remove a fuel line at the gascolator and a clamp for the Wireing bundle to get some slack.
Loosen up all nuts on the engine mount bolts all the way, lower engine slightly and replace upper mounts. Leaving upper mountings loose all the way rise engine to get enough clearance to replace lower mounts.
With the new engine mounts the gap between the upper cowl and the spinner is about 1/16" less.

That's reassuring at least. Thanks for the description.

Thanks...you make sound much less of a hassle than I was trying to picture! And I thought I had finished my annual.....if these "service" change-outs keep coming I'll be lucky to get in the air this Summer!

Oh boy, this is not good news! I did not recieve a "notification". Was it emailed? At least I'm in the midst of my annual so its the right timing, if I have to do it.

I don't think that any notifications were sent out, at least I didn't receive one either. I just happened to take a look at the list on Van's support site, saw the notice, and decided that I needed to comply. My thoughts are that with the soft rubber, when you torque to specs, you may wind up with no rubber dampening at all, due to the sleeve bottoming out on the washers and mount, effectiviely leaving you with a solid mount. I appreciate the write up from Ueli. His experience makes me think that it won't be a terrible task after all. By the way, I have no purple dot, no white dot, and no raised text, for what it's worth. I may see some evidence of them when I get the old ones out, but I carefully worked my way around all four front and back rubber mounts using a mirror and found no markings at all.

E-mails are only sent out for Service Bulletins

A Notification is only issued for things that are not safety of flight concerns.

The soft isolators can not be over compressed because there is still a spacer that the bolt torques up on.

Scott, can you elaborate on what lead to this notification?

Today I did the same and saw no raised letters. Then my grandson took a look with his younger eyes and claims to see what might possibly be the very edge of some letters peeking out from under the metal part of the mount. I am going to have to dissassemble at least one of them to see for sure if there is lettering buried in there. Tomorrow......

BTW, if one of the four mounts is found to be of the "good" type, does that mean that one can assume that all four are good? Or could they be from two batches in the same kit?

John, the bulletin states that if raised text are found on one half of an isolator, that isolator is considered good, but not all of them. So, basically you need to find raised text on at least one half of each isolator, At least that is the way that I read the notification document.

Good morning. Hopefully Scott will weigh in on this question. I dont want to have to take them ALL apart just to see.

Hey Ueli!

Do you remember how much room you needed to get the old isolators out, and the new ones in? Would it be more or less than an inch? I'm trying to figure out how much slack I will need in wiring, hoses, etc. It would probably be best to create sufficient slack first, rather than deal with a tight wire or hose later.
Thanks..............Tom

Thanks for the tips on changing these out. Always nice to hear from someone who has been there, and done that.

Actually, with a small mirror and a light I was able to see all the way around most of the isolators.

Tom

It was discovered that at some point the supplier had mixed in an alternate part with at least one shipment of parts to Van's.
At the time of discovery, there was info that indicated that delivery of the incorrect part was isolated to a specific time frame, but additional information obtained later indicated that it was wider than that time frame.

If I remember correctly the parts are individually packaged (not in a boxed set of four) so the recommendation is that all four on an RV-12 should be checked.

Thanks Scott. With more careful examination using a small mirror and strong light I was able to positively identify one mount, and see partial raised lettters and/or white dots on the other three, enough evidence to satisfy me. I think I am good.

Since my new isolators arrived from Van's yesterday, I changed mine out today. Not a bad job at all. I took the battery out, the air filters off, and needed to move the engine mounted adell clamp that holds the cabin heat cable in place. And of course, you have to open up the front of the tunnel to gain access to the bottom bolts. The only help that I had was when I called my daughter out to hold the bottom bolts from turning that are inside the tunnel, and to swap out the sandwiched isolator pucks while I jiggled the engine around. All the rest was a one man job. Yes, it took me less than 6 hrs start to finish. I was pleasantly surprised with how well the project went. Don't be shy guys. Oh, I do have a small engine hoist, which in my opinion is a must, and don't forget to support the tail before cutting the engine loose. Hope this helps...........Tom

Where can I find a copy of this notification?

I looked and didn't see it in the RV-3 section, the -4, -7 or -10 sections.

Thanks,
Dave
RV-3B now skinning the fuselage

June 9, 2017 Applies to RV-12 Soft Engine Isolators
Notification

Should have picked up on that, sorry.

Dave

Woo-hoo!! Checked all four today and found raised lettering on all four. Just barely peeking out of the engine mount, but it's there. What a relief.

Yup, checked my uppers (which were both okay); back to the hangar tomorrow with my computer bore scope camera/light to check lowers. Just as soon not remove lower cowl.....but Woo-Hoo for at least the uppers!

Yes, very hard to see, only the edges of the lettering show. I was able to see all four with inspection mirror, strong light, and a lot of muttering!

The A/C part Gods favored me!
 

Whoo-Hoo, both upper and lowers are the correct ones. Now, finally finished with annual.

Onto fun stuff to get ready for Oshkosh!

A few questions
 

I have a few questions after trying to check my engine:

- The picture on the notification shows two isolators, one good and one bad. These isolators are actually made of two parts, one male and one female. What is shown here on the picture? Is the part that has the raised letters, male or female? Whatever the answer, the mating part does not show any marking, is it so or is the marking not visible because it is on the other side?

- On the good isolators, is the raised text always following the white dot?

- On the bad isolators are always the marking positioned as on the picture, i.e, in the middle of the isolator rather than closer to the bottom as in the good ones. If they are on the middle they are likely invisible when the isolator is under pressure.

- On the good isolators that are squeezed under pressure is the raised text visible from the bolt head side or from the mount side?

I feel that having answers to these questions would make the inspection more reliable.

My isolators had no markings; no white or purple dot, and no raised text anywhere. This was verified after replacement. The new isolators only had the white dot and raised text on the larger male end. The female had no markings. After installation, only a small portion of the white dot and text were visible. I positioned the white dots so that they could be easily identified with just a casual look. Hope that helps..............Tom

Definitely answers most of my questions, Tom, thanks.
I have a growing feeling that, based on the fact that probably a large number of these soft isolators have been flying with no adverse effect over 8 years. From what I have been able to inspect so far, I suspect my isolators are in the soft category. I have now more than 200 hours of very smooth running of my Rotax 912. I will need to see some hard evidence of damage to disturb the nice operation of this engine through an intervention that could disrupt a nicely balanced FFW setup.

I haven't checked mine yet. I'm waiting for the Arizona outside air temp to drop somewhere in the indicating range! I think Jean-Pierre has a good question: it would be useful to know how this was discovered and what, if any, dangerous condition resulted. Right now it is not clear if someone at the factory just noted they didn't meet specs or if one failed in service.

http://www.vansairforce.com/communit...8&postcount=10

http://www.vansairforce.com/communit...1&postcount=18

From the first link: "The soft isolators can not be over compressed because there is still a spacer that the bolt torques up on."
Could you elaborate on this, I do not understand.

I checked my isolators and can't find any markings on them so I suspect they fall into this notification. On the other hand, I have very little clearance between engine valve covers and cooling plenum on the left side and don't see any evidence of motor movement causing a problem. Airplane has 250TT.

Take a look at the drawing in the manual. The bolt goes through a spacer, so the bolt torque doesn't depend upon the rubber isolator. The fuselage attachment point (WD-1221), bolt, washers, spacer and nut form a solid assembly. When you torque the nuts down there will be some compression of the rubber parts, but the washers bottom out on the spacer and that's what you're tightening the nut and washer against, not the rubber parts.

The first time I checked I was pretty sure I saw no markings. On closer inspection, I could just see the very tops of the numbers along the very edge of the metal "cup". No paint dots are visible anywhere.

Is it possible to install the isolators backwards from what's shown in the drawing - in other words, male half on the aft side of the engine mount, female half forward? And if so, would it make a difference?

Now I get it, thanks Dale. Of course an alternative would be to make the spacer shorter for the soft isolators to allow for more compression but if possible it would be even more work than swapping the isolators!
I still am not convinced that a well balanced engine is at risk with the soft isolators... If something bad happens to the engine that creates lots of vibration, may be? But eh! it's a Rotax 912 not a Continental or Lycoming!:D

Thanks for drawing my attention to those posts, Scott. Sounds like this is precautionary as opposed to a failure having occurred. I feel better about waiting until next oil change in cooler weather to check mine.

Rich

This has nothing to do with whether your engine will run smoothly or not.

As is usually the case with design details, there is usually a lot more to it than people consider.


Here is just one.....

When an airplane experiences a G's exceleration, all components feel it the same way you do.
The engine is connected to the airframe with flexible rubber isolators (the subject of this discussion).
If the correct parts are installed, the engine on an RV-12 will sag more than 1/2" at the spinner during +4 G's.
How much will it sag if isolators that are softer than specified are used? I don't know. Tests were never done to see what happens if wrong parts are used, but I will guess that it be an inch or more.

I have ignored this Notification with plan to address at my annual. On my last long cross country I had strange resonance noises start (around 180 hours on isolators). Grabbing the prop hub I appeared to have excessive engine movement and feared a loose bolt to engine. Removed cowling with no evidence of rubbing or anything wrong. Could find no numbers on my isolators. Reassembled and flew 6.5 hours home with no noise or problems. Called Vans and they shipped the new parts to me for FREE. Great Service!

I'm assuming vibration was being transferred directly to the mounts by the bolt/spacer.

Update: turns out I had numbers on my isolators after all but they we not visible being compressed againt the large white washers. I replaced them with new and do note somewhat less movement. Job took about 4 hours perfomed as indicated in prior posts using an engine lift. The noise appears to have been caused by the right carb throttle lever vibrating against the side frame portion of the carb tray when at nearly full throttle. Obviously with the headwind going I was at higher throttle settings than with a tail wind upon return. Quick work with a file gave more clearance.

"Called Vans and they shipped the new parts to me for FREE. Great Service!"

That's a pretty good deal. They charged me $40 to fix their mistake.

This was tough to do without loosening the mounting bolts, but with an endoscope I was able to see the top little bit of the markings.