New Service Bulletin today.

[radfordc]

Can you give us a quick tutorial on what you did?

[vigilant104]

I had no luck finding Loctite Primer at any local stores so I completed this without it; I was told that the only real purpose of the Primer is to accelerate the cure time of the actual sealant. Has anyone heard this? I'm not opposed to performing this job again if the Primer is actually needed, but most feedback thus far says that, as long as you let things cure a full 24 hours, it's not really needed. Regardless, I plan on letting the sealant cure for a few days then check the screws after a few hours of flight time.

Mike,
I've never used the primer before. Here's the manufacturer's page that discusses when the primer should be used: http://www.henkelna.com/industrial/using-a-loctite-threadlocker-14064.htm It looks like the primer does speed up the cure, but they also say:

For Inactive Metal Assemblies
When assembling metal parts with inactive surfaces, Loctite® primers are recommended to ensure proper performance of Loctite threadlockers.

Among the "inactive metals" they list anodized aluminum, pure aluminum, stainless steel, and cadmium. They don't say whether the primer is needed if one side of the "joint" is "active" and the other is "inactive", or if the primer is only needed if both sides are "inactive". Obviously, the Sb says to use it, so that is the best course of action.

I'll try to find the primer while I wait for the parts to arrive. It looks like there are two primers Loctite makes for their anaerobic thread lock products: Product 7088 is a semisolid stick and Product 7471 is a liquid. Both are pricier and harder to find than the threadlock product itself.

[MichaelFarley56]

Can you give us a quick tutorial on what you did?

Charlie, if you're talking about how I performed the SB, this was the basic procedure:

1. Remove cowling and disconnect battery.
2. Unhook and remove starter from the red X casing.
3. Remove the alternator stator cover plate (stupid powerful magnets!)
4. You now have access to the 4 screws that get replaced. Remove them (I did all at once), and install the new longer screws, tightening using the provided instructions on the engine build manual sheet.
5. Reinstall alternator stator cover plate, starter, and reconntect battery. I turned the prop over by hand to make sure the secondary ignition trigger was still centered between the triggers.
6. Install cowling. Done deal!

Mark, yeah I was wondering about that. I found it interesting that the engine build manual makes no mention of using a primer on these bolts when you build the engine initially (it says to use Loctite #242 only), yet the SB indicates you should use a primer. The screws are zinc plated steel so perhaps it's a good idea to find said primer and use it! I have an email in to the factory to see how important the primer is, and if it's necessary, what kind to get. I'll let you know!

[SonexN76ET]

Mike,

The Aerovee manual that came with my engine designated using the loctite primer. I did not think it was necessary and asked Kerry about it. He said it is necessary to prevent the screws from backing out. I was able to order some from Amazon.com. The loctite primer really helps to form a strong, weld like bond. Thecurrent Aerovee manual found online at Aero conversions.com designates the correct primer. It is a stick, like an Elmer's glue stick. It was about $12.

[corton]

Charlie,
Thanks for posting this, I've got my order in. For whatever reason, I didn't get the SB email from Sonex-- I'll have to be sure I gave them my current email address.

Mark, I don't believe that Sonex automatically sends out SBs to owners. I received notice only cuz I subscribe to several of their email lists.

Carl

[MichaelFarley56]

Just as an FYI to those who may be looking for a Loctite Primer for this SB: It looks like the AeroVee manual states the use of Loctite 7088 primer which can be a little challenging to find locally, but it does appear that Fastenal retail stores carry it. If you have a Fastenal around, check with them. I just picked up a tube for around $18. Worth a shot!

Thanks for the reply's everyone!

[adroit]

The Loctite Primer #7088 is available from McMaster-Carr at www.mcmaster.com See the following info: Sonex has now committed to a torque value of the trigger shaft screws of 10 to 14 foot pounds with a properly calibrated torque wrench. Check with Kerry Fores for verification and all further questions.

Loctite® Primers, Accelerators, and Cleaners

Prepare your surfaces for bonding with these primers, accelerators, and cleaners.

Primers ensure strong bonds, especially when applying adhesives in low temperatures, or to large gaps or deep threads. Recommended for aluminum, galvanized steel, magnesium, stainless steel, steel, and titanium as well as plated parts and black-oxide coatings.
Loctite
No. Size Color Each
Primers
For Threadlockers

7088 0.59-oz. Stick Amber 66205A27 $14.67

Product Detail
Loctite® Primer for Threadlockers, #7088, 0.59 oz. Stick
Each
In stock

Bill Dodson
Xenox #031

[adroit]

Re. AeroVee Service Bulletin, Reference Number ACV-SB-061714 Date of issue: 06.17.14

The third paragraph in this Service Bulletin states, "All AeroVee Engines sold since late 2012 include the longer (ACV-Z01-81) cap screws". This indicates that Sonex LTD had knowledge of a potential problem with the shorter (ACV-Z01-36) Flat Head Socket Cap Screws that hold the trigger shaft assembly to the flywheel, for at least a year and a half. And during that year and a half interval, I think Sonex would concur that there were several AeroVee owners that had reported extensive damage to their alternator,stator and rotor as well as the triggers and trigger shaft. In May of this year, our AeroVee engine became part of that statistic as we reported to Sonex that there was extensive damage to all components from the flywheel out to and including the triggers. Essentially, we replaced everything, including the voltage regulator, at a cost of about fourteen hundred dollars. With the exception of the voltage regulator, all the damaged parts were sent to Sonex per their instructions. After inspecting the parts, Sonex determined that the failure was due to the four trigger shaft screws coming loose, which they said was our responsibility. There was no mention at that time by Sonex that they had changed the length of the screws to be used a year and a half ago, "To provide added thread engagement to help prevent these screws from potentially backing out".

We were confident that we had followed the AeroVee Builders Manual verbatim, so there was nothing we did to cause the problem. We reminded Sonex that there was no torque value assigned to the trigger shaft screws, so we had no way of knowing how much torque to apply to them, therefore, Sonex should bear some of the responsibility of mitigating the damage that was done. Kerry Fores replied that it was the builder's responsibility to research the correct torque value if there was none listed or ask Sonex for that information. We then relied on Sonex for the torque value for the repair which Kerry Fores said was a minimum of 10 ft. lbs. and a maximum of 14 ft. lbs. (with the caution: These numbers assume a properly calibrated and operated torque wrench.)

In light of the above, we are puzzled about two things:
1. Given the fact that Sonex started putting the longer trigger shaft screws in their engine package the latter part of 2012, why did they wait at least eighteen months before they alerted the Aero Vee community to the potential problem?

2. Since they are now committed to a specific torque value for the trigger shaft screws, which according to them was critical in our case, why did they not also share that information with the AeroVee community by listing the 10 to 14 ft. lbs. torque value in the AeroVee Service Bulletin ACV-SB-061714?

Bill Dodson
Xenos 031

[vigilant104]

Has anyone else had a tough time removing the original cap screws? When I got to them (concur with Mike: darn those crazy-strong magnets!), I ended up twisting my hex wrench permanently without budging the first one. Now, I can get a hex bit socket in there with a breaker bar and I'm sure something will move, but if the "something" is the rounding out of the internal hex socket on the screw caps, then I'll really be in a bad spot. And surely wishing I'd left well enough alone.

It's hard to believe these things will ever back out on their own.

TIps, hints, advice?

[MichaelFarley56]

I'm sorry to hear that Mark. If those were originally installed with high strength Loctite they'll be a pain! Maybe some heat to help? Do you have a good soldering iron to heat up the screws a little so the Loctite will melt?

Of course, if they're that tight and you're okay with it you could consider just leaving them alone and checking them every condition inspection.

Good luck! Let us know how it goes.