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  #1  
Old 11-17-2010, 07:42 AM
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Geico266 Geico266 is offline
 
Join Date: Feb 2005
Location: Huskerland, USA
Posts: 5,853
Default RV-12: Engine Mounting Cap Screws Inspection

This is a FLIGHT CRITICAL situation that IMHO requires inspection and corrective action before next flight.

Flying RV-12's owners should take immediate action to check the 4 engine ring mount socket head cap screws before next flight. Many bolts have vibrated loose, and several have fallen out!

During a recent inspection I found the two bottom socket head cap screws that hold the engine mount ring to the engine had worked themselves loose. I pulled them out, inspected the threads, added blue loctite, and retorqed to 26 ft pounds, and I didn't think too much about it until Tony T contacted several of us last week with the same issue. Then the flood gates opened. Nearly everyone Marty S & I talked to flying the RV-12 has had the engine mounting cap screws come loose around 100 hours.

The top two engine mount cap screws have also been reported loose also so all 4 need to be checked. The bottom two are easy access. The top right needs to have the carb & carb socket and drip pan removed. The upper left is inaccessible and the cooling shroud will need to be modified. John Bender was able to get at it by modifying the cooling shroud.

The plans do not call out blue loctite on these bolts and IMHO there should be.
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Last edited by Geico266 : 12-02-2010 at 01:23 PM.
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  #2  
Old 11-17-2010, 07:58 AM
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Geico266 Geico266 is offline
 
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Location: Huskerland, USA
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I first noticed by lower two were loose about 3 months ago when I was changing oil.

Yes, they had lock washers on them.
Yes, I torqued them to specs the first time.
I did not use loctite the first time per the plans.

After adding blue loctite, and re-torquing to 26-30 ft pounds I have flow 50 or so hours with no further problems. I check them every oil change or 25 hours, and whenever I have the lower cowl off. Since they were re-installed they have been fine.

I highly suggest adding "witness marks" with a black marker or torque seal so there is a visual reference on the heads of the cap screws.
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RV-10 : In the hangar
RV-12 : Built and sold!
RV-44 : 4 place helicopter on order.

Last edited by Geico266 : 12-02-2010 at 01:30 PM.
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  #3  
Old 11-17-2010, 08:01 AM
JBPILOT JBPILOT is offline
 
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Location: Jesup, Iowa
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Default THANKS LARRY - NEEDED THREAD

I have a lot of hours now ( over 200 ), and likely was one of the first to have this problem. When I first found it, like Larry said, I thought I had made a mistake, and added Loctite 'blue', and did all 4. ALL 4 were loose. I Dremeled out a large enough section of the airduct to give access. I 'glued' the piece back in place and went on. The SECOND mistake I made was to not go back and look at the instructions to see if Loctite was called for. I ASSUMED it was, and I just made a mistake. That mistake was almost worse than the first. After Tony T. sent us a note a few days ago, I realized I made the biggest mistake of all, not telling others of my problem originally. 2 or 3 wrongs does not make a right for sure ! Since I put Loctite on mine ( several months ago ), mine have not moved. I used a marker pen and 'marked' all 4 bolts so I could see if the bolts moved.

We now know at least 7 of us early builders who have had this problem. IT IS A PROBLEM !

THIS COULD BE A MAJOR PROBLEM. Check them and forward the info to Van's.

John Bender
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  #4  
Old 11-17-2010, 09:15 AM
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MartySantic MartySantic is offline
 
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Location: Davenport, IA
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Default

To ensure the engineering folks at Van's receive your report, do the following.

There is a reporting procedure (required by ASTM standards) in the RV-12 Maintenance Manual section 16-1. Safety issues should be reported so there is a record.

E-mail to:

engineering@vansaircraft.com
'Safety Alert' (in subject line)

For this issue include your total time, a qualitative description how loose each engine mounting bolt was, and whether or not you added locktite.

SEVEN of us NOW with 85 to over 200 hours have found LOOSE ENGINE MOUNTING BOLTS.
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  #5  
Old 11-17-2010, 10:26 AM
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Geico266 Geico266 is offline
 
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I have talked to three major Rotax Service Centers and they all say adding violet (strong) or blue (stronger) loctite to the engine mount cap screw certainly will not hurt anything. One even suggested using green (stronger yet) loctite if the bolts continue to move. All of them suggested not to use red (strongest) loctite in this application. Retorquing to a higher level helps for a longer peroid of time, but did not solve the problem of these bolts coming loose. Blue loctite was strongly recommended by experienced Rotax mechanics, and aircraft manufacturers I talked to.
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RV-44 : 4 place helicopter on order.

Last edited by Geico266 : 12-01-2010 at 05:16 PM.
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  #6  
Old 11-17-2010, 02:13 PM
mcems mcems is offline
 
Join Date: Apr 2008
Location: Salem SD
Posts: 146
Default

Add one more.

190 hours

Lower right just about all the way out.
Lower left had to go 1/4 turn to get back to specs.
Upper right OK still at specs
Upper left visual only looks OK. (not able to use wrench)

These all looked OK @ time of annual inspection 140 hours. But annual inpection was only visiual looking at the tourge seal I used at the time of the build. Myself and a 30 year A/P both looked at these at anual time.

This is a serious issue. This all took place in the last 50 hours.


Brad Stiefvater
124bj
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  #7  
Old 11-18-2010, 10:06 AM
kell311496 kell311496 is offline
 
Join Date: Dec 2008
Location: Benton, KY
Posts: 23
Default

Mine also loose - 97 hours. I used a dial-type torque wrench to note the approximate torque before they started turning:

Lower right - 80 in-lbs
Lower left - 120
Upper right - 250
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  #8  
Old 12-02-2010, 05:47 PM
Boomerang Boomerang is offline
 
Join Date: May 2009
Location: Grand Island, Nebraska
Posts: 22
Default Loose bolts on N7185A, SN#120164, with 52 hours

Checked the bottom two bolts right after Larry called me (Thanks Larry) and found the bottom right tight. The bottom left needed about 1/8 turn. Was not able to check the top two bolts at that time because of the inaccesability. The top right looked OK but I really did not look very close at the top left. Just assumed that it was OK. Did a closer visual check today of the top left bolt. The bolt head is just about even with the outside edge of the engine mount. How loose it is (how many turns counter clockwise) I won't know until I can get in there but as a result I am grounded until I can get my 12 to a heated work area. This will take a while. A real bummer.
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  #9  
Old 12-02-2010, 08:33 PM
dick seiders dick seiders is offline
 
Join Date: Jan 2006
Posts: 889
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Heard from Rotax Tech again today. He was not willing to commit on the blue Loctite, but I have read enough to feel firm on the 360 torque setting, blue Loctite, and torque seal with checks at each oil change. Until something better comes along, if it does that's where I am going.
Dick Seiders
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  #10  
Old 12-02-2010, 09:16 PM
Peterk Peterk is offline
 
Join Date: Mar 2008
Location: Texas
Posts: 1,378
Default What is Going On?

Quote:
Originally Posted by dick seiders View Post
Heard from Rotax Tech again today. He was not willing to commit on the blue Loctite, but I have read enough to feel firm on the 360 torque setting, blue Loctite, and torque seal with checks at each oil change. Until something better comes along, if it does that's where I am going.
Dick Seiders
Certainly is curious. Bolts coming out right and left. Van's doesn't care, the Feds don't care (or don't read VAF...yah right). Those that Loctite swear by it, but neither the engine manufacturer nor the aircraft manufacturer...whom both recommend Loctite in much of the remaining assembly will not do so in this instance. What a bizarre situation! Of course no one did anything about the Zenith wings coming off until how many crashed? Am I missing a liablity issue here? Guess we'll find out when the first 12 smokes a hole in the dirt.
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