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  #41  
Old 07-09-2018, 08:31 AM
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bmarvel bmarvel is offline
 
Join Date: Aug 2005
Location: Grand Junction, CO
Posts: 39
Default Oil canning and skin cracks

FWIW I have no cracks in evidence after 280 hours on our -14A, but....

1. In the 51 years I've been flying light airplanes I have owned several and built three and long ago learned this reality: unanticipated problems always occur and you have to deal with them by first determining your options, evaluating the pros and cons of each and then selecting the best one.

2. In addition to the annual condition inspection I also do 25 and 50 hours inspections of my own design. Each of these includes laying on the creeper and cleaning the belly. But that also gives me the opportunity to inspect all those rivets and stringers too. As I said, so far so good on our airplane but I am confident Van's will come up with a solution to cracking for those who have encountered it. That solution may or may not be applicable to existing airplanes which, like mine, have not had the problem. I encourage builders to await feedback on a Van's solution prior to trying to solve it yourself. As they said, this is not an airworthiness matter.

3. To reduce/eliminate both oil canning and fuselage skin vibration that occurred on our -8A (1700 hours and sold) and -14A, I installed sound and vibration damping panels from Spruce (part number 09-30206). These are effective, light weight and inexpensive. The adhesive backing allows quick and easy installation on the inside of the fuselage in areas with oil canning. They not only stop the noise but also damp skin vibration over a wide area and I'm certain that reduces the likelihood of localized cracking.
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  #42  
Old 07-09-2018, 11:22 AM
azflyer21 azflyer21 is offline
 
Join Date: Nov 2016
Location: Scottsdale AZ
Posts: 93
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Quote:
Originally Posted by bmarvel View Post
FWIW I have no cracks in evidence after 280 hours on our -14A, but....

1. In the 51 years I've been flying light airplanes I have owned several and built three and long ago learned this reality: unanticipated problems always occur and you have to deal with them by first determining your options, evaluating the pros and cons of each and then selecting the best one.

2. In addition to the annual condition inspection I also do 25 and 50 hours inspections of my own design. Each of these includes laying on the creeper and cleaning the belly. But that also gives me the opportunity to inspect all those rivets and stringers too. As I said, so far so good on our airplane but I am confident Van's will come up with a solution to cracking for those who have encountered it. That solution may or may not be applicable to existing airplanes which, like mine, have not had the problem. I encourage builders to await feedback on a Van's solution prior to trying to solve it yourself. As they said, this is not an airworthiness matter.

3. To reduce/eliminate both oil canning and fuselage skin vibration that occurred on our -8A (1700 hours and sold) and -14A, I installed sound and vibration damping panels from Spruce (part number 09-30206). These are effective, light weight and inexpensive. The adhesive backing allows quick and easy installation on the inside of the fuselage in areas with oil canning. They not only stop the noise but also damp skin vibration over a wide area and I'm certain that reduces the likelihood of localized cracking.
Bill, would you happen to have any pictures of the -14A with the damping panels installed?
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  #43  
Old 07-09-2018, 03:09 PM
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bmarvel bmarvel is offline
 
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Sorry, but I don't. However, it isn't very complicated.

On the ground I determined the center of oil canning by just pressing in on sections of the fuselage aft of the baggage bulkhead. Problem areas were not hard to find. I believe I installed 4 panels, two on each side. These were the six inch wide panels from Spruce but you could certainly use wider ones if you wished.

I did not fill an entire rectangular section between bulkheads and stringers but just placed the strips on what appeared to be the center of oil canning. But I cut the strips long enough to run from bulkhead to bulkhead in the fore and aft direction.

The major reason I did not fill the entire area was that this is a flying airplane. Getting back there with the pitch servo, ADS-B box and elevator pushrods installed while supporting your body weight with one hand and then trying to carefully fit in multiple pieces with the other was more than I felt necessary.

One incentive was that often after landing and near shutdown I'd hear a definite bang from the back of the plane as the cooled fuselage heated in sunlight. This didn't sound appealing (!) and was disconcerting to pax who did not know what was happening. The sound deadening material solved that.

Bill
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  #44  
Old 08-04-2018, 06:15 AM
MED MED is offline
 
Join Date: Jul 2015
Location: Aiken, SC
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Any update on a modification/repair to prevent lower fuselage cracking? I would like to install before first flight, if possible.
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  #45  
Old 08-04-2018, 07:26 AM
SabreFlyr SabreFlyr is offline
 
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Location: Marion, IN
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I spoke with one of the engineering types at Oshkosh (sorry, I donít remember his name). As I understood him, the fix is finalized and the next step is getting the drawings done. Iím sure theyíll then need to be reviewed and a quantity of the parts produced before the kit is released. As he explained it to me, it will be a clip that bridges the bulkhead and ties it to the J-channel. In a number of locations, Iím sure.
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  #46  
Old 08-04-2018, 07:58 AM
larrys larrys is offline
 
Join Date: May 2017
Location: Colorado Springs
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Default Thanks for the update from Oshkosh

I also asked at Oshkosh and Sterling said I was the second person asking but he had no clue there was an issue. Really glad to hear it is being addressed.
Thanks again, Larry
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  #47  
Old 09-26-2018, 01:25 PM
Steve E Steve E is offline
 
Join Date: May 2016
Location: Chandler
Posts: 4
Default Still nothing from Vans regarding a repair for cracks in metal

I checked today and still no service bulletin has been issued for a repair of the cracks or for a fix to prevent them for new builders. Has anyone heard anything from Vans? Allegedly they had their engineers working on it...
Problem is that they were informed of this as early as December 2017.
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  #48  
Old 09-26-2018, 04:13 PM
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Tilford Tilford is offline
 
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Location: KY
Posts: 91
Default J Channel Stiffener clips

It looks like an update to chapter 10 was posted today that shows stiffener clips that attach the j-channels to the bulkhead.
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  #49  
Old 09-26-2018, 04:39 PM
MED MED is offline
 
Join Date: Jul 2015
Location: Aiken, SC
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I spoke with Sterling today, and he checked with someone else, and told me Van's would have word out "in about three weeks." I will look at the chapter 10 update to see if that is the fix. Mitch told me a month or so ago that all affected 14 builders would get an e-mail and that they would also post on the Van's website and here on the forum. It should be obvious when the solution becomes available.
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  #50  
Old 09-26-2018, 04:56 PM
mturnerb mturnerb is offline
 
Join Date: Apr 2015
Location: Ponte Vedra, FL
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I took a look at the new section 10: looks like two simple clips that will rivet to the aft bulkhead (the one with rudder cable crossover) and the two outboard j-channels. Pretty simple except for access - will require crawling back or having amazingly agile arms reaching through from the aft deck area. Two rivets on each J-channel would have to be drilled out, and I'm assuming match-drilling the clip to the bulkhead.
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