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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: 33
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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Grand Junction, CO
RV-8A N751MB -1700 hours, sold
RV-14A N465MM - 280 hours and climbing
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  #42  
Old 07-09-2018, 11:22 AM
azflyer21 azflyer21 is offline
 
Join Date: Nov 2016
Location: Scottsdale AZ
Posts: 69
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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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Bill Marvel
Grand Junction, CO
RV-8A N751MB -1700 hours, sold
RV-14A N465MM - 280 hours and climbing
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