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Was Chard-6 (S/N AC-3) the prototype RV-6?

Ron Lee

Ron Lee

Well Known Member
From public sources we can use the FAA registry database to find that one S/N AC-3 aircraft is N424D.

The FAA registry listed owner is the same as news reports as one of the two killed in the crash. One such news report is here:

http://tinyurl.com/cjafonm

In that same report, a NTSB member called the plane an “RV6” yet the FAA registry has the model listed as “RV-6-CH.” These are not identical so at this point there is no obvious tie to the Vans RV6...prototype or otherwise.

In the N424D registration paperwork, in a letter dated January 8, 1996, the requester uses this nomenclature:

Make: RV-6
Type: Airplane
Model: Chard-6
Serial Number: AC-3

And it is stated: “This aircraft has not been previously registered anywhere.”

According to the Vans info on the RV6 series aircraft, that model was introduced in 1986:

http://www.vansaircraft.com/public/rv6.htm

I am not an aircraft designer so many things are beyond my grasp, but it appears patently impossible for an aircraft (N424D, AC-3) which was registered for the first time in 1996, to be the prototype for a model that was introduced about a decade earlier.

So where does the Chard-6 and RV-6-CH info originate. The first apparent use of “Chard-6” is the registration letter of January 8, 1996.

On a Form AC 8050-1, dated 30 Jan 96, in the “Aircraft Manufacturer and Model” block is listed two people’s names along with “RV-6 Chard-6”

That is not the same as the current FAA registry “RV-6-CH”

In the Affadavit of Ownership for Amateur-Built Aircraft, dated 31 January 1996, the Make/Model is listed as RV-6/Chard-6. So the model is a Chard-6, not an RV6.

When you look at the Airworthiness files, there is a letter dated April 2, 1996 where the make/model was noted to be incorrect and was changed from RV-6/Chard-6 to McDaniel/RV-6-CH.

So whether it is a Chard-6 or a RV-6-CH, it is in my opinion not a Vans RV-6 and not a prototype for the plan that I fly now.

This eliminates any concern that I have....as a RV-6A owner...that the crash earlier this week has any relevance to the structural integrity of my aircraft.
 
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Thanks Steve. Very encouraging comments in that article. Based upon info there, it appears that we should get a complete report on the failure. This may be a heads up to people to fully know the pedigree of the aircraft they buy from another owner.
 
My recollections are often faulty but here they are.

My Van's promo tape from around 1995 had a part about the Chard 6. I can't play that now because it is VHS. Van talked about the airplane and showed pictures of it in the context of explaining the evolution of the RV line. Art, a very respected builder, wanted something similar to the RV-4 but side by side and he built the Chard 6. I believe that Van said he flew it and liked it but it was quite a bit slower than the RV-4. Sometime after that the RV-6 was designed and turned out to be not much slower than the RV-4 at all, in fact it turned out to be a great design.

I know little about the Chard 6 except it is certainly not a prototype or the same as an RV-6.
 
n5lp said:
My recollections are often faulty but here they are.

My Van's promo tape from around 1995 had a part about the Chard 6. I can't play that now because it is VHS. Van talked about the airplane and showed pictures of it in the context of explaining the evolution of the RV line. Art, a very respected builder, wanted something similar to the RV-4 but side by side and he built the Chard 6. I believe that Van said he flew it and liked it but it was quite a bit slower than the RV-4. Sometime after that the RV-6 was designed and turned out to be not much slower than the RV-4 at all, in fact it turned out to be a great design.

I know little about the Chard 6 except it is certainly not a prototype or the same as an RV-6.
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Here is the video..... http://www.vansairforce.com/community/showpost.php?p=720792&postcount=13
 
RV6-CH

This link has a discussion of Vans Aircraft that discusses the history of the 6 and the CH origin. It would be a shame to not consider the possibility that N424D might have been a historic aircraft and not a "fraud" posing as a Vans Aircraft. Obviously we know the spar is different, that is not the issue.

http://www.answers.com/topic/van-s-aircraft

I thought the link was hot, but not sure now.

Mike Bauer
RV6 N918MB
 
MontanaMike said:
This link has a discussion of Vans Aircraft that discusses the history of the 6 and the CH origin. It would be a shame to not consider the possibility that N424D might have been a historic aircraft and not a "fraud" posing as a Vans Aircraft. Obviously we know the spar is different, that is not the issue.

http://www.answers.com/topic/van-s-aircraft

I thought the link was hot, but not sure now.

Mike Bauer
RV6 N918MB
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Since another thread has developed on this topic.... just one comment to clear up some possible miss-understandings.
I, and I don't believe anyone anyone else has ever intentionally meant to imply that the chard 6 was a fraud, posing as an RV-6. As has been pointed out, the first one built came well before the Van's Aircraft RV-6 prototype was built.

The only point being emphasized was that regardless of what it was called / named, the airplane involved in this tragic accident was not representative of what a kit RV-6 is, and that RV-6 owners should not panic as a result of this accident.

That statement is also in no way meant to cast blame on the construction of this particular airplane either. Many times, on the surface, accidents initially appear quite different from what they do once all of the information and data is carefully looked at. We need to allow time for that process to take place.
 
This may be repeating info that Gary Sobek already discussed but the other thread was closed. Another apparent Chard aircraft, S/N AC-1 is shown here:

http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=6RV

The Manufacturer Name is Chard and the Model is Van RV-6. I do not recall if it is a two-seater side by side. If it is, then perhaps it was a motivation for the real Van RV-6.

A clue is the Manufacture year of 1977 and airworthiness date of 1980

Given those two dates, calling it a Van RV-6 seems inaccurate.

When I can finally see the video, it may provide more useful info.

Chard S/N AC-2 is also a possible Van RV-6 motivator. As with AC-1, calling it a Van RV-6 when the manufacture year is 1980 seems odd.

Certainly a major point of this thread is that from available data, RV-6(A) owners do not appear to need to worry that whatever caused the wing separation of N424D may apply to their aircraft. At least that is how I view it.

RV-6(A) owners should read the article provided above in Post #2. Ideally, Vans Aircraft will have enough factual info soon that they can officially state that the wing separation event is not a factor.

Post #1 here gives credence that S/N AC-1 is a Chard 6 that may have been the aircraft that helped lead to the RV-6:

http://www.vansairforce.com/community/showthread.php?t=93578
 
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Lest we forget

Ron Lee said:
This eliminates any concern that I have....as a RV-6A owner...that the crash earlier this week has any relevance to the structural integrity of my aircraft.
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Ron,
Structural integrity is based on staying within the limits of a given design criteria. Lest we forget that in 98' the Van's RV8 demonstrator aircraft shed a wing inflight during a demo in AZ killing both occupants.
http://www.ntsb.gov/aviationquery/brief2.aspx?ev_id=20001211X10121&ntsbno=LAX98FA171&akey=1

From the investigation it appears they overstressed the aircraft causing a catastrophic failure of a wing spar. Much discussion ensued on the then internet users group as to the integrity of the single billet spar in the newer "pre-punched" RV's vs the older laminated spars in the 4/6. How the Chard Six center section and spar attach was built is unknown however comma, we can assume that if has flown all these years that some sort of design load challenge was introduced causing inflight breakup.

All we can do is wait for the NTSB report.

V/R
Smokey
Dues gladly paid in Iraq...
Gladly paid to DR anyway...

 
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smokyray said:
Ron,
Structural integrity is based on staying within the limits of a given design criteria. Lest we forget that in 98' the Van's RV8 demonstrator aircraft shed a wing inflight during a demo in AZ killing both occupants.
http://www.ntsb.gov/aviationquery/brief2.aspx?ev_id=20001211X10121&ntsbno=LAX98FA171&akey=1

From the investigation it appears they overstressed the aircraft causing a catastrophic failure of a wing spar. Much discussion ensued on the then internet users group as to the integrity of the single billet spar in the newer "pre-punched" RV's vs the older laminated spars in the 4/6. How the Chard Six center section and spar attach was built is unknown however comma, we can assume that if has flown all these years that some sort of design load challenge was introduced causing inflight breakup.

All we can do is wait for the NTSB report.

V/R
Smokey
Dues gladly paid in Iraq...
Gladly paid to DR anyway...
Click to expand...

Excellent evaluation.

Over time, fatigue can degrade the structural integrity of an airframe. Examples are B737 in Hawaii and SouthWest Airlines that lost part of the fuselage.
 
Smokey, we often hear "Wait for the NTSB report." Yet I saw the report from an accident here last year and it was worthless. My best recollection is that the aircraft was never given the sort of lab analysis that was needed to determine the causal factor.

Another person and I observed an apparent issue with the round tubular spar that could have been an indicator of the problem that caused the crash. Along with unverified rumors, a causal factor may have been determinable.

In the case of N424D, perhaps the two fatalities will place this higher on the NTSB priority list.

The reported involvement of Vans Aircraft personnel is encouraging.

As far as the RV-8 failure, I do not know enough about it to comment. Unless I am mistaken, the wing system is different than for a -6...at least the fuselage attachment area.
 
Ron Lee said:
In the case of N424D, perhaps the two fatalities will place this higher on the NTSB priority list.
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Unfortunately, that's unlikely to be the case. I understand that the NTSB is overloaded with opportunities and understaffed, as the TSB is here in Canada. As such, they will focus on investigations that are likely to yield the greatest benefit to the greatest number of people. For the most part, that means the 777 that crashed killing everyone on board, not the one experimental aircraft that represents 1/3 of the total population of that type... And by type, I mean Chard-6's, not Vans RV's. Even if they investigated the crash of AC-3, and learned that it was a structural issue, that knowledge would only benefit two other aircraft owners.

That being said, if there haven't been any major commercial incidents in the area recently, they may have the bandwidth for a more thorough look.

Something i've been wondering about for a while is whether it would be possible or even practical to set up a network of "amateur investigators" to look into amateur-built aircraft accidents. I have offered my engineering and aviation knowledge as a resource to the TSB here in Canada and have assisted with two accident investigations when the TSB didn't have the bandwidth to do the work themselves. I did it on a volunteer basis, because it wouldn't have happened otherwise. Has anyone in the US tried this?
 
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Yes, ALPA has.

Snowflake;721196 Something i've been wondering about for a while is whether it would be possible or even practical to set up a network of "amateur investigators" to look into amateur-built aircraft accidents. Has anyone in the US tried this?[/QUOTE said:
ALPA (Air Line Pilots Association) has its own investigators and school:

http://fdx.alpa.org/LinkClick.aspx?fileticket=A7pjil/T4zw=&tabid=3202

Advanced course:

http://fdx.alpa.org/LinkClick.aspx?fileticket=Tnh6ziR9FdA=&tabid=3202
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Wing spar - RV-8 comments

The RV-8 structural failure alluded to was extensively investigated by both NTSB and Vans. Vans proceeded to do sophisticated flutter testing by recognized experts (not just Vans staff) and then tested a sacrificial wing to failure. These tests are documented in old RVators and showed: 1) The flutter margins for the RV-8 are very adequate and; 2) the wing structure easily met its design load factors. Interesting that when loaded to failure the structure held well over 9 G's. Failure IIRC occurred not at the wing root but near the outboard end of the flap. As suggested earlier, the spar structures of the -6 and -8 are completely different as are the mating to the fuselage. Looking at this area on a -8 gives a feeling that the overlap between the wing spar and the fuselage section is not enough, but it clearly works well - just ask Ironflight!
 
Bill Dicus said:
Looking at this area on a -8 gives a feeling that the overlap between the wing spar and the fuselage section is not enough, but it clearly works well - just ask Ironflight!
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I don't recall the overlap on the -8 but was surprised at what seemed a relatively small overlap on the -9, particularly considering the longer wing. I thought the wing portion that inserts into the carry-through would be at least twice as long....but I'm no expert!
 
LDJones said:
I don't recall the overlap on the -8 but was surprised at what seemed a relatively small overlap on the -9, particularly considering the longer wing. I thought the wing portion that inserts into the carry-through would be at least twice as long....but I'm no expert!
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I am not a structural design engineer, but I can tell you that the RV-1 had NO overlap (other than the sockets that holds the taper pins that hold the main wing spars to the fuselage) - and Van flew the heck out of that thing years ago - plenty of aerobatics. Overlap by itself isn't a good indicator of if it is srong enough - but of course, on the -3 (and the -6), the spar stubs go all the way to the center of the fuelage, and have steel splice plates. Very beefy!
 
I have Art's second, what he called RV6, S/N AC-2. It was a concept plane, I think, more than a prototype.

It was built in 1980, well before the RV-6 kits came out. I have been sent pictures of AC-3 and it looks different than mine. It was built 16 years later, when the kits had been out a long time. I understand it was scratch built, but don't know from what plans.

I can tell you that my wing spars meet stubbed together in the middle and bolted together with thick steel plates. The rear spar was modified in 1997 by Art's design, I believe, with a doubler plate at the wing root.
 
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Rockman said:
I have Art's second, what he called RV6, S/N AC-2. It was a concept plane, I think, more than a prototype.

It was built in 1980, well before the RV-6 kits came out. I have been sent pictures of AC-3 and it looks different than mine. It was built 16 years later, when the kits had been out a long time. I understand it was scratch built, but don't know from what plans.

I can tell you that my wing spars meet stubbed together in the middle and bolted together with thick steel plates. The rear spar was modified in 1997 by Art's design, I believe, with a doubler plate at the wing root.
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Can you post pictures of your AC-2?
 
Parts of the aircraft in question were purchased from Art. It is my understanding that the wings were RV-4, with a modified RV-6 fuselage and Continental engine. It was used as a non-aerobatic cross country aircraft.
 
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