Friday, November 13, 2009

Grounding the Zodiac CH-601XL

The relationship between the National Transportation Safety Board and the Federal Aviation Administration has always been rocky. The NTSB staff thinks the FAA ignores their "suggestions."

Today, a news release practically says it out loud. Here's the release:

An experimental airplane of the same series that the National Transportation Safety Board urged the Federal Aviation Administration to ground seven months ago, until a
flight control problem could be corrected, was involved in another fatal accident last week.

On November 6, 2009, a Zodiac CH-601XL, an experimental amateur-built airplane, was destroyed as a result of an in-flight breakup near Agnos, Arkansas, killing the pilot who was the sole occupant. The debris field was scattered over an area more than 600 feet long. Both wings had separated from the fuselage in-flight.

In April 2009, the NTSB called on the FAA to ground the Zodiac CH-601XL after the Safety Board linked six accidents involving that aircraft model to aerodynamic flutter, a phenomenon in which the control surfaces and wings of the airplane can suddenly oscillate and lead to catastrophic structural failure. Those accidents killed a total of ten people. Preliminary investigation of the November 6 accident
in Arkansas reveals a failure mode similar to that seen in the earlier crashes.

The Safety Board's urgent recommendation to the FAA was to "prohibit further flight of the Zodiac CH-601XL, both special light sport aircraft and experimental, until such time that the FAA determines that the CH-601XL has adequate protection from flutter." The FAA replied in July that they lacked "adequate justification to take immediate certificate action to ground the entire fleet."

The Zodiac is available as a ready-to-purchase airplane (classified as a special light sport aircraft), which is manufactured by Aircraft Manufacturing and Design, LLC, and as an amateur-built plane from a kit (classified as an experimental aircraft) available from the designer, Zenith Aircraft Company.

On November 7, one day after the accident in Arkansas, the FAA issued a Special Airworthiness Information Bulletin strongly recommending that all owners and operators of Zodiac CH-601XL/CH650 airplanes comply with a Safety Alert/Safety Directive issued by the manufacturer, Aircraft Manufacturing and Design, LLC. The Safety Alert/Safety Directive requires all owners of special light sport aircraft models to make structural modifications to the airplane and add aileron couunter-balances before further flight. Since the directives of the manufacturers of special light sport aircraft must be complied with, those aircraft not in compliance are effectively prohibited from further flight.

The designer, Zenith Aircraft Company, has asked the owners of the kit-built experimental airplanes to make the same modifications, but there is no requirement that the modifications be completed before further flight is attempted.

"We are pleased that the FAA and the manufacturer have acted on the safety-of-flight issues that we identified with the Zodiac special light sport airplane. We are troubled, however, that the no modifications are required on the amateur-built planes," said NTSB Chairman Deborah A.P. Hersman. "We are very concerned that a lack of required compliance may lead to more accidents like the one in Arkansas, and others we've already seen," she said.

The Safety Board's investigation of the November 6 accident is on-going.

In the various conversations that took place surrounding my post about the inability to make a first flight out of South St. Paul Airport, most people -- and rightly so -- said it was a fair prohibition as a crash would negatively impact the perception of homebuilt airplanes.

For that reason, all homebuilders should be pressuring the FAA to act more forcefully in grounding the CH601XL.


  1. Dear Bob

    Thanks for your newsletters and blogs. They've
    been useful, and I read them often.

    The topic of your posting on the CH601 flutter issue brings to mind the terrifically complex semantic implications of the Fox News slogan: "Fair and Balanced". No, I'm not associating you with any particular political or philosophical standpoint: My intention is to observe that there is a huge regulatory elephant behind any new FAA regulatory initiative, and perception of 'fairness and balance' in regulation is very much affected by one's point of view.

    The existence of experimental amateur-built aviation is a really remarkable phenomenon. Permitting this activity presents a balancing act: Let a bunch of individualists take care of themselves, while taking reasonable policy precautions to keep those non-professional experimenters from endangering the rest of a society that seeks absolute protection. The actions of government are rarely performed with surgical precision, and to everyone's satisfaction: An FAA that takes increased responsibility for product safety in experimental aircraft, I think, could mean the end of ABAM aircraft. Would you, as a responsible FAA bureaucrat (not meant pejoratively), want to be responsible for safety without having authority over the entire product? How could you do your job without having control over design, documentation, and quality assurance for all parts and processes?

    There is an obvious conflict in the matter of amateur expermimental aviation versus "FAA acting more forcefully" in grounding an experimental aircraft. If we are going to have an opportunity to pursue experimental aviaiton in which there is not a Government-operated or supervised professional certification and engineering review process, then we will need to continue to prevent and solve deficiencies by ourselves. Note that 'ourselves' doesn't have to be "yourself, alone": The advent of aircraft kits has bolstered safety by producing shared user experience regarding improvements and limitations.

    I suppose that the present issue with Zenair control flutter will result in a changed insurance situation for those aircraft. If I were an insurance company, I would require an owner's statement that an airplane covered by my insurance product has been brought into compliance with the designer's current specifications for assembly and rigging. No compliance would mean no insurance.

    Closure of some airports to initial flights and phase 1 testing of experimental airplanes is a predictable effect of the assignment of responsibility for public safety to a government employee. That earnest and hard-working government employee who restricts you from phase 1 flight testing is taking almost exactly the kind of action that you suggest should be taken in the Zenair matter: He's taking it in the absence of a specific concern, and he's taking it in advance instead of in response to an incident, but, it seems to me that the philosophical path is very similar.

    This topic suggests a long excursion (maybe at a flyin sometime...) into questions about whether or not you and I are making informed decisions about our aircraft experimentation, into the tensions between individuality (our Right to go out and screw up) and society's interest in minimizing screw-ups, and all that.

    At present, I disagree with your call for an FAA crackdown on CH601 implementation. This is a job for the kit vendor, builders, and (maybe) insurers, in which action should be taken quickly.

    Best regards

    Mike Linse, RV-6A builder, Corvallis, Oregon

  2. Bob,
    I wholeheartedly agree with Mr. Linse. The last thing we need is the Feds issuing willy-nilly A.D.s against our E-AB aircraft. The RV-3 is a good example of how it should work. There were structural failures that were addressed by Van's in the form of structural mods. Some owners elected to ignore the fix and at least one suffered an inflight breakup after the mods were announced. The FAA took no further action because the owner had the sole responsibility as to the airworthiness of the aircraft. People are leaving the ranks of certificated aircraft ownership in droves because of the FAA and it's CYA attitude driving the cost of ownership through the roof.


    Mike Hilger, RV-6 (900 hours!), EAA Tech Counselor, KSGS

  3. Aha! You have both fallen into my wily trap! I was actually pointing out the inconsistency in favoring one form of regulation/government intervention to protect the image of experimental aviation on one hand (limiting first flights from an airport) while disagreeing with it for another.

    Of course since I don't know your opinions on restricting first flights, you were unwitting pawns.

    Bwaaa haaa haaaa. (g)

  4. Mike Linse again...

    I was pointing out that inconsistency too.

    As for my opinion about first flights:
    I'm certainly looking forward to mine!
    First flights are a necessary step, and, in a way, they happen after every annual of every airplane.

    I'd be interested to know what you would find if you turned your journalistic attention to the question of just how common dangerous "issues" actually are in first flights of ABAM aircraft? I've been reading various groups such as the RV List and Van's Airforce for about ten years, and the common first flight complaints are heavy aileron, excessive oil or cylinder head temperature, etc. Although I'm sure that an incident has probably happened in a first flight, I cannot remember one as I'm writing this. My attention to this issue has been primarily in the context of RVs. There certainly have been fuel, flight control, electrical, and lubrication problems in regular and post-inspection flights of certified aircraft. The EAA might be a useful source on this subject. Perhaps this review would serve your situation with regard to first flight and phase 1 testing: It's pretty likely that you can show evidence to the effect that the public risk involved in your first flight is miniscule. A ban on such operations seems to be an excessive response on the part of your airport's manager.

    Mike Linse, RV-6A builder, Corvallis, Oregon

  5. I don't know if you read the VAF thread a few weeks ago that I started regarding the KSGS situation but that's exactly the information I've been trying to find, especially from the DARs on that board. But every time I asked it, the subject got redirected, so my suspicion is that policy has been set -- at least at the DAR level (which seems to be where the FAA wants it to be set, I guess) -- with nobody having any idea what the data is.

    In my case -- just to be clear -- the airport manager has nothing to do with the situation. It's the DARs and, by extension, the FAA.

    Even the Twin Cities RV Builder's Group seems generall satisfied with the first flight restrictions, but they don't seem to have the data either.

    I'm going to query the EAA. I suspect they don't have it either.

  6. You're talking "apples and oranges" here, Bob. The people restricting the test area are from the Operations side of the FAA. The DAR's don't set first-flight and/or Phase I testing restrictions. The Ops people at the FSDO do that. The DAR coordinates with the FSDO and when he sets your testing area and restrictions he is complying with their wishes. The people that create and enforce airworthiness regs and A.D.s are the Maintenance or Airworthiness group. We are always going to be subject to the Ops side because we operate in the same airspace as type-certificated aircraft. There has, however, been minimal involvement by the Airworthiness people (ELT's and ELT testing, transponder checks, etc.) and most of us want to keep it that way.

    Mike Hilger