| AMD Zodiac | |
|---|---|
| Zenair CH 601 XL with Continental O-200 engine | |
| Role | Kit aircraft |
| Manufacturer | Aircraft Manufacturing and Design |
| Designer | Chris Heintz |
| Introduction | 1984 |
| Retired | N/A |
| Status | in production |
| Primary users | recreational pilots/sport pilots private pilots |
| Produced | Eastman, Georgia |
| Number built | More than 1,000 |
| Unit cost | US$18,500 (kit only, December 2011)[1] |
The Zodiac is a family of Canadian all-metal, two-seat, fixed landing gear airplanes that first flew in 1984. The aircraft have been produced as kits and completed aircraft by Zenair in Canada and Zenith Aircraft Company in the USA.[1][2]
The latest models in the Zodiac family are the ready-to-fly AMD Zodiac LS and LSi produced by Aircraft Manufacturing and Design.[3] The design has a single-piece bubble canopy.
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The original Zodiac airplane was designed in the mid-eighties, by Chris Heintz. It started out as a kit plane, meaning that consumers can purchase the plane as components to assemble it themselves.[3] The Zodiac has since been manufactured in Canada, Europe, USA and South America as a factory-assembled, ready-to-fly aircraft.[3]
Heintz drafted the regulations for light-sport aircraft in Canada around the time he designed the Zodiac. He also played an important role in drafting the current light-sport aircraft (LSA) rules for the United States.
Zenith Aircraft Company still produces kits and Quick-build kits for the Zodiac kit for the homebuilt-market.[4]
In the Netherlands, the Dutch government grounded the 12 Dutch-registered CH 601 XLs on 24 October 2008. The planes were banned from flying pending an investigation into their structural strength, following the crash of a European variant of the design (Rotax powered and 450 kg (992 lb) maximum take-off weight) that killed two people. According to the Dutch government, since 2005 "at least seven accidents with Zenith CH601 XL's have happened in which one or both wings have failed".[5] Zenair Europe investigated these accidents,[6] concluded that none are due to a design defect and, after a first-hand review of the wreckage, also rejected suggestions that the aircraft in the Dutch accident experienced a structural failure.[7]
On 14 April 2009, the NTSB wrote an urgent letter to the FAA recommending that they ground all Zodiac CH 601 XLs, saying "It appears that aerodynamic flutter is the likely source of four of the U.S. accidents and of at least two foreign accidents".[8] The NTSB also wrote to ASTM International, the body responsible for developing standards for light sport aircraft, recommending that those standards be changed in light of the investigation. The NTSB says that the type has been involved "in six in-flight structural breakups since 2006".[8][9][10][11][12]
Zenith Aircraft disputed the NTSB's conclusions and stated in a response on their website that "[w]e continue to believe wing flutter will not occur if the control cables are adjusted properly."[13] They also cited Zenair Europe's disagreement with the Dutch government's conclusion that that accident was caused by flutter. AMD issued a safety alert in October 2008 mandating inspections of aileron control cable tensions.[14] The company hired an independent consultant, Dr. Uwe Weltin, an internationally recognized flutter and vibrations specialist and head of the Institut für Zuverlaessigkeitstechnik at the Technical University of Hamburg-Harburg who concluded that when the CH 601 XL is built and maintained to Zenair specifications, there is "no tendency to flutter or divergence found within the flight envelope of the CH 601 XL". The company claimed that the report clears the Zodiac design of flutter-related concerns as long as CH 601 XL is built and maintained to Zenair specifications.[15]
In reacting to the NTSB recommendations the FAA Administrator Randy Babbit declined to ground the aircraft and in a 13 July 2009 letter, stated "Data indicates the CH-601XL has a safety record similar to other S-LSA and appears capable of safe flight and operations if maintained according to the manufacturer’s recommendations."[16]
On 6 November 2009 an amateur-built CH-601XL broke up in flight over Arkansas, resulting in the death of the pilot. Preliminary investigation of the accident revealed a failure mode similar to that seen in the earlier crashes, as both wings separated in flight. This brought the number of crashes to seven and deaths to 11.[17][18]
The FAA issued a Special Airworthiness Information Bulletin on 7 November 2009 and strongly recommended that the aircraft not be flown until modifications detailed in an AMD Safety Alert are carried out. AMD and Zenith Aircraft issued documents the same day, mandating that the S-LSA version not be flown until the modifications were completed and recommended all aircraft be modified. The modifications included strengthening of the main and rear wing spar carrythroughs and the addition of aileron balance weights. The Experimental Aircraft Association also recommended grounding all affected aircraft until modifications are complete.[19][20][21][22][23]
In a statement issued by Zenith Aircraft, the designer, Chris Heintz in response to the question "Why are you recommending this Upgrade Package? What has prompted this "180- degree" shift, from insisting that the CH 601 XL design was fine "as is", to now mandating a list of upgrades requiring more than a dozen modifications?" stated:
| “ | The past two years have been challenging for the CH 601 XL community around the world. As we all know, a number of accidents have occurred over the span of a few years for which no common cause has been determined. This lack of a "smoking gun" has caused all kinds of conjectures and wild guesses as to probable cause, and each time a new "theory" or "solution" is proposed, I and numerous engineers spend long hours trying to validate or rebuke the latest round of speculation. To this date, after thousands of man-hours of investigations, multiple design reviews and an unheard-of amount of testing, the accidents in question still do not share a common cause. In offering this “Upgrade Package” I have had to set aside my own professional opinion (that the design is sound) as well as legal counsel’s advice in order to provide builders, owners and pilots the “fix” that they have been asking me for. With these upgrades (my "180° shift"), the safety margins of key airframe components have been dramatically increased...[24] | ” |
On 12 November 2009 the FAA ceased issuing new Certificates of Airworthiness, requiring new registrants to prove that they have complied with the modifications before being permitted to fly the aircraft.[18]
In addressing the 6 November 2009 accident NTSB Chairman Deborah A.P. Hersman said on 13 November 2009:
| “ | 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 no modifications are required on the amateur-built planes. 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.[17] | ” |
The FAA completed an in-depth review of the CH601 XL and 650 and issued a report entitled Zodiac CH601 XL Airplane Special Review Team Report January 2010. The FAA concluded:[25][26]
| “ | FAA review of the in-flight failures did not indicate a single root cause, but instead implicated the potential combination of several design and operation aspects. Our preliminary assessments focused on the strength and stability of the wing structure. Further analysis during the special review found the loads the manufacturer used to design the structure do not meet the design standards for a 1,320 lb (600kg) airplane. Static load test data verifies our conclusion. The special review also identified issues with the airplane’s flutter characteristics, stick force gradients, airspeed calibration, and operating limitations.[25] | ” |
In reacting to the FAA's report the Experimental Aircraft Association's Vice President of Industry and Regulatory Affairs, Earl Lawrence, said, "The FAA did an excellent job with this investigation and deserves credit for thoroughly exploring all possibilities. EAA had vigorously pushed for comprehensive data on these accidents. We wanted to see the data, so aircraft owners knew exactly what modifications were needed and why they were needed immediately."[27]
There are over 1000 Zodiac aircraft flying worldwide.[3]
Data from AMD website[3]
General characteristics
Performance
Avionics
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