AMD Zodiac: Wikis


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AMD Zodiac
Zenair CH 601 XL with Continental O-200 engine
Role Kit aircraft
Manufacturer Aircraft Manufacturing and Design
Designed by Chris Heintz
Introduced 1984
Retired N/A
Status in production, grounded for modifications by FAA
Primary users recreational pilots/sport pilots
private pilots
Produced Eastman, Georgia
Unit cost $84,900-94,900
Zenair CH 601 HDS Zodiac

The Zodiac is a Canadian all-metal, two-seat, fixed tricycle gear airplane that first flew in 1984. The original CH 600 has evolved into a complete family of light aircraft including the 601 HD, 601 HDS and the 601 UL. The aircraft have been produced as kits and completed aircraft by Zenair in Canada and Zenith Aircraft Company in the USA.[1]

The latest models in the Zodiac family are the ready-to-fly AMD Zodiac XL and XLi produced by Aircraft Manufacturing and Design.[2] The design has a single-piece bubble canopy.



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.[2] The Zodiac has since been manufactured in Canada, Europe, USA and South America as a factory-assembled, ready-to-fly aircraft.[2]

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.[3]

Flutter and grounding

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 MTOW) 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".[4] Zenair Europe investigated these accidents [5], 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.[6]

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"[7]. 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".[7][8][9][10][11]

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."[12] 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.[13] 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.[14].

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."[15]

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.[16][17]

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.[18][19][20][21][22]

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...[23]

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.[17]

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.[16]

Operational history

Jay Maynard and his 2008 AMD Zodiac CH601XLi

A CH-601 XLi is owned and flown by Jay Maynard.[24]



Zenair CH 600

The original version of the Zodiac, the CH 600, was designed by Chris Heintz and first flown in 1984. The aircraft was intended as a primary trainer.[1]

Zenair CH 601 HD

The CH 601 HD (for heavy duty) was the follow-on to the original CH 600 and incorporated many improvements to the design. The HD version had a gross weight of 1200 lbs and a standard empty weight of 530 lbs. Aircraft kits were marketed by Zenair of Midland, Ontario in Canada and by Zenith Aircraft of Mexico, Missouri.[25]

Zenair CH 601 HDS

The CH 601 HDS (for heavy duty speedwing) was a version of the HD with the wing span is reduced to 23 feet and a wing area of just 98 square feet. The wing also featured a tapered design with a 34 inch chord at the wing tip.[26]

Zenair CH 601 UL

The UL version of the CH 601 was specially designed for the Canadian Advanced Ultralight Aeroplane category that was introduced in 1991. Heintz was instrumental in the creation of the category as the author of the standards and used the CH 601 as a model for the category. The UL version had a reduced gross weight of 1058 lbs, the maximum allowed in the category. When the gross weight for the AULA category was increased to 1200 lbs in 2001 the CH 601 UL had its gross weight increased to the 1200 lb mark also. The UL version was supplied in 51% or 85% kit or completed form by Zenair in Canada and was designed for engines of 80-100 horsepower. The aircraft did not neatly fit any US categories and US buyers were advised to consider the HD instead.[25][27][28]

Zenith CH601 XL

The CH 601 XL was first flown in 1991 as an improved version of the HD developed for the amateur-built market and also for the American Light Sport Aircraft category. The XL features many incremental improvements over the HD, including a new wing design, wing fuel tanks to replace the fuselage tanks of the HD, new landing gear design and a new canopy.[25][3]

AMD Zodiac XL & XLi

The completed US Light Sport Aircraft compliant version of the XL is the AMD Zodiac produced by Aircraft Manufacturing and Design of Eastman, Georgia, USA. The aircraft is available in two versions, the XL, and the XLi. The XLi is IFR equipped for night flying and instrument flight conditions, while the XL is only equipped for VFR day and night flying.[2]


There are over 1000 Zodiac aircraft flying worldwide.[2]

Specifications (AMD Zodiac XL)

Data from AMD website[2]

General characteristics

  • Crew: 1 pilot
  • Capacity: 1 passenger
  • Length: 20 ft (6.1 m)
  • Wingspan: 27 ft (8.23 m)
  • Height: 78 in (1.98 m)
  • Wing area: 132 ft² (12.5 m²)
  • Airfoil: NACA 65-018[29]
  • Empty weight: 770 lb (350 kg)
  • Loaded weight: 1320 lb (600 kg)
  • Useful load: 550 lb (250 kg)
  • Max takeoff weight: lb (kg)




  1. ^ a b Zenith Aircraft Company (November 2006). "ZODIAC CH 601 HD". Retrieved 2008-03-01.  
  2. ^ a b c d e f Aircraft Manufacturing & Design (February 2008). "Zodiac XLi". Retrieved 2008-02-23.  
  3. ^ a b Zenith Aircraft Company (February 2008). "ZODIAC XL". Retrieved 2008-03-01.  
  4. ^ Inspectie houdt twaalf sportvliegtuigjes aan de grond (in Dutch)
  5. ^ Zenair Europe News
  6. ^ Zenair Europe News
  7. ^ a b National Transportation Safety Board (April 2009). "Safety Recommendation". Retrieved 2009-04-15.  
  8. ^ CNN news story on NTSB letter
  9. ^ NTSB letter to ASTM
  10. ^ National Transportation Safety Board (April 2009). "NTSB ASKS FAA TO ‘PROHIBIT FURTHER FLIGHT’ OF LIGHT SPORT AIRPLANE TIED TO IN-FLIGHT BREAKUPS". Retrieved 2009-04-15.  
  11. ^ Lowy, Joan (April 2009). "NTSB: Light sport plane can break apart in flight". Retrieved 2009-04-15.  
  12. ^ Zenith Aircraft Company (April 2009). "News from Zenith Aircraft Company". Retrieved 2009-04-15.  
  13. ^ Aircraft Manufacturing & Design, LLC (October 2008). "AMD Safety Alert, October 29, 2008". Retrieved 2009-04-15.  
  14. ^ Zenair Europe (July 2009). "". Retrieved 2009-07-03.  
  15. ^ Zenith Aircraft (August 2009). "Zodiac CH 601 XL / CH 650 update – July 27, 2009". Retrieved 2009-08-08.  
  16. ^ a b National Transportation Safety Board (November 2009). "AIRPLANE TYPE NTSB RECOMMENDED TO BE GROUNDED INVOLVED IN ANOTHER FATAL ACCIDENT". Retrieved 2009-11-14.  
  17. ^ a b Pew, Glenn (November 2009). "New Zodiac In-Flight Break-up Shows FAA/NTSB Rift". Retrieved 2009-11-16.  
  18. ^ Federal Aviation Administration (November 2009). "Special Airworthiness Information Bulletin CE-10-08". Retrieved 2009-11-09.  
  19. ^ Aircraft Manufacturing & Design, LLC (November 2009). "AMD Safety Alert - Directive, November 7, 2009". Retrieved 2009-11-09.  
  20. ^ Pew, Glenn (November 2009). "EAA Recommends Grounding Zodiacs Until Fixed". Retrieved 2009-11-10.  
  21. ^ Experimental Aircraft Association (November 2009). "FAA Issues Special Airworthiness Information Bulletin on Zodiac CH601XL and CH650 Aircraft". Retrieved 2009-11-10.  
  22. ^ Zenith Aircraft (November 2009). "FAA Issues Special Airworthiness Information Bulletin CE-10-08 (Nov. 7, 2009): Zodiac CH601 XL". Retrieved 2009-11-10.  
  23. ^ Zenith Aircraft (November 2009). "Q&A with Chris Heintz". Retrieved 2009-11-10.  
  24. ^ Maynard, Jay. (undated). "Jay's airplane". Retrieved 2009-11-09.  
  25. ^ a b c Kitplanes Staff: 1999 Kit Aircraft Directory, page 76. Primedia Publications, December 1998.
  26. ^ Zenith Aircraft Company (May 2004). "ZODIAC CH 601 HDS". Retrieved 2008-03-01.  
  27. ^ Canadian Owners and Pilots Association: COPA Guide to Ultralights 10th Edition, October 2006, pages 9-10. Canadian Owners and Pilots Association
  28. ^ Zenith Aircraft Company (May 2002). "ZODIAC CH 601 UL". Retrieved 2008-03-01.  
  29. ^ Lednicer, David (October 2007). "The Incomplete Guide to Airfoil Usage". Retrieved 2008-03-01.  

External links


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