Ground Vibration Tests 601xl

[Thruster87]

The results of the German-led GVT (Ground Vibration Tests) are in and they are unequivocal: The Zodiac CH 601 XL and CH 650 E are not subject to flutter if built, maintained and flown as intended by Zenair. The linear flutter tests confirmed this for all speeds up to 400 km/h and with aileron control cable tension down to less than ten pounds.:thumb_up:

 

 

[Guest pelorus32]

G'day Thruster,

 

do you have a reference to the source of this please?

 

Regards

 

Mike

 

 

[Thruster87]

Hi Mike, it was on the matronics site and Zenair Europe News Index

 

 

[Thruster87]

The recent meetings between Zenair and German authorities (the DAeC and their DAR engineers as well as the BFU) were very productive with key steps taken towards re-establishing the good standing of the CH 601 XL aircraft throughout Europe. A very comprehensive presentation by the head of the GVT program that tested the aircraft made it very clear that the oft suggested flutter is an exceedingly unlikely "smoking gun" to explain past accidents. The engineer in charge instead applauded Chris Heintz for the overall scores obtained by the Zodiac throughout the tests, as they were among the best ever seen in his lab. The results of the very thorough linear flutter analysis left no doubts in anyone's mind: "No tendency to flutter or divergence was found within the flight envelope of the CH 601 XL". This included tests from minimum to maximum take-off weight; with fixed as well as free controls; with control cable tensions varying from well below 10 lbs. to over 40 lbs, and with standard as well as overweight control surfaces (i.e. possibly due to excessive paint in the "real world"); all from sea level to over 15,000 feet and to speeds well above 400 km/h.

 

In order to ensure accurate results, all tests were carried out on two different Zodiac aircraft. The significance of the flap stops called-for as part of the regular design was confirmed. The aircraft which did not at first have these installed showed less satisfactory results than Zenair's own standard demo plane (with stops) which was one of the tested planes. Zenair will be issuing a Service Letter very shortly calling for owners/pilots to check their flap stops (and to install them prior to further flight operations if these have not been previously fitted). By the end of the tests, both aircraft (a classic CH 601 XL and the newer CH 650 E) presented the same consistent results: No tendency to flutter.

 

Also during this GVT testing process, it was noticed that the German-registered CH 601 XL on which the tests were conducted did not have part of the aileron-stop structure which was an integral part of the CH 601 XL at the time of German certification. Zenair has been asked by the DAeC to issue a Service Letter addressing this potential discrepancy for German-registered CH 601 XL; the DAeC will be issuing its own AD shortly to ensure the aircraft's ongoing compliance with LTF-UL certification.

 

Many questions were answered by the flutter expert after his presentation to German authorities; his answers and ample GVT data successfully satisfied those present that flutter was a non-issue for the Zenair Zodiac design. "The complete ground vibration tests (GVT) just completed were conducted to natural frequencies well over 70 Hz. This clearly demonstrates that the standard Zodiac design is flutter-free within (and well beyond) the entire range of its flight envelope" said Chris Heintz, who also attended the meetings.

 

 

[yharry]

good news for zenith owners and buyers.

 

it will be interesting to see what NTSB USA thinks of this.

 

there are four quick build kits in stock at Sport Air Services, i hope this news reassures the new builders and these kits get snapped up.

 

 

[Thruster87]

FULL TEST RESULTS http://www.zenairulm.com/FAQ/pdfdocs/CH601XL-GVT-June6.pdf