craig(at)craigandjean.com
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 Posted: Tue Nov 11, 2008 8:01 pm Post subject: Nov 7th and 9th updates on Zenith European groundings |
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Nov 7th:
"For many owners of the presently grounded CH 601 XL in Europe, evidence of
progress with the current investigation has been disappointingly slim for
the last week. This is also the case for Zenair Europe. The response from
Dutch authorities to our repeated inquiries has been consistent: "The
investigation is on-going". Our offer to provide input has been politely
declined, as has our request to inspect the accident aircraft, as has our
offer to fly designer Chris Heintz to Holland to answer engineering
questions. Other Civilian Aviation Authorities (CAA) have also attempted to
obtain additional details, to no avail.
Adding to the frustration: Due to the complete lack of information being
released, even between agencies, the CAA of a number of additional countries
have felt compelled to adopt the Dutch "emergency" action: To our knowledge,
the Czech Republic, Greece and Spain all grounded their CH 601 XL fleets
this week. A number of offices we are in contact with regret at having to
ground the aircraft, but until the Dutch Safety Board reveals the basis for
its allegation that the "design calculations by the designer were probably
too optimistic", they have little choice but to err on the side of caution.
Another unexpected twist this week came from the UK: In the UK, where the
CH 601 XL is considered an Experimental amateur-built design (it is not a
certified ultralight there like in the rest of Europe), the LAA did not feel
that grounding the aircraft was justified based on the available information
from the Netherlands (see our update of October 30). Now aware, however,
(via our bulletin #ZE-2008-001) that aileron flutter is a remote possibility
if control cables are loose, the LAA has grounded the XL fleet in the UK
until it has been demonstrated that the aircraft will remain flutter-free
throughout the range of its flight envelope, even with cable tensions set at
their lowest approved tolerances.
In the original rational which accompanies their "Emergency Airworthiness
Directive" (grounding), Dutch authorities cite "seven similar accidents
worldwide that have not been explained" [paraphrased]. A number of builders
have pointed out the inaccuracy of this claim as well as the absurdity of
using it to justify the current grounding. Zenair has tried to convey this
message and hopes that it was heard. We thank Dutch CH 601 XL owner and
pilot Hans Oosterhoff for researching these accidents and for sending us a
summary of his findings; it will be included in our next update."
The Nov 9th update nicely summarizes many of the accidents around the world.
One twist I didn't know about the crash in Spain:
"Accident in Spain (05/02/2008): According to eyewitnesses, wing fractured
after an explosion. Additional context from Zenair dealer in Spain: accident
occurred after a high-speed pass and pull-up over a football field where a
family member of passenger was playing. Based on findings, Accident
Investigation Committee estimated high speed pass of approx. 290 Km/h*.
(Source: http://www.ultraligero.net/Accidentes/08.htm and Zenair
correspondence) (CZAW-ULM) *Note: VNE = 260km/h"
By my calculations 290 Km/h would be 180.1 mph.
-- Craig
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