NTSB -- AIRPLANE TYPE NTSB RECOMMENDED TO BE GROUNDED INVOLVED IN ANOTHER FATAL ACCIDENT

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NTSB ADVISORY

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National Transportation Safety Board

Washington, DC 20594

November 13, 2009

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AIRPLANE TYPE NTSB RECOMMENDED TO BE GROUNDED INVOLVED IN

ANOTHER FATAL ACCIDENT

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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 counter-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.

Related press release including links to the safety

recommendations referenced above:

http://www.ntsb.gov/Pressrel/2009/090414a.html

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NTSB Media Contact: Peter Knudson

peter.knudson@xxxxxxxx

(202) 314-6100

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