Recommendation Affects Approximately 400 Airbus Planes
On Friday, the National
Transportation Safety Board urged the Federal Aviation
Administration to order inspections of the inner skin of the
composite rudder surfaces of certain Airbus A300 series
The safety recommendations -- one of which is classified as
urgent by the Safety Board -- address a safety issue identified
during the investigation of damage found during an inspection of a
rudder from a Federal Express A300-600 airplane last November. The
Board noted that this incident might have applicability to a more
serious rudder separation that occurred last year, involving a
"The Board believes that this urgent recommendation, if acted
upon quickly, will go a long way to prevent a catastrophic failure
of the rudder," NTSB Acting Chairman Mark V. Rosenker said.
On March 6, 2005, an Airbus A310-300,
operated by Air Transat as flight 961, experienced an in-flight
separation of its rudder shortly after departure from Juan G. Gomez
International Airport in Varadero, Cuba. The flight
returned to Varadero, where it landed uneventfully. Upon landing,
the crew discovered that most of the airplane's rudder had
separated in flight with only the bottom closing rib and the spar
between the rib and the hydraulic actuators remaining.
Following the Air Transat accident -- which is being
investigated by Canada with the assistance of the NTSB -- Airbus
issued a mandatory All Operator Telex (AOT) A300-55A6035 specifying
a one-time rudder inspection for all A-300 series airplanes
equipped with premodification 8827 or 40904 rudders. On March 28,
2005, the FAA issued Airworthiness Directive (AD) 2005-07,
requiring operators to perform the inspections specified in the
AOT. American Airlines and Federal Express (the only U.S. operators
of these airplanes) complied with the AD.
On November 27, 2005, the rudder on an Airbus A300-600 airplane
operated by Federal Express was damaged during routine maintenance.
To assess the extent of the damage, the rudder was shipped to the
manufacturer's facility and examined. In addition to the damage
that occurred during maintenance, the examination found a
substantial area of disbonding between the inner skin of the
composite rudder surface and the honeycomb core, which is located
between two composite skins.
Further examination of the disbonded area revealed traces of
hydraulic fluid. Hydraulic fluid contamination between the
honeycomb skin and the fiberglass composite skin can lead to
progressive disbonding, which compromises the strength of the
rudder. Tests on the damaged rudder also revealed that disbonding
damage could spread during flight.
The investigation found that the areas specified in the AOT did
not include the areas in which the disbonds were found on the
incident rudder. Further, it was determined that tap tests on the
external surfaces of the rudder likely would not have disclosed the
disbonding of an internal surface.
On March 2, 2006 Airbus issued AOTs notifying operators of
applicable A300 series airplanes that large disbonds between the
rudder's inner skin and the honeycomb core could go undetected, and
providing guidance for inspecting the rudders. The Safety Board is
recommending a more stringent compliance time than specified in the
AOT and also requesting that FAA make the inspections
More recent examinations have disclosed that hydraulic fluid can
exist along the edges of the rudder's inner surface along with an
accompanying area of substantial disbonding and that the inspection
specified in the AOTs cannot detect the presence of the hydraulic
fluid or the disbonding along the edges.
Therefore, the Safety Board is recommending that the FAA require
that all operators of Airbus A-300 series airplanes immediately
(possibly before further flight) comply with four Airbus All
Operators Telexes dated March 2, 2006. Any disbonding to the rudder
skins that occurs in the presence of hydraulic fluid contamination
should be repaired or the rudder should be replaced as soon as
possible, well before the 2, 500 flights specified in the AOTs.
(A-06-27) This is an urgent recommendation.
The NTSB further recommended that the FAA establish a repetitive
inspection interval for Airbus premodification 8827 rudders until a
terminating action is developed. The interval should be well below
2,500 flights. (A-06-28)
It is estimated that these recommendations concern about 400
aircraft in Airbus's worldwide fleet.