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Washington, DC (April 15, 2002) NTSB Chair urges study on aircraft composite "wear-out", wants more money to hire composite engineers. NTSB also looking into uncommanded rudder incident on Singapore Airlines A340 two weeks after AA 587 crash. Statements share A300 pilot group's concerns over possible composite deterioration, uncommanded rudder incidents. Pilots acknowledge agency's hesitancy to ground A300, maintain concerns over continued flight until airworthiness of fleet can be assured; pilots again urge that Non-Destructive Testing (NDT) methods similar to the one that found damage on A300 tail in March be used. Pilots now await NTSB responses to seven other concerns outlined in letter.
On Friday, April 12, in testimony to a congressional appropriations subcommittee, NTSB Chairman Marion Blakey echoed one of the main points outlined in the letter that eight A300 pilots sent to the NTSB and the FAA last month. Taking the NTSB in a new public direction, Blakey urged the subcommittee to allow funding to further investigate composites used in aircraft construction, adding that Flight 587 "poses new issues," including questions as to whether composites in aircraft wear out prematurely (a process known as "fatigue" in metal aircraft structures.) She asked for a significant budget increase in order to hire "additional composite experts."
Blakey also noted that more information was being sought on an "uncommanded rudder" incident involving an Airbus A340 flown by Singapore Airlines. The aircraft experienced "problems with the air speed indicator and recorded dramatic rudder swings that were not commanded by the pilots." The A340's vertical fin and rudder were removed and Non-Destructive testing performed to search for damage. The pilot's letter similarly requested an investigation into over twenty "uncommanded rudder" incidents they had documented on the Airbus A300. Uncommanded rudder events are a serious concern, say the pilots, as the NTSB's Safety Recommendation of February 8, 2002, warns that alternating side loads like those experienced from consecutive full swings of the rudder can cause structural damage to large aircraft. The rudder on AA 587 has been reported to have swung full deflection several times just before the crash. While the NTSB urged the FAA to develop pilot training techniques as part of a recommendation addressing "rudder doublet" (two consecutive, full swings of the rudder), the pilot's letter points out that the aircraft can and has sporadically performed such rudder movements in the past without pilot input. "Although we acknowledge with regret the NTSB's decision to continue to fly the A300 on passenger service without establishing a baseline of structural integrity of the fleet using NDT, we welcome additional investigation into composite issues on commercial airliners and uncommanded rudder events," said First Officer Todd Wissing, one of the pilot's who submitted the letter. The pilots now look forward to NTSB and FAA response on the other seven concerns they raised in the letter, many raised due to the Safety Recommendation by the NTSB on February 8, 2002. They include:
-certification standards of all commercial aircraft's rudder and vertical stabilizers be re-evaluated;
-rudder pedal design issues with certain aircraft, including the A300, the DC-9 and others;
-inspection methods used to find hidden damage on composite applications. (Pilots and many industry experts advocate NDT. Currently, the industry relies on visual inspections or other manual methods.)
-design philosophies of automatic functions such as the Rudder Limiter on certain aircraft be re-evaluated;
--"uncommanded rudder" phenomenon and investigation into the events documented on the A300 in particular;
--pilot training be revised to include instruction on "rudder doublets", the phenomenon outlined in the February announcement, and how pilots are now to apply the flight controls safely;
--redefine the concept of Maneuvering Speed, formerly known as the aircraft design speed below which a pilot could fully deflect flight controls without structural damage, also impacted by the February announcement by the NTSB.
The pilot's views are shared by an increasing number of aviation industry experts and composite engineers, including NASA researchers, USAF research studies, a former NTSB Air Safety chief and many composite pioneers and experts.
Copies of the report can be obtained by e-mail request at: