According to an airworthiness concern sheet issued on November 18, the FAA is concerned that one of the permitted inspection methods, the Maule fabric test method, is unreliable. The FAA cited “a recent post-accident test of a failed unsealed wing strut by Transport Canada” as the basis for its concern.
Another procedure the FAA has also allowed operators to use to end the inspection requirement has been the installation of specified sealed wing struts. “The FAA is seeking more information regarding the number of remaining unsealed wing lift struts in current use,” the ACS said.
The ACS asks operators of listed aircraft to provide details as to whether they have installed sealed wing struts on their aircraft, whether they did so after corrosion was detected, and if the operators can provide additional information about the “effectiveness of the Maule tester inspection method that would assist the FAA in evaluating further action.”
The FAA also asked operators of aircraft not listed in the ACS’s applicability table who have used the inspection methods to provide any information that might address the concerns.
AOPA encourages operators to respond to the ACS by email or at the mailing address provided in the ACS.