NTSB · Safety Recommendation
Safety Recommendation A-21-052
Recommendation
TO EUROPEAN UNION AVIATION SAFETY AGENCY: Identify all currently certificated transport-category airplanes for which system safety assessments for landing gear systems did not consider human error that could lead to cross-wiring of antiskid brake system components, including the wheel speed transducers, and require manufacturers of transport-category airplanes without such assessments to perform the assessments and then implement mitigations to prevent cross-wiring of antiskid brake system components.
Safety Issue and Context
This report discusses the October 17, 2019, accident involving a Saab SA-2000 airplane, operated by Peninsula Aviation Services Inc. d.b.a. PenAir flight 3296, which overran the end of runway 13 at Unalaska Airport, Unalaska, Alaska. The airplane was substantially damaged during the runway overrun; as a result, of the 3 crewmembers and 39 passengers aboard, 1 passenger sustained fatal injuries, and 1 passenger sustained serious injuries. Eight passengers sustained minor injuries, most of which occurred during the evacuation.
Safety issues identified in this report include the potential for cross-wiring of airplane antiskid brake systems; insufficient Federal Aviation Administration (FAA) guidance to identify safety risks for air carriers experiencing significant organizational changes, including bankruptcy, acquisition, and merger; lack of FAA consideration of runway safety area dimensions during the process of authorizing an air carrier to operate its aircraft at a specific Title 14 Code of Federal Regulations Part 139 certificated airport, and the benefits of safety management systems for design, manufacturing, and maintenance organizations.
As a result of this investigation, the National Transportation Safety Board makes six new safety recommendations to the FAA, three new safety recommendations to the European Union Aviation Safety Agency, and one new recommendation to the Saab Group.
Response History
January 28, 2025 · NTSB Correspondence · European Aviation Safety Agency
You previously informed us that you had distributed Continuing Airworthiness Review Item (CASI) 25-10, which asked Airbus, Leonardo, Dassault, Fokker, and Saab to assess their current antiskid brake system components, including the wheel speed transducers, for potential electrical misconnections and the effect of any potential cross-wiring. The CASI also directed manufacturers to ensure that their SSAs include all identified failure conditions and, if the failure condition is critical, mitigations to prevent or minimize the effect of cross-wiring.
We note that, although you are still reviewing manufacturers’ responses to the CASI, the responses you have reviewed indicate that most product designs incorporate hardware or procedural solutions that adequately protect against potential electrical misconnections and the effect of any potential cross-wiring. We also note that the CASI has resulted in some manufacturers updating their aircraft maintenance manuals.
Although we continue to believe your work to distribute the CASI and review manufacturers’ responses are responsive, my staff would like to meet with your staff to discuss the following items:
• How many total product designs were reviewed and how many of those did not consider human error in their SSA for the landing gear system? • For those product designs that have since performed the SSA, as recommended, we would like to review the portion of the SSA related to the mitigations that were implemented. • For the product designs that did not consider human error in their initial SSA and have not performed another SSA, as recommended, we would like to review the documentation showing how the manufacturer determined that any mitigations they have implemented adequately protect against potential electrical misconnections and the effect of any potential cross-wiring.
My staff has reached out to your staff to schedule a meeting. Pending our review of this additional information and completion of the recommended actions, Safety Recommendation A-21-52 remains classified OPEN-- ACCEPTABLE RESPONSE.
March 22, 2024 · Recipient Response · European Aviation Safety Agency
-From Ralf Erckmann, Head of Safety Intelligence & Performance Department: Since the issuance of the Continued Airworthiness Review Item (CARI) 25-10 (March 2022), inquiring if their landing gear systems / architecture is robust to potential cross-wiring of antiskid brake system components, and how their system safety assessments considered those failure condition(s), and the potential need for mitigation, the European Union Aviation Safety Agency (EASA) received feedback from the Large Aeroplane EU Type Certificate holders.