NTSB · Safety Recommendation
Safety Recommendation A-21-055
Recommendation
TO THE SAAB GROUP: Redesign the wheel speed transducer wire harnesses for the Saab 2000 airplane to prevent the harnesses from being installed incorrectly during maintenance and overhaul.
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
November 14, 2023 · NTSB Correspondence · Saab Aircraft of America, Inc.
The National Transportation Safety Board (NTSB) has reviewed the Federal Aviation Administration's (FAA) notice of proposed rulemaking titled, “Airworthiness Directives; Saab AB, Support and Services (Formerly Known as Saab AB, Saab Aeronautics) Airplanes,” which was published at 88 Federal Register 69105 on October 5, 2023. The notice proposes a new airworthiness directive (AD) applicable to all Saab AB, Support and Services Model Saab 2000 airplanes.
This proposed AD was prompted by a fatal accident involving a Saab 2000 airplane that occurred on October 17, 2019, in Unalaska, Alaska. The NTSB determined the probable cause to be, in part, “the landing gear manufacturer’s incorrect wiring of the wheel speed transducer harnesses on the left main landing gear during overhaul. The incorrect wiring caused the antiskid system not to function as intended, resulting in the failure of the left outboard tire and a significant loss of the airplane’s braking ability, which led to the runway overrun.”
As a result, the NTSB issued Safety Recommendation A-21-55 asking the Saab Group to redesign the wheel speed transducer wire harness for the Saab 2000 airplane to prevent the harness from being installed incorrectly during maintenance and overhaul.
On May 15, 2023, Saab issued Service Bulletin (SB) 2000-32-084 Revision 1, which includes instructions for installing color markings on the harnesses and the wheel axles to ensure proper installation and connection of the anti-skid harnesses. The proposed AD would require the modifications described in Saab’s SB. The FAA is proposing this AD to address this unsafe condition, which, if not detected and corrected, could lead to wrong inputs to the anti-skid function, whenever activated, with consequent reduced braking capability, possibly resulting in damage to the airplane.
The NTSB believes that this proposed AD will improve safety by reducing the likelihood that this type of accident is repeated; therefore, we agree with its intent and have no technical objections to the proposed design improvements.
Thank you for the opportunity to comment on this NPRM.
May 24, 2023 · NTSB Correspondence · Saab Aircraft of America, Inc.
We note that you are reviewing Heroux Devtek’s draft Service Bulletin AIR83132-32-03, which you received in February. The draft includes a modification that will introduce color code markings on the landing gear axle and the antiskid harness end connectors. We look forward to reviewing the published modification. Pending our receipt and review of this information, Safety Recommendation A-21-55 remains classified OPEN-- ACCEPTABLE RESPONSE.