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Safety Recommendation Details

Safety Recommendation A-10-170
Details
Synopsis: On August 9, 2010, about 1442 Alaska daylight time, a single engine, turbine-powered, amphibious float-equipped de Havilland DHC-3T airplane, N455A, impacted mountainous tree-covered terrain about 10 miles northeast of Aleknagik, Alaska. Of the nine people aboard, the airline transport pilot and four passengers died at the scene, and four passengers sustained serious injuries. The airplane sustained substantial damage. The flight was operated by General Communication, Incorporated (GCI), Anchorage, Alaska, under the provisions of 14 Code of Federal Regulations (CFR) Part 91. The flight originated at a GCI-owned remote fishing lodge on the southwest shoreline of Lake Nerka about 1427 and was en route to a remote sport fishing camp on the banks of the Nushagak River, about 52 miles southeast of the GCI lodge. At the time of the accident, marginal visual meteorological conditions were reported at the Dillingham Airport, in Dillingham, Alaska, about 18 miles south of the accident site; however, the weather conditions at the accident site at that time are not known. No flight plan was filed.
Recommendation: TO THE FEDERAL AVIATION ADMINISTRATION: Determine if the emergency locator transmitter (ELT) mounting requirements and retention tests specified by Technical Standard Order (TSO) C91a and TSO C126 are adequate to assess retention capabilities in ELT designs. Based on the results of this determination, revise, as necessary, TSO requirements to ensure proper retention of ELTs during airplane accidents.
Original recommendation transmittal letter: PDF
Overall Status: Closed - Acceptable Action
Mode: Aviation
Location: Aleknagik, AK, United States
Is Reiterated: No
Is Hazmat: No
Is NPRM: No
Accident #: ANC10MA068
Accident Reports: Collision into Mountainous Terrain, GCI Communication Corp. de Havilland DHC-3T, N455A
Report #: AAR-11-03
Accident Date: 8/9/2010
Issue Date: 1/5/2011
Date Closed: 3/22/2013
Addressee(s) and Addressee Status: FAA (Closed - Acceptable Action)
Keyword(s): Emergency Locator Transmitter

Safety Recommendation History
From: NTSB
To: FAA
Date: 3/22/2013
Response: The NTSB is aware that, on November 26, 2012, the FAA issued TSO-126b, which precludes TSO authorizations of new ELT designs that use hook and loop fasteners as a means of securing an ELT in its mounting tray. We believe the contents of TSO-126b and the FAA’s scheduled withdrawal of TSO Authorizations issued for the manufacture of automatic fixed and portable ELTs under TSO C91a, TSO-C126, and TSO-C126a will prevent the manufacture after June 30, 2014, of new ELTs with unacceptable attachment methods. However, we remain concerned that the FAA is not taking similar action to address the thousands of ELTs with hook and loop fasteners that are already installed in airplanes or are available for purchase. Because there is no requirement for owners and operators to retrofit currently installed devices with improved attachment methods, hook and loop ELT fasteners will continue to be in use for the foreseeable future, and the problem of unintentional detachment during accidents will likely persist. Accordingly, we encourage the FAA to issue a requirement to retrofit existing ELTs that use hook and loop fasteners with an acceptable alternative attachment method or to replace the ELT with one that incorporates an acceptable means of attachment. However, because the FAA’s actions address the intent of Safety Recommendation A-10-170, the recommendation is classified CLOSED—ACCEPTABLE ACTION. Thank you for your commitment to improving aviation safety.

From: FAA
To: NTSB
Date: 11/8/2012
Response: -From Michael P. Huerta, Acting Administrator: The Federal Aviation Administration (FAA) evaluated the mounting requirements and retention tests specified in TSO-C91a, TSO-CI26, and TSO-CI26a. These TSOs specifically address ELT mounting and require the mounting design to meet certain specifications. However, they do not require or preclude any specific type of retention mechanism. Based upon its evaluation, the FAA determined that the standards contained in these TSOs do not adequately address the use of hook and loop fasteners. While these types of fasteners can meet the TSO requirements for retention forces in laboratory conditions, accident investigations have found these fasteners are not reliable in service. To resolve this issue the FAA is taking the following actions: • As a preliminary step, the FAA issued Special Airworthiness Information Bulletin (SAIB) HQ-12-32, Hook and Loop Style Fasteners as a Mounting Mechanism for Emergency Locator Transmitters, on May 23, 2012. This SAIB brings immediate attention to this issue and outlines actions ELT manufacturers can take to improve their installation and maintenance instructions to mitigate the concerns with hook and loop EL T retention. The FAA plans to work with manufacturers that already hold TSO authorizations for TSO-C91 a, TSO-C 126, and TSO-CI26a. • TSO-C126a is being revised to prohibit the use of hook and loop fasteners, commonly referred to as Velcro®, as an acceptable means of attachment to the aircraft. The TSO-C 1263 revision will impact newly designed ELTs. On July 13, 2012, we published Proposed TSO-CI26b, 406 MHz Emergency Locator Transmitters and Notice of Intent to Withdraw TSO Authorizations (TSOA) for TSO-C91a, Emergency Locator Transmitter Equipment, and TSO-CI26/ C126a, 406 MHz Emergency Locator Transmitters (77 FR 4 1475). The notice announces the FAA's intent to withdraw TSO authorizations issued for the manufacture of automatic fixed and automatic portable ELTs under TSO-C91 a, TSO-CI26, and TSO-C 126a that incorporate hook and loop fasteners in their design unless the design is revised to replace the hook and loop fasteners with an acceptable alternative and the installation and maintenance manuals are updated. TSO-C91a was previously cancelled for unrelated reasons. The comment period closed on September II, 2012. The FAA expects to issue the revision to TSO-C 126a this month. I will keep the Board informed of the FAA's progress on this safety recommendation and provide an update by April 30, 2013.

From: NTSB
To: FAA
Date: 9/6/2012
Response: Notation 8435: The National Transportation Safety Board (NTSB) has reviewed the Federal Aviation Administration’s (FAA) notice of availability and request for public comment, titled “Proposed Technical Standard Order (TSO)-C126b, 406 MHz Emergency Locator Transmitters (ELT) and Notice of Intent to Withdraw TSO Authorizations (TSOA) for TSO-C91a, Emergency Locator Transmitter (ELT) Equipment, and TSO-C126/C126a, 406 MHz Emergency Locator Transmitters (ELT),” which was published at 77 Federal Register 41473 on July 13, 2012. This notice announces the availability of proposed TSO-C126b, which, if adopted, would preclude TSOAs of new ELT designs that use hook and loop fasteners as a means of securing an ELT in its mounting tray. The notice also announces the FAA’s intent to withdraw TSOAs issued for the manufacture of automatic fixed and automatic portable ELTs under TSO C91a, TSO-C126, and TSO-C126a, which incorporate hook and loop fasteners into their design, by June 30, 2014, unless the design is revised to replace the hook and loop fastener with an alternative acceptable to the FAA. The FAA also proposes to withdraw TSOAs issued for these ELTs one year earlier, on June 30, 2013, unless installation and maintenance instructions are revised to include detailed instructions for properly securing the ELT during installation and reinstallation, detailed instructions for inspecting hook and loop fasteners, and a replacement interval for in-service hook and loop fasteners. The FAA is not proposing requiring actions on previously installed ELTs. The FAA is taking these actions based on its determination that hook and loop fasteners are not an acceptable means of compliance to meet the mounting and retention requirements of current TSOs for ELTs. The FAA acknowledges that TSO-C91a, TSO-C126, and TSO-C126a specifically address ELT mounting and require the mounting design to meet certain specifications; however, they do not require or preclude any specific type of retention mechanism. While the hook and loop fasteners can meet the TSO retention requirements under laboratory conditions (and TSOAs have been granted on this basis), recent accident data indicate that hook and loop fasteners are not reliable in service and may fail to retain an ELT during an accident. In its notice, the FAA cites the NTSB’s investigation of an accident in which the ELT came loose from its hook and loop fastener during impact. On August 9, 2010, a de Havilland DHC-3T, N455A, sustained substantial damage when it impacted mountainous tree-covered terrain about 10 miles northeast of Aleknagik, Alaska. The airplane was equipped with a 406 MHz ELT, which separated from its mounting tray during impact with sufficient force to disconnect the antenna from the ELT unit. Although the ELT transmitted a distress signal, the signal was not detected because the antenna was disconnected; thus, search and rescue activities were delayed for several hours. The ELT had been attached to its mounting tray by a webbed strap with a hook and loop fastener and had successfully passed all retention tests required by TSO-C126a. As a result of this accident investigation, on January 5, 2011, the NTSB issued Safety Recommendation A-10-170, which asked the FAA to do the following: Determine if the emergency locator transmitter (ELT) mounting requirements and retention tests specified by Technical Standard Order (TSO) C91a and TSO C126 are adequate to assess retention capabilities in ELT designs. Based on the results of this determination, revise, as necessary, TSO requirements to ensure proper retention of ELTs during airplane accidents. The NTSB generally supports proposed TSO-C126b and the intent to withdraw the TSOAs for newly manufactured devices using hook and loop fasteners. These actions will prevent the manufacture of new ELTs with unacceptable attachment methods after June 30, 2014. However, the NTSB is concerned that the FAA is not taking action to address the thousands of ELTs with hook and loop fasteners that are already installed in airplanes or are available for purchase. Because there is no requirement for owners and operators to retrofit currently installed devices with improved attachment methods, hook and loop ELT fasteners will continue to be in use for the foreseeable future, and the problem of unintentional detachment during accidents will likely persist. The NTSB believes the FAA should consider a requirement to retrofit existing ELTs that use hook and loop fasteners with an acceptable alternative attachment method or to replace the ELT with one that incorporates an acceptable means of attachment. The NTSB appreciates the opportunity to comment.

From: NTSB
To: FAA
Date: 5/1/2012
Response: The FAA indicated that, although it has determined the shock requirements and tests specified in TSO-C91a and TSO-C126, in general, to be appropriate, it intends to revise the TSOs to prohibit the use of non-rigid ELT mounting designs. We believe that the FAA’s plan to revise the TSOs to prohibit the use of such designs will satisfy this recommendation. In the meantime, pending our receipt and review of the revised TSOs, Safety Recommendation A-10-170 remains classified OPEN—ACCEPTABLE RESPONSE.

From: FAA
To: NTSB
Date: 1/4/2012
Response: -From Michael P. Huerta, Acting Administrator: The Federal Aviation Administration (FAA) reviewed the mounting requirements and retention tests in Technical Standard Order (TSO) C91a and TSO-C126. The FAA found, in general, the shock requirements and tests are appropriate. However, the RTCAlDO-183, Minimum Operational Performance Standards for Emergency Locator Transmitters-Automatic Fixed-ELT (AF), Automatic Portable-ELT (AP), Automatic Deployablc-ELT (AD), Survival-ELT (S) Operating on 121.5 and 243.0 Megahertz, and DO-240A, Minimum Operational Performance Standards for 406 MHz Emergency Locator Transmitters (ELT), minimum performance standards for TSO-C91a and TSO C126a, respectively, do not address the use of non-rigid ELT mounting designs. For this reason, we are working to revise the T805 to prohibit the use of non-rigid ELT mounting designs. I will keep the Board informed of the FAA's progress on this safety recommendation and provide an updated response by December 30, 2012.

From: NTSB
To: FAA
Date: 5/25/2011
Response: Based on (1) the FAA’s work to determine whether the ELT in the Aleknagik accident met the retention standards specified in TSO-C126 and (2) the FAA’s review of TSO C91a and TSO-C126a to determine whether revisions are necessary to address ELT retention, the NTSB classified Safety Recommendation A-10-170 OPEN – ACCEPTABLE RESPONSE, pending completion of the recommended action.

From: FAA
To: NTSB
Date: 3/21/2011
Response: CC# 201100118: - From J. Randolph Babbitt, Administrator: We are working with the Seattle Aircraft Certification Office and the ELT manufacturer to determine whether the ELT meets the standards ofTSO-C126. Additionally, the FAA will review TSO-C91a and TSO-C126a to determine whether revisions are necessary to address the intent of this recommendation. I will keep the Board informed of the FAA's progress on this safety recommendation and will provide an updated response by August 1, 2011.