The U.S. NTSB notes that there have been several survivable accidents in the last 3 years in which overhead bins and passenger service units (PSU) on Boeing 737 airplanes became separated from their attachments during the accident sequences. This suggests that current crashworthiness test requirements do not provide an adequate basis on which to evaluate how these items will withstand impact forces during survivable accidents.
In reviewing the accidents, the NTSB concluded that the separation of PSU’s and overhead bins likely increased the number of reported occupant injuries, particularly injuries to the head and face. These findings prompted the NTSB to issue six safety recommendations to the Federal Aviation Administration:
- Modify the design and test requirements for the attachment points of passenger service units to account for the higher localized loading that results from the relative motion of the attachment structure. (A-12-1)
- Require that the installation design for overhead bins and passenger service units (PSU) manufactured by Boeing and installed in Boeing 737NG series airplanes be modified so that the PSUs remain attached to the bins or are captured in a safe manner during survivable accidents. (A-12-2)
- Review the designs of manufacturers other than Boeing for overhead bins and passenger service units (PSU) to identify designs with deficiencies similar to those identified in Boeing’s design, and require those manufacturers, as necessary, to eliminate the potential for PSUs to separate from their attachments during survivable accidents. (A-12-3)
- Develop test criteria and performance measures for negative-g strap assemblies to better evaluate their real-world loading capability during accident sequences. (A-12-4)
- Once test criteria and performance measures are established as recommended in Safety Recommendation A-12-4, amend 14 Code of Federal Regulations Part 25, as appropriate, to include the newly developed test criteria and performance measures for negative-g strap assemblies. (A-12-5)
- Require that negative-g strap attachment brackets manufactured by Ipeco be retrofitted with stronger brackets. (A-12-6)