BOEING HAS requested a temporary exemption from US Federal Aviation Administration head-injury criteria (HIC) certification rules for some economy-class seats on the 777 until May 1996.
The company, like others, has been struggling for some four years to find ways of meeting the HIC requirements and has experimented with a range of potential solutions (Flight International, 19-25 August, 1992).
Manufacturers of smaller affected aircraft, notably British Aerospace, Saab and Bombardier, have found technical solutions, but the issue is more difficult for the only large airliner affected - the 777.
"Boeing filed with the FAA at the end of January for a time-limited extension when it became clear that some of the seats would not be fully compliant with the new rules," says the company.
The rules call for newly certificated air-transport types to have cabins configured to allow 16g-capable seats to be installed to meet the HIC rules, even when immediately behind a vertical surface such as a bulkhead or galley.
The FAA says: "The closing date for comments is 9 March, 1995, and we shall be making a decision after that." Boeing says that some, but not all, of the required seat improvements have been made already.
"The seats on the 777 are safer than anything in the current fleet, despite not being fully compliant," says the company, which declines to specify the improvements yet to be made.
The temporary exemption - until 1 April, 1996 - will allow further improvements to seats in the first row of the economy section in most configurations.
Up to eight rows in the front of the section could be included in the exemption. "This number differs according to each airline's layout," says Boeing, which expects to retrofit "less than 30" 777s which will have been delivered by the time the exemption runs out.
First- and business-class seating, with larger pitch between each seat and 777 cabin bulkheads, will comply with the new ruling.
Source: Flight International
