FAA outlines use of lap belts on the 787

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The US FAA has released its guidelines for lap belt airbags for use aboard some seats on Boeing's 787.

In a recently published special condition, the FAA has identified additional conditions of certification that identify the "performance of the system" as well as the lap belt's "integrity against inadvertent activation".

Similar to an airbag in an automotive application, inflatable lap belts integrate the airbag into the lap belt restraint and according to the FAA "the inflatable lap belt has two potential advantages over other means of head impact protection" and "can provide significantly greater protection than would be expected with energy-absorbing pads," as well as "provide essentially equivalent protection for occupants of all stature".

The special condition also opens the door for the use of other lap belt airbags, allowing Boeing to apply the 787's requirements to other models.

"Because a crash requiring use of the inflatable lap belts is a relatively rare event, and because the consequences of an inadvertent activation are potentially quite severe, these latter requirements are probably the more rigorous from a design standpoint," said the FAA.

Because of the significant range of potential users of the lap belt system, the FAA is requiring a means of protection ranging from a two year old child to a male within the 95th percentile of height and weight.

Boeing must demonstrate that the system is "not susceptible to inadvertent deployment as a result of wear and tear, or inertial loads resulting from in-flight or ground manoeuvres including gusts and hard landings, and other operating and environmental conditions such as vibrations or moisture likely to be experienced in service", said FAA.

Post deployment, the system cannot block the emergency lighting system and must function even in the event of the loss of normal aircraft electrical power and following a "transverse separation" of the fuselage.

Further the airbag must withstand lightning and high-intensity irradiated fields that could cause inadvertent activation or disabling of the system.

Prior to each flight, a crew member will be required to "verify the integrity" of the lapbelt activation system or "must be demonstrated to reliably operate between inspection intervals".

Underscoring this point, the FAA considers the loss of the system's deployment function as a "major failure condition".

The FAA's special condition identified only the requirements of the inflatable lapbelt system is "as installed" and noted that the "special conditions are not an installation approval" and "the overall installation approval is a separate finding, and must consider the combined effects of all such systems installed".