As airlines revamp their cabins with new seating concepts and cutting-edge inflight entertainment (IFE) systems, suppliers are having to adapt to precertification testing regimes that are evolving with equal complexity.
“Seats are still the main focus for testing and certification, because they are so integral to passenger safety,” says Michael Planey, president of HMPlaney Consultants in Alexandria, Virginia. “As more components are incorporated into seating, such as IFE monitors, motors for seat recline, and movable headrests, testing and certification becomes a more complex effort.”
Airline seats must be able to restrain passengers and resist deformation up to 16 times the force of gravity (16g) in the event of a crash. Compliance is determined through dynamic testing and evaluation for injury protection, required by the FAA since 1988 for all newly developed transport aircraft. The previous standard was 9g, based on static testing with no injury criteria. On Oct. 27, 2005, the FAA amended the regulations, mandating that all transport category aircraft, operating under Part 121, certificated after Jan. 1, 1958, and manufactured on or after Oct. 27, 2009, be equipped with seats meeting the 16g standard. As the trend toward lighter-weight seats gains traction, new testing issues are emerging.
“The challenge for seating manufacturers is to arrive at the proper balance between something that is made out of lighter-weight yet durable materials, and compliance with the 16g test,” explains Tom Knott, an FAA Designated Engineering Representative. “This is driving a considerable amount of testing activity today.”
Gary Weissel, managing officer of Tronos Aviation Consulting in Atlanta, says that when seats go through the 16g testing, some design changes will invariably result. “This will often impact the test’s repeatability results,” he says. “The lighter the seats are, the more challenging it is to certify them under the 16g repetitive testing requirements.”
Weissel adds that although testing and certification are the seat manufacturers’ responsibility, there may be some risk for the buyer. “Seats are highly customized. But even if an airline buys an off-the-shelf product, some additional testing may be required for certification because different materials or parts may be specified,” he notes. “That could require additional dynamic, burn and static testing prior to the seats’ delivery to the customer, who could end up paying a nonrecurrent engineering charge. This is not uncommon.”
Those types of issues could move testing toward computer analysis—still in the research and discussion stage—and away from today’s labor- and equipment-intensive regimes, says Knott.
“Computer analysis is evolving with improved software products that analyze the data from the seating OEMs,” he says. “Although the regulatory authorities are open to it, we are about five years away from approval of computer-based 16g testing.”
Jacques Debouchaud, research and innovation manager for cabin interiors for Stelia Aerospace in Rochefort, France, confirms that seat testing has become increasingly focused on flammability and crash dynamics. To address that, Stelia Aerospace is testing airbag-equipped seats. “When you add airbags, crash testing moves toward the automotive world, which is in compliance with such human criteria as prevention of neck and leg injuries,” he says. “This is one example in which passenger-safety improvements will lead to evolving testing standards.”
Debouchaud adds that attention is also being paid to IFE. “The video screens, mounted in the seatbacks facing the passenger, are getting larger, which makes it harder to avoid contact during a crash. At Stelia Aerospace, we have designed a more absorbent screen installation to mitigate the potential for head injuries. That has undergone a proprietary testing program.”
There are multiple safety objectives for video monitor testing, according to George Smallhorn, president of Inflight Canada, a Montreal-based design, integration and maintenance provider of commercial aircraft cabin systems. One objective is “delethalization,” to demonstrate that after a passenger’s first impact with an installed object, lethal injuries will not result. “As part of the head injury criteria testing, you also need to demonstrate that the video screen will not shatter so that if the passenger’s head impacts it a second time, it will not be cut,” he says. “The goal is to avoid a wound injury.” Smallhorn adds that this testing parameter applies only if the video monitor is within 35 in. of the seat reference point.
Moving away from embedded audio/video on-demand (AVOD) to wireless IFE has brought the susceptibility of the aircraft’s systems to wireless signals into the testing regime, says Smallhorn. Known as transmitting personal electronic device (TPED) testing, its purpose is to determine how the aircraft will or will not react to wireless signals emitting from any personal electronic device (PED).
To carry out a TPED test, which takes about two days, special test gear is installed in the passenger cabin of a representative aircraft that has been removed from revenue service and parked away from occupied buildings. The test equipment, Smallhorn explains, can create wireless-type transmissions on various frequencies and signal strengths to saturate the aircraft with signals typical of those emanating from a multitude of PEDs, and at about four times the power. “We then operate all of the aircraft’s systems, with and without the engines in operation, looking for anomalies that may be induced by these wireless signals.”
If no impact has been detected, the wireless system is installed. A certification testing process follows, to determine if the system’s operation will affect the aircraft in any way—as is done for the embedded AVOD systems. “This testing is accomplished without saturating the cabin with PED transmissions—involving only the transmissions of the wireless system itself. The wireless system certification includes ground tests, followed by a flight test,” says Smallhorn.
He adds that among the major differences between wireless and embedded systems is that once a supplemental type certificate (STC) for a wireless system is issued, the operator cannot use it until it applies for, and receives, an exemption from the responsible airworthiness authority.
Testing is also evolving with respect to cabin component flammability and toxicity. The highest level of main cabin flammability requirements applies to airplanes with 20 or more seats, notes Lori Louthan, director for mass transportation for Saudi Arabia Basic Industries Corp. (Sabic), a supplier of plastics for aircraft applications. The requirements, she says, pertain to most large main cabin parts and surfaces that are exposed during taxi, takeoff and landing, and need to meet heat release, optical smoke density and vertical Bunsen burner testing.
“The regulations cover interior ceiling and wall panels, partitions, galley structures, large cabinets, and stowage compartments,” says Louthan. “Seating is subject to special conditions. Large, exposed, nonmetallic seating surfaces could be required to meet the same heat release and smoke tests as those for main cabin components.”
Asked if major changes are taking place regarding flammability testing, Louthan cites the implementation of “seat special conditions,” which require adding heat release and optical smoke density testing to existing Bunsen burner testing for some large, nonmetallic, nontraditional, exposed surfaces of seats in aircraft carrying 20 or more passengers.
Other changes, she notes, are being considered by both the FAA and the European Aviation Safety Agency, including: elimination of the optical smoke density test—a more stringent test for some hidden space applications (such as ducting), simplification of the seat special conditions that may include more seat parts needing heat release, and elimination of the heat release test for parts of walls and monuments that are within a certain distance of the floor.