EASA recently held a Koito briefing session in Cologne to help answer some of the myriad questions being asked by airlines. Koito seats are subject to both an EASA proposed AD and an FAA NPRM after the Japanese manufacturer falsified test data on 150,000 seats in the world fleet.
The ‘question and answer summary’ document published by EASA following the 14 October briefing is truly a page turner, and frankly the whole darn thing should be highlighted.
But I’d like to point out one of the key questions, number 19, which addresses why EASA wants all Koito seats removed within 10 years, even the seats that pass the tests in its proposed AD.I’ve italicized – and bolded – some of the most salient bits.
19. Why does EASA feel the need to put a maximum 10 year limit on continued service of seats even if they successfully passed testing for the other compliance time limits set in the AD?
“EASA has been unable to find a way to accept that seats which do not comply with appreciable parts of the applicable requirements remain in service indefinitely. Part 21, AMC 21A.3B(b) Unsafe Condition, paragraph (c), is part of the definition of an “Unsafe Condition”, and reads; “(c) Design features intended to minimise the effects of survivable accidents are not performing their intended function.”
The ten year limit in the AD applies to seats which have shown compliance to only an abbreviated (relative to the full set of applicable requirements) test programme. These seats will thus still be lacking proof of compliance to some requirements.
After consideration of the requirements in question, EASA believes that the associated reduced level of safety still constitutes an Unsafe Condition which must be handled by setting an upper limit on continued service of seats.
The figure of ten years was determined by taking an extreme optimistic view on the same accident data as used above. Assuming only one accident of those studied constituted a situation where occupant protection performance right up to the limit of that provided by the certification basis was essential, the accident rate to consider rate drops to 6.8E-9. Again, assuming a Catastrophic failure mode (multiple fatalities) and an aircraft life of 100,000 FH, this generates a compliance time of; Tc=100,000×0.025E-7/6.8E-9 = 36765 FH So, bearing in mind that this figure is the result of assuming only one accident was sufficiently severe to constitute a need for the full protection afforded by the certification basis, the choice of ten years is also to be seen as a generous allowance.”
EASA says it is being “generous” with a 10-year allowance. If EASA is generous, how should one characterize the FAA’s NPRM, which does not include a requirement that seats ultimately be permanently removed?
When an operator asks – in question 11 – why the NPRM didn’t include HIC (or any of the other compliance criteria not included), EASA says:
“This is one area where the EASA and FAA ADs differ. The EASA AD does require compliance to be shown to all compliance criteria after a period of maximum 10 years. This is because of regulatory issues which place difference onuses on EASA and the FAA for the removal of an Unsafe Condition.”
(Photo above from gordontarpley’s Flickr photo stream)