Kadar je dogodek, sporočen po odstavku (b) ali 21A.129(f)(2) ali 21A.165(f)(2), rezultat pomanjkljivosti v projektih ali izdelavi, bodisi nosilec certifikata tipa, certifikata tipa z omejitvami, dodatnega certifikata tipa, potrdila načrta velikega popravila, dovoljenja ETSO ali kakršnega koli drugega ustreznega potrdila, za katerega se šteje, da je bilo izdano po tej uredbi, bodisi po potrebi proizvajalec, razišče vzrok za pomanjkljivost in agencijo obvesti o rezultatih preiskave in kakršnih koli ukrepih, ki jih izvede ali predlaga za odpravo navedene pomanjkljivosti.
When an occurrence reported under paragraph (b), or under 21A.129(f)(2) or 21A.165(f)(2) results from a deficiency in the design, or a manufacturing deficiency, the holder of the type-certificate, restricted type-certificate, supplemental type-certificate, major repair design approval, ETSO authorisation, or any other relevant approval deemed to have been issued under this Regulation, or the manufacturer as appropriate, shall investigate the reason for the deficiency and report to the Agency the results of its investigation and any action it is taking or proposes to take to correct that deficiency.