scope:

Reason:

Prompted by reports of finding cracks in MR lower hubs installed on MD900 helicopters, MDHI published Notices to inform all affected owners and operators, requesting that special attention be given to the MR (lower) hub assembly during daily pre-flight and scheduled 100 hour inspections, to detect any cracks or other anomalies and to request that any discrepancies are reported to MDHI. The Federal Aviation Administration (FAA), the State of Design authority for the affected MD900 helicopters, issued AD 2010-18-52 to require a one-time inspection of all Part Number (P/N) 900R2101008-103, -105 and -107 MR lower hubs for cracks and replacement of any cracked hubs with airworthy units. FAA AD 2010-18-52 dated 16 November 2010 was adopted by EASA.

Since that AD was issued, MDHI determined that one component manufacturer had incorrectly inserted flanged bushings into the lower hub bore that resulted in local corrosion, leading to fatigue cracking. Examination of lower hubs from the other manufacturer showed correct bushing installation. Prompted by these findings, MDHI issued Service Bulletin (SB) SB900-117 to provide instructions for repetitive Eddy Current (EC) inspections of a specific batch of P/N 900R2101008-107 MR lower hubs, having serial numbers (s/n) starting with 5009, and eventual removal from service, within three years, of the affected MR lower hubs.

After issuance of MDHI SB900-117, the FAA issued AD 2011-14-05 (superseding AD 2010-18-52) which limits the applicability to the specific batch of MR lower hubs, retains the visual inspection but at a different compliance time, requires a one-time EC inspection, and retains the requirement to replace a cracked lower hub with an airworthy lower hub. After a full review of the available information, EASA adopted FAA AD 2011-14-05 for the affected helicopters registered in Europe.

However, EASA noticed that FAA AD 2011-14-05 did not require the repetitive inspections as detailed in MDHI SB900-117, nor did it require removal from service of all affected MR lower hubs. For the reasons described above, pending the issuance of an FAA AD, EASA issued AD 2011-0200 to require repetitive EC inspections of the affected MR lower hubs, replacement of cracked parts before next flight, and replacement of all affected MR lower hubs within three years.

Since EASA AD 2011-0200 was issued, the FAA published AD 2012-21-01 (superseding FAA AD 2011-14-05) which will become effective on 27 November 2012. This new FAA AD combines the requirements of FAA AD 2011-14-05 and EASA AD 2011-0200.

For the reasons described above, EASA has adopted FAA AD 2012-21-01 and EASA AD 2011-0200 is hereby cancelled accordingly.