EASB - Eurocopter

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1. PLANNING INFORMATION 1.A. EFFECTIVITY 1.A.1. Helicopters/installed equipment Helicopters equipped with a Main Gearbox (MGB) fitted with a bevel gear with part number 332A32-5101-00, 332A32-5101-05, 332A32-5101-10 or 332A32-5101-15, Regardless of the overflown areas. 1.A.2. Non-installed equipment Not applicable. 1.B. ASSOCIATED REQUIREMENTS Not applicable. 1.C. REASON NOTE 1 Refer to the Log Cards to identify the actual configuration of the helicopter. <strong>EASB</strong> Revision 0: Following the ditching of an EC225 helicopter in the North Sea, failure of the bevel gear of the MGB was found during the investigations carried out under the authority of the AAIB with the co-operation of BEA, EASA and EUROCOPTER. The analyses launched in the EUROCOPTER Design Office and Laboratory on the part showed that the failure was due the growth of a fatigue crack in the vertical shaft part. Failure of this part leads to the total loss of MGB lubrication pressure without affecting the power transmission to the Main Rotor. EUROCOPTER reminded through SIN No. 2450-S-00 that compliance with the emergency procedures defined in the Flight Manual ensured safety. The download of the vibration data delivered by the Vibration Health Monitoring system (VHM) showed a rising trend in certain indicators during the last few flights. The technical analysis performed by EUROCOPTER has shown the relationship between this rising trend of the vibrations and the growth of the fatigue crack. In order to minimize the risk of having to perform an emergency ditching, in accordance with the Flight Manual procedures, the EASA has issued Airworthiness Directive No. 2012-0107 for the EC225 fleet. This Airworthiness Directive limits offshore flights to certain operational conditions unless mandatory analysis of the VHM indicators is performed every 4 flying hours. The analyses performed since the incident on the bevel gear revealed a number of parts that may be affected by the phenomenon causing the crack and that these parts could be installed on any SUPER PUMA family helicopter type. Revision 0 2012-06-27 Page 2/15 Revision 2 2012-11-21 This document is available on the internet: www.eurocopter.com/techpub
<strong>EASB</strong> EUROCOPTER is currently working on the definition of retrofit measures for the parts in service, which will enable to cancel the limitations defined in this ALERT SERVICE BULLETIN. As of now, the parts which are currently being produced are reworked and have a serial number greater than or equal to M5000. Pending the retrofit measures and in order to minimize the risk of being obliged to perform an emergency ditching in case of a rough sea, EUROCOPTER renders compliance with the limitations of offshore flights defined in this ALERT SERVICE BULLETIN, mandatory. Revision 1: Following the ditching of an EC225 helicopter in the North Sea on October 22, 2012, - the inquiry is currently being conducted under AAIB-supervision with the cooperation of the BEA, the EASA and EUROCOPTER, - the failure of the MGB bevel gear has been identified. The serial number (S/N) of this part was not concerned by the Revision 0 of the present ALERT SERVICE BULLETIN Pending the analyses whose goal was to identify the reason for the failure of this component, EUROCOPTER made compliance with the limitations for offshore flights, defined in this ALERT SERVICE BULLETIN, mandatory for all serial numbers (S/Nos.) of bevel gear vertical shafts including those with serial numbers equal to or above M5000. According to the results of the investigations which will be conducted on the MGB bevel gear which was involved in the incident that occurred on October 22, 2012, the components with serial numbers equal to or above M5000 may no longer be concerned by the instructions of this ALERT SERVICE BULLETIN. EUROCOPTER will keep you informed of the progress of the investigations. Revision 1 of this ALERT SERVICE BULLETIN affected compliance with Revision 0. Revision 2: EUROCOPTER currently adopts all means available to identify the root cause of the failure of the bevel gear. The crack in the second case is not initiated from the hole of the welded area, introducing new assumptions for the failure cause. Various tests in flight, on the ground and in the Laboratory have been launched to confirm the assumptions made on the complete failure scenario. Pending the results and in order to increase the flight safety of the Super Puma fleet, EUROCOPTER introduces the following complementary measures: - Modification of the Flight Manual procedure, for all EC225 and EC725 helicopters, in case of bevel gear failure. In case of bevel gear failure, the top part of the bevel gear continues transmitting the power to the main rotor, but all the meshing loads are transferred to the upper bearing. Following the investigations conducted on the 2 bevel gears, it was found that this bearing and the meshing part of the bevel gear were in good condition after having operated during almost 10 minutes after failure. Supported by the calculations performed, EUROCOPTER is therefore confident that in similar cases, the 30 flying minutes permitted by the Flight Manual after activation of the emergency lubrication can be performed without worsening of the scenario. Nevertheless, EUROCOPTER will launch tests to demonstrate the latter. Pending the results of these tests, a new procedure requiring immediate landing is defined for this specific case. - Specifically for EC225 / EC725 performing operations which do not enable an emergency landing on the ground within 10 minutes at Vy: - Reduction by 15% of the Maximum Continuous Power (MCP) during level flights, in order to: o significantly increase the propagation time of a crack o increase the safety coefficients in order to ensure safety by analyzing the VHM data every 3 flying hours. - Reduction to 0.20 “g rms” max. of the red threshold of the M’ARMS MOD-45 indicator and deletion of the amber threshold. Revision 0 2012-06-27 Page 3/15 Revision 2 2012-11-21 This document is available on the internet: www.eurocopter.com/techpub
Page 1: EASB EMERGENCY ALERT SERVICE BULLET
Page 5 and 6: 1.E. COMPLIANCE 1.E.1. Compliance a
Page 7 and 8: EASB 2) If you need to perform a fl
Page 9 and 10: 1.F. APPROVAL Approval of modificat
Page 11 and 12: 2. MATERIAL INFORMATION 2.A. MATERI
Page 13 and 14: LES OPERATIONS NE PERMETTANT PAS UN
Page 15: APPENDIX 2 2 MAIN GEARBOX LUBRICATI

EASB - Eurocopter

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