EC 225 CHC Helikoper Bergen

A July report by state news agency Yonhap, quoting an official at Seoul’s Defence Acquisition Program Administration (DAPA), said that Airbus Helicopters informed DAPA that the fatal crash of an H225 in Norway was due to a “defective main gearbox”. The report adds that 57% of the Surions in military service will need their gearboxes replaced, and that Airbus will reimburse the South Korean government.

Poncho (Admin) a écrit:Est-ce qu'on doit comprendre que le pb est identifié ? et qu'il n'est pas récurrent ?

Since that AD was issued, Airbus Helicopters (AH) have investigated possible accident contributory factors and determined that the likely cause relates to the rupture of the second stage planet gear, which was found with fatigue and surface degradation. Although the root cause of this failure is still not fully understood, it involved cracking of the planet gear bearing outer race, some spalling and propagation of a crack into the rim of the gear, finally resulting in its rupture.

This Emergency Airworthiness Directive (Emergency AD) 2016-24-51 is being sent to owners and operators of Sikorsky Aircraft Corporation (Sikorsky) Model S-92A helicopters.
Background
This Emergency AD was prompted by a report of an operator losing tail rotor (TR) control while in a hover. A preliminary investigation determined that binding in the TR pitch change shaft (TRPCS) assembly double row angular contact bearing (bearing) resulted in reduced TR control. The investigation also found signs of excessive heat, which is an indicator of a binding bearing. Because binding will result in bearing failure rapidly, we are limiting this Emergency AD to TRPCS assemblies with less than 80 hours time-in-service (TIS). This Emergency AD requires, before further flight, removing from service any TRPCS assembly with less than 5 hours TIS since new or overhaul. For TRPCS assemblies that have 5 or more hours TIS since new or overhaul, this Emergency AD requires a one-time borescope and visual inspections of the TRPCS assembly and bearing to determine the condition of the bearings. The actions in this Emergency AD are intended to detect a binding bearing, prevent loss of TR control, and possible loss of control of the helicopter.
FAA’s Determination
We are issuing this Emergency AD because we evaluated all the relevant information and determined the unsafe condition described previously is likely to exist or develop in other products of the same type design.
Related Service Information
We reviewed Sikorsky Alert Service Bulletin (ASB) 92-64-009, Basic Issue, dated November 2, 2016 (ASB 92-64-009). ASB 92-64-009 describes procedures for inspecting the TRPCS and bearing assemblies for damaged bearings and seals, purged grease with any metallic particles from the bearings, radial play in the bearings, and correct installation of the white Teflon seals, snap rings, and cotter pin.
Emergency AD Requirements
This Emergency AD requires, before further flight, removing TRPCS assemblies with less than 5

At present time, the primary focus of the AIBN investigation is certification aspects of the main gearbox and the robustness of past and present design requirements. This includes the follow-up on safety recommendations issued by the AAIB in connection with the accident involving G-REDL and continuing airworthiness of the gearbox. This work requires good collaboration with the responsible entities, primarily the helicopter manufacturer and the European Aviation Safety Authority (EASA).
The scope and complexity of the investigation means that it is not feasible to estimate a completion date for the final report. The investigation continues with the same high activity. Aviation authorities in Norway and Europe are continually updated about the investigation

For the reason described above, EASA issued AD 2017-0042, requiring a one-time inspection of the MGB oil cooler, and the reporting of all findings to EASA.

Norway says it found vital missing part in Airbus Super Puma investigation -- the epicyclic gear 2nd stage planet gear carrier

— Robert Wall (@R_Wall) 8 mars 2017