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H225 LN-OJF 

H225 LN-OJF 

Accident investigation status

A message from Gilles Bruniaux, Head of Aviation Safety

Gilles Bruniaux, Head of Aviation Safety

As Head of Aviation Safety at Airbus Helicopters my responsibility is to continually challenge and improve flight safety for the thousands of men and women around the world who are transported in our aircraft every day. Their welfare is at the heart of everything we do.

We work closely with customers, suppliers, manufacturers and key organizations such as the International Helicopter Safety Team and HeliOffshore, two global bodies working to enhance flight safety. We believe collaboration and partnership are critical to making advances in safety.

Over the past two years, Airbus Helicopters has worked closely with the Accident Investigation Board Norway (AIBN) in the context of the LN-OJF accident.  

In parallel, and in full cooperation with the European Aviation Safety Agency, Airbus Helicopters has been fully committed to learning as much as possible from the accident as part of our unerring commitment to product safety and continuing airworthiness. We invested considerable time and resources in testing the design, production and maintenance of the H225 to fully understand the cause of this tragic accident.

The Accident Investigation team has identified the most probable cause of the accident as a crack in a gear wheel in the main transmission box: a hard particle caused a scratch on a roller that, due to local overloading, led to a micro pitted line on the bearing roller and outer race. This progressively damaged the outer race of the gear while producing very few spalling particles which were not detected and ultimately led to its cracking.

Prior to 2016, the available degree of scientific and technical knowledge meant it was neither foreseeable nor foreseen that a crack in a plant gear could propagate in a sub-layer, and as a result generate very low levels of detectable particles.

With knowledge gained from this investigation, Airbus Helicopters has introduced a series of safety measures on the H225. Some of the technology that has been developed is ground-breaking for the helicopter industry.

Airbus Helicopters will continue to pursue innovations and improve safety standards through a proactive approach that sees us challenge internally everything we do. Work on a number of potential improvements to the H225 are in progress, and I remain optimistic that this concerted and complex work will yield new advances.

Gilles Bruniaux, Head of Aviation Safety

AIBN Final Report recommendation 12

The Accident Investigation Board Norway’s (AIBN) final report concludes with a series of recommendations for improving safety in the industry. Recommendation 12 addresses Airbus Helicopters and the redesign the H225 gearbox – so what have we done?

We have implemented continuous improvements to the gearbox’s design robustness through a series of new features. These include:

  • Reduction in the risk of outer race spalling by replacing planet gears equipped with FAG types to SNR, while at the same time reducing the life limit of these bearings.
  • Improved capture of particles in the oil with the introduction of a new full flow magnetic plug (FFMP) that increases the capture rate from 12% to 50%.
  • Strengthened inspection criteria and equipment allowing a more detailed analysis of these particles, including very small ones through the reduction in the size of the defined surface for the epicyclic module removal from surface to 3mm2.

We won’t stop here, and have also begun work on a number of potential improvements to the gearbox. This work is meticulous, painstaking and ambitious in nature and has yet to reach a sufficient level of maturity for final decisions to be made and announced at this moment in time.

Possible improvements under consideration include a research project to explore the potential for widening the scope and capability of Airbus Helicopters’ future Health and Usage Monitoring System (HUMS) to provide earlier detection of potential problems with the moving components inside transmissions.

Summary of H225 LN-OJF investigation

Third-party statements and reports

Third-party statements and reports regarding the accident investigation can be found on the following websites:

European Aviation Safety Agency (EASA)
Accident Investigation Board Norway (AIBN)
UK Civil Aviation Authority
Norwegian Civil Aviation Authority (Luftfartsilsynet) 
 
 

Super Puma Information Centre

Super Puma Information Centre

LN-OJF accident investigation status

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