The European Aviation Safety Agency (EASA) takes note of the publication today by the Accident Investigation Board Norway (AIBN) of the investigation report of the tragic accident of an Airbus Helicopters EC225 (registration number LN-OJF) which occurred on 29 April 2016 in Norway.
The Agency’s thoughts remain with the families and friends of the victims of this tragic accident.
EASA acknowledges the significant work of the AIBN to carry out an extensive investigation into the accident of LN-OJF.
While the final report contains a number of opinions and hypotheses, in relation to the actions taken after the G-REDL accident and Return To Service (RTS), it is important to consider these in relation to what was known at the time.
Actions after the accident of G-REDL
The investigation on the G-REDL accident did not establish the root cause of the gear fatigue failure because several parts were not recovered. However, there was evidence of spalling occurring before the accident, including the detection of a gear particle by the maintenance organisation. This led to the decisions allowing increased detection of particles by recurrent maintenance.
The decisions taken by EASA after the G-REDL accident were based on the knowledge available at the time, and the actions put in place were justified and commonly agreed. The AIBN report now identifies micro pitting as initiating the crack that, with limited spalling, led to the gear failure in the case of LN-OJF. This had not been identified with respect to the G-REDL accident investigation or analysis.
Actions after the accident to LN-OJF and the Return to Service
The RTS consisted of a number of mandatory airworthiness actions meeting the safety objectives as defined in Annex 1 (Part 21) of Commission Regulation (EU) No 748/2012.
The RTS was a first step in a sequence of actions that were foreseen in the associated Continuing Airworthiness Review Item (CARI) having the objective to consolidate and develop further safety improvements for the mid- and longer term. This means that the initial actions which were suitable in the short to medium term would be replaced by less maintenance intensive solutions.
From the AIBN report, EASA understands that the investigation did not reveal any facts or evidence available at the time that would invalidate the basis for the RTS.
Finally, EASA notes that the design, certification and continued airworthiness aspects of the Main Gear Box have been the main focus of this investigation. While EASA concurs with the AIBN’s final report regarding the most likely fracture mechanism, all the possible contributing factors to the failure initiation should still be considered relevant, even if the likelihood is considered remote or circumstantial by the AIBN. EASA will continue to take actions to address all such possible risks where considered necessary.
Safety is EASA’s mission and utmost priority. We will continue developing our safety plan with improvements stemming from this report.
