EC225 crash near Bergen, Norway April 2016
FB,
Tis HC that is lamenting the loss of a screen while handling Malfunctions/Emergencies.
I am asking if it is impossible to garner necessary information by means of looking at the other pilots screens or back up instruments?
Merely asking why HC perceives it to be such a problem!
Tis HC that is lamenting the loss of a screen while handling Malfunctions/Emergencies.
I am asking if it is impossible to garner necessary information by means of looking at the other pilots screens or back up instruments?
Merely asking why HC perceives it to be such a problem!
I would be far more concerned about hidden screens....that layered as malfunctions occur and you have to work your way down through the stack because the system does not present the most critical failure ahead of all of the others
Hi SASless, hi Megan,
some words in advance.
Pilots still use Brain 1.0 which was updated last ????
The job of the pilot is to aviate, navigate, communicate and when all this is done he wants to monitor trends with an occasional glance on the instruments?
The computer can do this much better - and it shows a misunderstanding of the systems, when someone thinks, you only get a warning, when a red line is reached
The computer records several times a second the values, compares them in relation to ambient conditions (pressure/temperature).
It does it regardless who is flying in the morning, in the afternoon or the night and therefore can detect trends much earlier than a pilot.
Depending on the rules it it also possible to compare values with other aircraft from the same operator or even worldwide for that model.
The idea behind that is to reduce pilot workload so he can do, what he is there for, flying the bird, looking out, talking to airtraffic and so on.
But it also requires a fullout understanding, what to find where, if needed.
There can be a problem with pilots with an old mindset (the ones, which have an mobile phone but no smartphone i.e.)
You need to „play“ with the system and the pages, to stay current, where to find and/or alter what you want/need.
The most important information you get with either one or at least two button presses.
Reconfiguration, altering times and so on takes a few more steps.
If one only uses the daily operation screens he might have trouble finding the right ones, when the stress level is higher.
The modern pilot has to adopt, change from a manual worker to a system manager.
But to manage the system, one has to understand how it works and there are some shortcomings with some pilots, not willing to go through a manual which is three times as thick as the old ones ....
If you open minded, you will see how much assistance you can get and if you use it, you can sit back and let bird do the work, relaxed enjoying the ride...
some words in advance.
Pilots still use Brain 1.0 which was updated last ????
The job of the pilot is to aviate, navigate, communicate and when all this is done he wants to monitor trends with an occasional glance on the instruments?
The computer can do this much better - and it shows a misunderstanding of the systems, when someone thinks, you only get a warning, when a red line is reached
The computer records several times a second the values, compares them in relation to ambient conditions (pressure/temperature).
It does it regardless who is flying in the morning, in the afternoon or the night and therefore can detect trends much earlier than a pilot.
Depending on the rules it it also possible to compare values with other aircraft from the same operator or even worldwide for that model.
The idea behind that is to reduce pilot workload so he can do, what he is there for, flying the bird, looking out, talking to airtraffic and so on.
But it also requires a fullout understanding, what to find where, if needed.
There can be a problem with pilots with an old mindset (the ones, which have an mobile phone but no smartphone i.e.)
You need to „play“ with the system and the pages, to stay current, where to find and/or alter what you want/need.
The most important information you get with either one or at least two button presses.
Reconfiguration, altering times and so on takes a few more steps.
If one only uses the daily operation screens he might have trouble finding the right ones, when the stress level is higher.
The modern pilot has to adopt, change from a manual worker to a system manager.
But to manage the system, one has to understand how it works and there are some shortcomings with some pilots, not willing to go through a manual which is three times as thick as the old ones ....
If you open minded, you will see how much assistance you can get and if you use it, you can sit back and let bird do the work, relaxed enjoying the ride...
A prime contributor to an industrial accident in our company that caused deaths and injuries, and left the community without gas for two weeks. Besides, I like to be able to see trends, I don't wish to be informed when the software decides a pressure or temperature has exceeded some preset limit, I want to see it rising or falling from its normal setting, I know regular scanning of such mundane items is not much taught.
Several folks seem to have no problem with the design, function, and handiness of the current systems in use.
HC, on the other hand, does seem to have an issue with at least one system.
Which view is the most correct?
Are all of you on the same page but saying it differently?
The way to answer my questions is to discuss HC's statement of concern.....as he is the one that raised the issue and I am just considering what he is saying.
I suggest one perspective is he is comparing the 225 Displays to the 175's and is suggesting the 175 was a step backwards.
How does the 225 and 175 differ and is the "newer" system less Pilot friendly?
HC, on the other hand, does seem to have an issue with at least one system.
Which view is the most correct?
Are all of you on the same page but saying it differently?
The way to answer my questions is to discuss HC's statement of concern.....as he is the one that raised the issue and I am just considering what he is saying.
I suggest one perspective is he is comparing the 225 Displays to the 175's and is suggesting the 175 was a step backwards.
How does the 225 and 175 differ and is the "newer" system less Pilot friendly?
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HC....Having a PM looking over your shoulder is nice....not necessary.
The PM can relieve the PF of some of that stress by analyzing and troubleshooting and offering up a plan of action while the PF.....flies the aircraft....right?
We did all this Single Pilot long before "Screens" and automation were heard of and it worked.
Do you reckon Pilots...PM or PF are less capable today because of the very Technological advances and changes in Training/Cockpit Procedures?
Are they really becoming "Children of the Magenta"?
The PM can relieve the PF of some of that stress by analyzing and troubleshooting and offering up a plan of action while the PF.....flies the aircraft....right?
We did all this Single Pilot long before "Screens" and automation were heard of and it worked.
Do you reckon Pilots...PM or PF are less capable today because of the very Technological advances and changes in Training/Cockpit Procedures?
Are they really becoming "Children of the Magenta"?
Yes I had a jolly in a 175 a few years ago so I know it is nice to fly! But that was the point when I noticed the screens weren't optimal. Obviously one can cope with only 4 screens, but I still maintain 5 would have better. Surely you can see that if you are used to 2 screens displaying flight info, and suddenly in an emergency you are down to 1 whilst the other chap still has 2, you are worse off than if you had the extra one because you not only have an abnormal screen setup to display the flight (instrument approach etc) but you also now have the stress of an emergency to deal with?
The Thread has drifted from the 225 crash....as often happens.
The 175 does this for you. ENG TREND/HYD TREND etc etc, there really is no need to have a set of gauges up for you to monitor. As FB said above, it will do it better than you ever will. And if it loses the ability to monitor the trends, it will tell you that too!
My only point is that when there IS an emergency, let's say a transmission oil issue, one would then I think want to monitor the gauge and thus a screen is lost from its normal function (providing PM with the same info as PF). So 99.999% of the time the concept is fine. For that 0.001% of the time when the crew are maxxed out with both an emergency and say an instrument approach, a 5th screen would have been better.
I'm not sure there is any more to be said directly on the thread subject matter. (if there is, please do so and we will all shut up!). But actually what is behind this thread drift is pointing out that other factors in helicopter design can be just as relevant to overall safety as one fatal flaw that is nevertheless extremely unlikely to manifest itself. Good HMI and an autopilot that does its best to prevent the pilots flying into the sea may result in fewer fatal accidents than eliminating a type that has a one in a million flight hours (or whatever) chance of losing its rotor head. Of course the 175 does have very good HMI and autopilot, my point was only that I wish it could have been slightly better (for 2 pilot IFR use) by having a 5th screen. Its mechanical reliability and possible presence of a fatal flaw does of course remain to be seen, as with all new types.
Several folks seem to have no problem with the design, function, and handiness of the current systems in use.
HC, on the other hand, does seem to have an issue with at least one system.
Which view is the most correct?
Are all of you on the same page but saying it differently?
The way to answer my questions is to discuss HC's statement of concern.....as he is the one that raised the issue and I am just considering what he is saying.
I suggest one perspective is he is comparing the 225 Displays to the 175's and is suggesting the 175 was a step backwards.
How does the 225 and 175 differ and is the "newer" system less Pilot friendly?
HC, on the other hand, does seem to have an issue with at least one system.
Which view is the most correct?
Are all of you on the same page but saying it differently?
The way to answer my questions is to discuss HC's statement of concern.....as he is the one that raised the issue and I am just considering what he is saying.
I suggest one perspective is he is comparing the 225 Displays to the 175's and is suggesting the 175 was a step backwards.
How does the 225 and 175 differ and is the "newer" system less Pilot friendly?
We are back to the fundamental design concept difference between the French and the US - the former believe all pilots are stupid and best to give them as little information as possible so as to reduce the opportunities for messing up, the latter believe in telling the pilots absolutely everything possible and leaving them to sort it out (after all, they are all descended from Chuck Yeager). I am inclined to go along with the former philosophy!
Obviously the decision to not have a 5th screen was a cost-based one. There is plenty of room for it and when I raised my point with AH originally, it was implied that it would be an option in the future (don't know if that ever transpired). The 175 HMI is great, especially when compared to the competition from Italy and US, my point is only that it could so easily have been even better and that it wasn't I think is partly down to AH's lack of appreciation of the N Sea 2 pilot IFR role. The guys at the factory are more aligned with single pilot VFR.
Today it has been 3 months since the final report was published, including the 12 safety recommendations.
According to Regulation 996/2010 Article 18.1 "The addressee of a safety recommendation shall acknowledge receipt of the transmittal letter and inform the safety investigation authority which issued the recommendation within 90 days of the receipt of that letter, of the actions taken or under consideration, and where appropriate, of the time necessary for their completion and where no action is taken, the reasons therefor."
Hopefully that potentially interesting information will be available too all soon.
According to Regulation 996/2010 Article 18.1 "The addressee of a safety recommendation shall acknowledge receipt of the transmittal letter and inform the safety investigation authority which issued the recommendation within 90 days of the receipt of that letter, of the actions taken or under consideration, and where appropriate, of the time necessary for their completion and where no action is taken, the reasons therefor."
Hopefully that potentially interesting information will be available too all soon.
Follow-up of safety recommendations
Here are the replies to the 12 AIBN Safety recommendations that appear to have been received so far:
Safety recommendation SL No. 2018/01T
The failure mode, i.e. crack formation subsurface with limited spalling initiated from a surface damage, observed in the LN-OJF accident is currently not fully understood. The investigation has shown that the combination of material properties, surface treatment, design, operational loading environment and debris gave rise to a failure mode that was not previously anticipated or assessed.
The Accident Investigation Board Norway recommends that the European Aviation Safety Agency (EASA) commission research into crack development in high-loaded case-hardened bearings in aircraft applications. An aim of the research should be the prediction of the reduction in service-life and fatigue strength as a consequence of small surface damage such as micro-pits, wearmarks and roughness.
Reply from EASA
The Agency intends to commission a research project, the scope of which will include identification of rotor drive system critical parts and associated damage mechanisms, identification of significant design, operational and environmental parameters, identification and characterization of significant threats and recommendation of design standards to ensure flaw tolerant structural integrity. The research project is listed as RES.008 (Rotorcraft main gear box (MGB) design to guarantee integrity of critical parts and system architecture to prevent separation of the main rotor following any MGB failure) in the draft European Plan for Aviation Safety 2019-2023, which is currently undergoing consultation with the Agency's advisory bodies.
EASA status – Open
Safety recommendation SL No. 2018/02T
The MGB, which was later installed in LN-OJF, fell off a truck during transport. It was inspected, repaired and released for flight by Airbus Helicopters without detailed analysis of the potential effects on the critical characteristics of the MGB. The current regulatory framework for large rotorcraft does not make connections between the Instructions for Continued Airworthiness (ICA) and requirements for critical parts subject to an unusual event.
The Accident Investigation Board Norway recommends that the European Aviation Safety Agency (EASA) assess the need to amend the regulatory requirements with regard to procedures or Instructions for Continued Airworthiness (ICA) for critical parts on helicopters to maintain the design integrity after being subjected to any unusual event.
Reply from EASA
EASA will conduct a Preliminary Impact Assessment (PIA) in order to assess the need to amend the certification specifications for large rotorcraft (CS-29) with regard ·to procedures or instructions for continued airworthiness for critical parts on helicopters to maintain the design integrity after being subjected to any unusual event. Once the PIA is mature, stakeholders will be consulted. Consultation is expected to take place In 02Q2019.
Depending on the outcome of the PIA, EASA will include an appropriate task in the European Plan for Aviation Safety.
EASA status – Open
Safety recommendation SL No. 2018/03T
Rolling contact fatigue as observed in the LN-OJF accident was not considered during type certification, neither is it directly addressed in the current certification specifications.
The Accident Investigation Board Norway recommends that European Aviation Safety Agency (EASA) amend the Acceptable Means of Compliance (AMC) to the Certification Specifications for Large Rotorcraft (CS-29) in order to highlight the importance of different modes of component structural degradation and how these can affect crack initiation and propagation and hence fatigue life.
Reply from EASA
EASA will conduct a preliminary impact assessment (PIA) to assess the need to amend the Acceptable Means of Compliance (AMC) to the Certification Specifications for Large Rotorcraft (CS-29) in order to highlight the importance of different modes of component structural degradation and how these can affect crack init iation and propagation and hence fatigue life. The aim of such AMC could be to add specific reference to modes of component structural degradation related to rolling contact fatigue and how these can affect crack initiation and propagation and, hence, fatigue life. Once the PIA is mature, stakeholders will be consulted. Consultation is expected to take place in 02Q2019.
Depending on the outcome of the PIA, EASA will include an appropriate task in the European Plan for Aviation Safety.
In the meantime, EASA is already raising the issue during certification projects via a dedicated Certification Review Item (CRI) providing Interpretative Material to better assess the effect of rolling contact fatigue.
EASA status – Open
Safety recommendation SL No. 2018/04T
The chip detection system fitted to LN-OJF did not produce any warnings of the impending planet gear catastrophic failure, and the potential of detection was limited. The Certification Specifications for Large Rotorcraft (CS-29) do not specify the chip detection system’s functionality and performance.
The Accident Investigation Board Norway recommends that the European Aviation Safety Agency (EASA) revise the Certification Specifications for Large Rotorcraft (CS-29) to introduce requirements for MGB chip detection system performance.
Reply from EASA
EASA has recognised the need to improve certification specifications in CS-27 (small rotorcraft) and CS-29 (large rotorcraft) relating to Main Gear Box (MGB) chip detectors.
The current CS 27 /29.130S(a)(23) and CS 27 /29.1337(e) require chip detectors to provide a warning to the flight crew when particles of a sufficient size (or accumulation) are detected and are intended to allow the flight crew to check the correct operation of the relevant elements ' of the drive system.
EASA has conducted a Preliminary Impact Assessment (PIA) on the possible actions to improve the likelihood of detecting chips or particles in gearbox oil. The outcome of the PIA was the inclusion of a dedicated Rulemaking Task (RMT) 0725 in the draft European Plan for Aviation Safety (EPAS) 2019-2023 which is currently undergoing consultation with the Agency's advisory bodies.
The planned RMT.0725 will consider an amendment of the current certification specifications and their associated acceptable means of compliance for demonstrating that the chip detectors perform their intended function.
EASA status – Open
Safety recommendation SL No. 2018/05T
The LN-OJF accident was a result of a fatigue fracture in one of the eight second stage planet gears in the epicyclic module of the MGB, a critical part in which cracks developed subsurface to a catastrophic failure without being detected. It might not be possible to assess the fatigue reliability of internal MGB components, or design a warning system that works with sufficient efficiency and warning time, thus the MGB should be designed fail-safe.
The Accident Investigation Board Norway recommends that the European Aviation Safety Agency (EASA) develop MGB certification specifications for large rotorcraft to introduce a design requirement that no failure of internal MGB components should lead to a catastrophic failure.
Reply from EASA
The Agency understands that the objective of this Safety Recommendation is that future rotor drive system design requirements will ensure that "no failure of internal MGB components should lead to a catastrophic failure." However, such designs would be so radically different from existing transmission systems that their feasibility needs to be assessed.
EASA considers that the number of potentially catastrophic failure modes should be minimised. Accordingly, any component, the failure of which has a potentially catastrophic failure effect, should not be acceptable if the failure hazard severity can be mitigated to a reduced level and where such measures are considered to be technically feasible and economically justifiable.
It is clear that design choices regarding rotor drive system architecture and individual gearbox design will influence the number of potentially critical parts.
In order to better understand the significance of these design choices, research is planned within the scope of project RES.008 (Rotorcraft main gear box (MGB) design to guarantee integrity of critical parts and system architecture to prevent separation of the main rotor following any MGB failure) in the draft European Plan for Aviation Safety (EPAS) 2019-2023, which is currently under consultation with stakeholders.
EASA status – Open
Safety recommendation SL No. 2018/06T
The investigation into the accident to LN-OJF has revealed that the tests performed during the design and certification of the Airbus Helicopters EC 225 LP were in accordance with applicable regulations. However, with regard to the risks associated with offshore operations, there is a less stringent continued operational reliability test requirement for large rotorcraft compared with the Extended Operations and All Weather Operations regime for fixed wing aircraft.
The Accident Investigation Board Norway recommends that the European Aviation Safety Agency (EASA) develop regulations for engine and helicopter operational reliability systems, which could be applied to helicopters which carry out offshore and similar operations to improve safety outcomes.
Reply from EASA
EASA previously evaluated the suitability of the concept proposed in this safety recommendation, i.e. applying the ETOPS principles to helicopters conducting offshore operations, following the receipt of a safety recommendation from the CAA UK. At the end of 2015, EASA concluded that rulemaking was not deemed justified, owing to the differences in term of designs and operating conditions between helicopters and aeroplanes flying ETOPS.
EASA will re-evaluate its conclusion in the light of this safety recommendation. Depending on the results of the review of the concept, a preliminary impact assessment (PIA) may be prepared if deemed appropriate; the PIA would then review possible actions, including rulemaking, and a consultation of stakeholders would be performed.
EASA status – Open
Safety recommendation SL No. 2018/07T
The investigation into the accident to LN-OJF has found that only a few second stage planet gears in Airbus Helicopters EC 225 LP and AS 332 L2 ever reached their intended operational time before being rejected during overhaul inspections or non-scheduled MGB removals. The parts rejected against predefined maintenance criteria were not routinely examined and analysed by Airbus Helicopters.
The Accident Investigation Board Norway recommends that European Aviation Safety Agency (EASA) make sure that helicopter manufacturers review their Continuing Airworthiness Programme to ensure that critical components, which are found to be beyond serviceable limits, are examined so that the full nature of any damage and its effect on continued airworthiness is understood, either resulting in changes to the maintenance programme, or design as necessary, or driving a mitigation plan to prevent or minimise such damage in the future.
Reply from EASA
EASA will consider amending the Acceptable Means of Compliance (AMC) and Guidance Material (GM) to point 21.A.3A of Annex I (Part-21) to Commission Regulation (EU) No 748/2012, in order to clarify the obligations of Type Certificate Holders to ensure compliance with the requirement of "collecting, investigating and analysing reports of and information related to failures, malfunctions, defects or other occurrences which cause or might cause adverse effects on the continuing airworthiness of the product( ... )".
This will be performed within the frame of rulemaking task RMT.0031 dealing with the regular update of AMC/GM to Part-21. The next NPA is planned to be published 02Q2019.
EASA status – Open
Safety recommendation SL No. 2018/08T
The investigation into the accident to LN-OJF has found that only a few second stage planet gears in Airbus Helicopters EC 225 LP and AS 332 L2 ever reached their intended operational time limit before being rejected during overhaul inspections or non-scheduled MGB removals.
The Accident Investigation Board Norway recommends that the European Aviation Safety Agency (EASA) review and improve the existing provisions and procedures applicable to critical parts on helicopters in order to ensure design assumptions are correct throughout its service life.
Reply from EASA
EASA issued Certification Memorandum (CM) CM-S-007 in 2015. The purpose of this CM was to supplement the existing guidance for compliance with CS 27 /29.602 (Critical Parts), detailing the need for post certification actions to verify the continued integrity of Critical Parts.
These actions should ensure that critical parts are controlled throughout their service life in order to maintain the critical characteristics on which certification is based. In addition, the effectiveness of any associated design, maintenance and monitoring provisions, which either help ensure the continued integrity or provide advance indication of impending failure of critical parts, should be assessed.
EASA will conduct a Preliminary Impact Assessment (PIA) in order to assess the potential safety benefit and economic: impact of a number of changes to improve the Guidance Material applicable to CS 29.602.
Consideration will also be made to include the provisions of CM-S-007 within the Acceptable Means of Compliance of CS-29 'Book 2'.
Consultation is expected to take place in 02Q2020.
EASA status – Open
Safety recommendation SL No. 2018/09T
The investigation into the accident to LN-OJF has demonstrated that a critical structural component could fail totally without any pre-detection by the existing monitoring means.
The Accident Investigation Board Norway recommends that the European Aviation Safety Agency (EASA) research methods for improving the detection of component degradation in helicopter epicyclic planet gear bearings.
Reply from EASA
The Agency intends to commission a research project into rotorcraft gearbox health monitoring. The purpose of this research will be to investigate the use of new technologies, including both hardware and methods of analysis, to improve prognostic health monitoring capability for tilt rotor, helicopter and hybrid aircraft gearbox failures.
The scope of this research will include health monitoring of epicyclic gearbox components. This project is listed as RES.011 (Helicopter, tilt rotor and hybrid aircraft Gearbox health monitoring - ln-situ failure detection ) in the draft European Plan for Aviation Safety 2019-2023 which is currently undergoing consultation with the Agency's advisory bodies.
EASA status – Open
Safety recommendation SL No. 2018/10T
During the investigation into the accident to LN-OJF, considerable time and resources by the AIBN has been drawn to request, wait for release acceptance and review of design and certification documents.
The Accident Investigation Board Norway recommends that the European Commission (DG MOVE) in collaboration with European Aviation Safety Agency (EASA) evaluates the means for ensuring that investigation authorities have effectively free access to any relevant information or records held by the owner, the certificate holder of the type design, the responsible maintenance organisation, the training organisation, the operator or the manufacturer of the aircraft, the authorities responsible for civil aviation, EASA, ANSPs and airport operators.
No reply appears to have been received
Safety recommendation SL No. 2018/11T
During the investigation into the accident to LN-OJF, considerable time and resources by the AIBN has been drawn to request, wait for release acceptance and review of design and certification documents. ICAO Annex 13 Chapter 5.12 does not refer explicitly to the protection of sensitive proprietary information regarding design and certification.
The Accident Investigation Board Norway recommends that the International Civil Aviation Organisation (ICAO) evaluates the means for ensuring that investigation authorities have effectively free access to any relevant information or records held by the owner, the certificate holder of the type design, the responsible maintenance organisation, the training organisation, the operator or the manufacturer of the aircraft, the authorities responsible for civil aviation, certification authorities, ANSPs and airport operators.
Reply from ICAO:
Amendment 16 to Annex 13 — Aircraft Accident and Incident Investigation, upgrades Recommendation 5.4.3 to a Standard and will become applicable on 8 November 2018. Standard 5.4.3 reads that “A State shall ensure that any investigations conducted under the provisions of this Annex have unrestricted access to all evidential material without delay.” And Standard 5.6 states that “The investigator-in—charge shall have unhampered access to the wreckage and all relevant material, including flight recorders and ATS records, and shall have unrestricted control over it to ensure that a detailed examination can be made without delay by authorized personnel participating in the investigation.”
Annex 13, 5.18 provides for the participation of accredited representatives appointed by the various States taking part in an investigation. Accredited representatives are entitled to appoint advisers who, in turn, would be able to obtain relevant information stemming from the aircraft manufacturer, type certification holder, operator, maintenance organizations and other information necessary for the investigation.
It is therefore believed that Annex 13 provisions, together With associated guidance material, provide the means to ensure that accident investigation authorities have timely access to relevant information and pertinent records necessary for the investigation.
Safety recommendation SL No. 2018/12T
The LN-OJF accident was a result of a fatigue fracture in one of the eight second stage planet gears in the epicyclic module of the MGB, a critical part in which cracks developed subsurface to a catastrophic failure without being detected. With the knowledge from this investigation, all effort should lead to a robust design in which a single load path should demonstrate compliance to CS 29.601(a), 29.602 and 29.571 without compromising its structural integrity and not only by depending on detection systems or maintenance checks.
The Accident Investigation Board Norway recommends that Airbus Helicopters revise the type design to improve the robustness, reliability and safety of the main gearbox in AS 332 L2 and EC 225 LP.
Reply from Airbus Helicopters:
Airbus is currently defining, together with authorities, the perimeter of a future set of evolutions in order to improve the robustness, the reliability and safety of the main gearbox in AS332 L2 and EC225 LP.
The associated roadmap will be presented beginning of 2019.
Here are the replies to the 12 AIBN Safety recommendations that appear to have been received so far:
Safety recommendation SL No. 2018/01T
The failure mode, i.e. crack formation subsurface with limited spalling initiated from a surface damage, observed in the LN-OJF accident is currently not fully understood. The investigation has shown that the combination of material properties, surface treatment, design, operational loading environment and debris gave rise to a failure mode that was not previously anticipated or assessed.
The Accident Investigation Board Norway recommends that the European Aviation Safety Agency (EASA) commission research into crack development in high-loaded case-hardened bearings in aircraft applications. An aim of the research should be the prediction of the reduction in service-life and fatigue strength as a consequence of small surface damage such as micro-pits, wearmarks and roughness.
Reply from EASA
The Agency intends to commission a research project, the scope of which will include identification of rotor drive system critical parts and associated damage mechanisms, identification of significant design, operational and environmental parameters, identification and characterization of significant threats and recommendation of design standards to ensure flaw tolerant structural integrity. The research project is listed as RES.008 (Rotorcraft main gear box (MGB) design to guarantee integrity of critical parts and system architecture to prevent separation of the main rotor following any MGB failure) in the draft European Plan for Aviation Safety 2019-2023, which is currently undergoing consultation with the Agency's advisory bodies.
EASA status – Open
Safety recommendation SL No. 2018/02T
The MGB, which was later installed in LN-OJF, fell off a truck during transport. It was inspected, repaired and released for flight by Airbus Helicopters without detailed analysis of the potential effects on the critical characteristics of the MGB. The current regulatory framework for large rotorcraft does not make connections between the Instructions for Continued Airworthiness (ICA) and requirements for critical parts subject to an unusual event.
The Accident Investigation Board Norway recommends that the European Aviation Safety Agency (EASA) assess the need to amend the regulatory requirements with regard to procedures or Instructions for Continued Airworthiness (ICA) for critical parts on helicopters to maintain the design integrity after being subjected to any unusual event.
Reply from EASA
EASA will conduct a Preliminary Impact Assessment (PIA) in order to assess the need to amend the certification specifications for large rotorcraft (CS-29) with regard ·to procedures or instructions for continued airworthiness for critical parts on helicopters to maintain the design integrity after being subjected to any unusual event. Once the PIA is mature, stakeholders will be consulted. Consultation is expected to take place In 02Q2019.
Depending on the outcome of the PIA, EASA will include an appropriate task in the European Plan for Aviation Safety.
EASA status – Open
Safety recommendation SL No. 2018/03T
Rolling contact fatigue as observed in the LN-OJF accident was not considered during type certification, neither is it directly addressed in the current certification specifications.
The Accident Investigation Board Norway recommends that European Aviation Safety Agency (EASA) amend the Acceptable Means of Compliance (AMC) to the Certification Specifications for Large Rotorcraft (CS-29) in order to highlight the importance of different modes of component structural degradation and how these can affect crack initiation and propagation and hence fatigue life.
Reply from EASA
EASA will conduct a preliminary impact assessment (PIA) to assess the need to amend the Acceptable Means of Compliance (AMC) to the Certification Specifications for Large Rotorcraft (CS-29) in order to highlight the importance of different modes of component structural degradation and how these can affect crack init iation and propagation and hence fatigue life. The aim of such AMC could be to add specific reference to modes of component structural degradation related to rolling contact fatigue and how these can affect crack initiation and propagation and, hence, fatigue life. Once the PIA is mature, stakeholders will be consulted. Consultation is expected to take place in 02Q2019.
Depending on the outcome of the PIA, EASA will include an appropriate task in the European Plan for Aviation Safety.
In the meantime, EASA is already raising the issue during certification projects via a dedicated Certification Review Item (CRI) providing Interpretative Material to better assess the effect of rolling contact fatigue.
EASA status – Open
Safety recommendation SL No. 2018/04T
The chip detection system fitted to LN-OJF did not produce any warnings of the impending planet gear catastrophic failure, and the potential of detection was limited. The Certification Specifications for Large Rotorcraft (CS-29) do not specify the chip detection system’s functionality and performance.
The Accident Investigation Board Norway recommends that the European Aviation Safety Agency (EASA) revise the Certification Specifications for Large Rotorcraft (CS-29) to introduce requirements for MGB chip detection system performance.
Reply from EASA
EASA has recognised the need to improve certification specifications in CS-27 (small rotorcraft) and CS-29 (large rotorcraft) relating to Main Gear Box (MGB) chip detectors.
The current CS 27 /29.130S(a)(23) and CS 27 /29.1337(e) require chip detectors to provide a warning to the flight crew when particles of a sufficient size (or accumulation) are detected and are intended to allow the flight crew to check the correct operation of the relevant elements ' of the drive system.
EASA has conducted a Preliminary Impact Assessment (PIA) on the possible actions to improve the likelihood of detecting chips or particles in gearbox oil. The outcome of the PIA was the inclusion of a dedicated Rulemaking Task (RMT) 0725 in the draft European Plan for Aviation Safety (EPAS) 2019-2023 which is currently undergoing consultation with the Agency's advisory bodies.
The planned RMT.0725 will consider an amendment of the current certification specifications and their associated acceptable means of compliance for demonstrating that the chip detectors perform their intended function.
EASA status – Open
Safety recommendation SL No. 2018/05T
The LN-OJF accident was a result of a fatigue fracture in one of the eight second stage planet gears in the epicyclic module of the MGB, a critical part in which cracks developed subsurface to a catastrophic failure without being detected. It might not be possible to assess the fatigue reliability of internal MGB components, or design a warning system that works with sufficient efficiency and warning time, thus the MGB should be designed fail-safe.
The Accident Investigation Board Norway recommends that the European Aviation Safety Agency (EASA) develop MGB certification specifications for large rotorcraft to introduce a design requirement that no failure of internal MGB components should lead to a catastrophic failure.
Reply from EASA
The Agency understands that the objective of this Safety Recommendation is that future rotor drive system design requirements will ensure that "no failure of internal MGB components should lead to a catastrophic failure." However, such designs would be so radically different from existing transmission systems that their feasibility needs to be assessed.
EASA considers that the number of potentially catastrophic failure modes should be minimised. Accordingly, any component, the failure of which has a potentially catastrophic failure effect, should not be acceptable if the failure hazard severity can be mitigated to a reduced level and where such measures are considered to be technically feasible and economically justifiable.
It is clear that design choices regarding rotor drive system architecture and individual gearbox design will influence the number of potentially critical parts.
In order to better understand the significance of these design choices, research is planned within the scope of project RES.008 (Rotorcraft main gear box (MGB) design to guarantee integrity of critical parts and system architecture to prevent separation of the main rotor following any MGB failure) in the draft European Plan for Aviation Safety (EPAS) 2019-2023, which is currently under consultation with stakeholders.
EASA status – Open
Safety recommendation SL No. 2018/06T
The investigation into the accident to LN-OJF has revealed that the tests performed during the design and certification of the Airbus Helicopters EC 225 LP were in accordance with applicable regulations. However, with regard to the risks associated with offshore operations, there is a less stringent continued operational reliability test requirement for large rotorcraft compared with the Extended Operations and All Weather Operations regime for fixed wing aircraft.
The Accident Investigation Board Norway recommends that the European Aviation Safety Agency (EASA) develop regulations for engine and helicopter operational reliability systems, which could be applied to helicopters which carry out offshore and similar operations to improve safety outcomes.
Reply from EASA
EASA previously evaluated the suitability of the concept proposed in this safety recommendation, i.e. applying the ETOPS principles to helicopters conducting offshore operations, following the receipt of a safety recommendation from the CAA UK. At the end of 2015, EASA concluded that rulemaking was not deemed justified, owing to the differences in term of designs and operating conditions between helicopters and aeroplanes flying ETOPS.
EASA will re-evaluate its conclusion in the light of this safety recommendation. Depending on the results of the review of the concept, a preliminary impact assessment (PIA) may be prepared if deemed appropriate; the PIA would then review possible actions, including rulemaking, and a consultation of stakeholders would be performed.
EASA status – Open
Safety recommendation SL No. 2018/07T
The investigation into the accident to LN-OJF has found that only a few second stage planet gears in Airbus Helicopters EC 225 LP and AS 332 L2 ever reached their intended operational time before being rejected during overhaul inspections or non-scheduled MGB removals. The parts rejected against predefined maintenance criteria were not routinely examined and analysed by Airbus Helicopters.
The Accident Investigation Board Norway recommends that European Aviation Safety Agency (EASA) make sure that helicopter manufacturers review their Continuing Airworthiness Programme to ensure that critical components, which are found to be beyond serviceable limits, are examined so that the full nature of any damage and its effect on continued airworthiness is understood, either resulting in changes to the maintenance programme, or design as necessary, or driving a mitigation plan to prevent or minimise such damage in the future.
Reply from EASA
EASA will consider amending the Acceptable Means of Compliance (AMC) and Guidance Material (GM) to point 21.A.3A of Annex I (Part-21) to Commission Regulation (EU) No 748/2012, in order to clarify the obligations of Type Certificate Holders to ensure compliance with the requirement of "collecting, investigating and analysing reports of and information related to failures, malfunctions, defects or other occurrences which cause or might cause adverse effects on the continuing airworthiness of the product( ... )".
This will be performed within the frame of rulemaking task RMT.0031 dealing with the regular update of AMC/GM to Part-21. The next NPA is planned to be published 02Q2019.
EASA status – Open
Safety recommendation SL No. 2018/08T
The investigation into the accident to LN-OJF has found that only a few second stage planet gears in Airbus Helicopters EC 225 LP and AS 332 L2 ever reached their intended operational time limit before being rejected during overhaul inspections or non-scheduled MGB removals.
The Accident Investigation Board Norway recommends that the European Aviation Safety Agency (EASA) review and improve the existing provisions and procedures applicable to critical parts on helicopters in order to ensure design assumptions are correct throughout its service life.
Reply from EASA
EASA issued Certification Memorandum (CM) CM-S-007 in 2015. The purpose of this CM was to supplement the existing guidance for compliance with CS 27 /29.602 (Critical Parts), detailing the need for post certification actions to verify the continued integrity of Critical Parts.
These actions should ensure that critical parts are controlled throughout their service life in order to maintain the critical characteristics on which certification is based. In addition, the effectiveness of any associated design, maintenance and monitoring provisions, which either help ensure the continued integrity or provide advance indication of impending failure of critical parts, should be assessed.
EASA will conduct a Preliminary Impact Assessment (PIA) in order to assess the potential safety benefit and economic: impact of a number of changes to improve the Guidance Material applicable to CS 29.602.
Consideration will also be made to include the provisions of CM-S-007 within the Acceptable Means of Compliance of CS-29 'Book 2'.
Consultation is expected to take place in 02Q2020.
EASA status – Open
Safety recommendation SL No. 2018/09T
The investigation into the accident to LN-OJF has demonstrated that a critical structural component could fail totally without any pre-detection by the existing monitoring means.
The Accident Investigation Board Norway recommends that the European Aviation Safety Agency (EASA) research methods for improving the detection of component degradation in helicopter epicyclic planet gear bearings.
Reply from EASA
The Agency intends to commission a research project into rotorcraft gearbox health monitoring. The purpose of this research will be to investigate the use of new technologies, including both hardware and methods of analysis, to improve prognostic health monitoring capability for tilt rotor, helicopter and hybrid aircraft gearbox failures.
The scope of this research will include health monitoring of epicyclic gearbox components. This project is listed as RES.011 (Helicopter, tilt rotor and hybrid aircraft Gearbox health monitoring - ln-situ failure detection ) in the draft European Plan for Aviation Safety 2019-2023 which is currently undergoing consultation with the Agency's advisory bodies.
EASA status – Open
Safety recommendation SL No. 2018/10T
During the investigation into the accident to LN-OJF, considerable time and resources by the AIBN has been drawn to request, wait for release acceptance and review of design and certification documents.
The Accident Investigation Board Norway recommends that the European Commission (DG MOVE) in collaboration with European Aviation Safety Agency (EASA) evaluates the means for ensuring that investigation authorities have effectively free access to any relevant information or records held by the owner, the certificate holder of the type design, the responsible maintenance organisation, the training organisation, the operator or the manufacturer of the aircraft, the authorities responsible for civil aviation, EASA, ANSPs and airport operators.
No reply appears to have been received
Safety recommendation SL No. 2018/11T
During the investigation into the accident to LN-OJF, considerable time and resources by the AIBN has been drawn to request, wait for release acceptance and review of design and certification documents. ICAO Annex 13 Chapter 5.12 does not refer explicitly to the protection of sensitive proprietary information regarding design and certification.
The Accident Investigation Board Norway recommends that the International Civil Aviation Organisation (ICAO) evaluates the means for ensuring that investigation authorities have effectively free access to any relevant information or records held by the owner, the certificate holder of the type design, the responsible maintenance organisation, the training organisation, the operator or the manufacturer of the aircraft, the authorities responsible for civil aviation, certification authorities, ANSPs and airport operators.
Reply from ICAO:
Amendment 16 to Annex 13 — Aircraft Accident and Incident Investigation, upgrades Recommendation 5.4.3 to a Standard and will become applicable on 8 November 2018. Standard 5.4.3 reads that “A State shall ensure that any investigations conducted under the provisions of this Annex have unrestricted access to all evidential material without delay.” And Standard 5.6 states that “The investigator-in—charge shall have unhampered access to the wreckage and all relevant material, including flight recorders and ATS records, and shall have unrestricted control over it to ensure that a detailed examination can be made without delay by authorized personnel participating in the investigation.”
Annex 13, 5.18 provides for the participation of accredited representatives appointed by the various States taking part in an investigation. Accredited representatives are entitled to appoint advisers who, in turn, would be able to obtain relevant information stemming from the aircraft manufacturer, type certification holder, operator, maintenance organizations and other information necessary for the investigation.
It is therefore believed that Annex 13 provisions, together With associated guidance material, provide the means to ensure that accident investigation authorities have timely access to relevant information and pertinent records necessary for the investigation.
Safety recommendation SL No. 2018/12T
The LN-OJF accident was a result of a fatigue fracture in one of the eight second stage planet gears in the epicyclic module of the MGB, a critical part in which cracks developed subsurface to a catastrophic failure without being detected. With the knowledge from this investigation, all effort should lead to a robust design in which a single load path should demonstrate compliance to CS 29.601(a), 29.602 and 29.571 without compromising its structural integrity and not only by depending on detection systems or maintenance checks.
The Accident Investigation Board Norway recommends that Airbus Helicopters revise the type design to improve the robustness, reliability and safety of the main gearbox in AS 332 L2 and EC 225 LP.
Reply from Airbus Helicopters:
Airbus is currently defining, together with authorities, the perimeter of a future set of evolutions in order to improve the robustness, the reliability and safety of the main gearbox in AS332 L2 and EC225 LP.
The associated roadmap will be presented beginning of 2019.
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https://www.flightglobal.com/news/ar...225-cr-460792/
An interesting development, although the impact on the 225 market may take some time to understand.
An interesting development, although the impact on the 225 market may take some time to understand.
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Article here:Workers dubbed the Super Puma helicopter model, once dominant in the sector, the “flying coffin” after the crash off the island of Turoy in 2016.
It was the last straw for the sector, which had endured a spate of crashes since 2009, claiming 33 lives, with the Super Puma, which has not been in service in the North Sea for the last five years.
Jake Molloy, regional organiser of the RMT union, said: “For a lot of the guys it would instil terror to get into that particular model of aircraft and I think a lot of guys breathe easy at the thought that we’re not using them.
“I recall it, like I’ve recalled so many down the years, with deep despair that life can so tragically be lost. It really is an event that I wouldn’t want anyone to experience. I’ve lost good friends and colleagues through the years in events like this.
“It sits in the forefront of your mind all the time. Even sitting in the garden, as I am now, seeing them flying overhead, those thoughts come back to you. They never go away.”
© AIBN
1/3 – The main rotor detached from the helicopter.On April 29, 2016, a CHC-operated Super Puma went down while carrying oil workers from the Gullfaks B platform to Bergen Airport.
Iain Stuart, 41, from Laurencekirk, was among those killed in the crash off Turoy in Norway, taking place after the main rotor detached from the helicopter.
In the last seconds of its journey the chopper fell 2,000 feet, with witnesses describing an “explosion in the sky”.
The rotor broke off due to a “fatigue fracture” in a “second stage planet gear” in the main rotor gearbox.
Investigators later said it was probable that the failure was caused by tiny pieces of debris wearing away at the component. The system installed for detecting the particles was “inadequate”, they added.
A spokesman said: “All of us were shocked and saddened by this event and we continue to extend our sincere and profound sympathies to the families of the bereaved.”
Despite the Super Puma crashes, though, many pilots still back the aircraft, which Airbus continues to sell widely in industries such as law enforcement and search and rescue.
Mr Molloy, of RMT, said, for whatever reason, the North Sea appears to have been its “Achilles heel”.
Along with Norwegian colleagues, trade unions in the UK plan to maintain a position that the Super Puma cannot fly again in the industry.
“I think you’d find a considerable pushback from the offshore workforce for that ever to be suggested in any case,” he said.
“Certainly this generation won’t be climbing into a Super Puma anytime soon.”
The victims were Iain Stuart, 41, Behnam Ahmadi, 54, Arild Fossedal, 43, Ole Magnar Kvamme, 60, Odd Geir Turøy, 54, Otto Mikal Vasstveit, 54, Kjetil Wathne, 51, Michele Vimercati, 44, Tommas Helland, 50, Espen Samuelsen, 35, Lyder Martin Telle, 57, and Olav Bastiansen, 57 and Silje Ye Rim Veivåg Krogsæther, 32.
It was the last straw for the sector, which had endured a spate of crashes since 2009, claiming 33 lives, with the Super Puma, which has not been in service in the North Sea for the last five years.
Jake Molloy, regional organiser of the RMT union, said: “For a lot of the guys it would instil terror to get into that particular model of aircraft and I think a lot of guys breathe easy at the thought that we’re not using them.
“I recall it, like I’ve recalled so many down the years, with deep despair that life can so tragically be lost. It really is an event that I wouldn’t want anyone to experience. I’ve lost good friends and colleagues through the years in events like this.
“It sits in the forefront of your mind all the time. Even sitting in the garden, as I am now, seeing them flying overhead, those thoughts come back to you. They never go away.”
© AIBN
1/3 – The main rotor detached from the helicopter.On April 29, 2016, a CHC-operated Super Puma went down while carrying oil workers from the Gullfaks B platform to Bergen Airport.Iain Stuart, 41, from Laurencekirk, was among those killed in the crash off Turoy in Norway, taking place after the main rotor detached from the helicopter.
In the last seconds of its journey the chopper fell 2,000 feet, with witnesses describing an “explosion in the sky”.
The rotor broke off due to a “fatigue fracture” in a “second stage planet gear” in the main rotor gearbox.
Investigators later said it was probable that the failure was caused by tiny pieces of debris wearing away at the component. The system installed for detecting the particles was “inadequate”, they added.
Airbus
Manufacturer Airbus said it has always expressed “deep regret for the accident off Turoy” and in recent times has reached settlements with families of the victims, “while fully appreciating that such arrangements cannot possibly atone for the loss of their loved ones”.A spokesman said: “All of us were shocked and saddened by this event and we continue to extend our sincere and profound sympathies to the families of the bereaved.”
Despite the Super Puma crashes, though, many pilots still back the aircraft, which Airbus continues to sell widely in industries such as law enforcement and search and rescue.
Mr Molloy, of RMT, said, for whatever reason, the North Sea appears to have been its “Achilles heel”.
Along with Norwegian colleagues, trade unions in the UK plan to maintain a position that the Super Puma cannot fly again in the industry.
“I think you’d find a considerable pushback from the offshore workforce for that ever to be suggested in any case,” he said.
“Certainly this generation won’t be climbing into a Super Puma anytime soon.”
The victims were Iain Stuart, 41, Behnam Ahmadi, 54, Arild Fossedal, 43, Ole Magnar Kvamme, 60, Odd Geir Turøy, 54, Otto Mikal Vasstveit, 54, Kjetil Wathne, 51, Michele Vimercati, 44, Tommas Helland, 50, Espen Samuelsen, 35, Lyder Martin Telle, 57, and Olav Bastiansen, 57 and Silje Ye Rim Veivåg Krogsæther, 32.
It seems surprising that after 5 years there has not been a test to destruction of the gear box design involved.
Afaik, we have a plausible failure sequence, but no firm take away conclusions that would allow future designers to avoid a similar disater.
Can anyone shed light on the state of play in this area?
Afaik, we have a plausible failure sequence, but no firm take away conclusions that would allow future designers to avoid a similar disater.
Can anyone shed light on the state of play in this area?