Helicopter Height-Velocity (H-V) limitations
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Cat A Profiles - what now?
Hi Jim et al
Where does all this juggling with rules and regulations leave the poor old TRI/SFI trying to teach Cat A profiles that take the aircraft into the HV curve? Seems that the old 'get out' of saying that in these cases breaching the limitation is acceptable because the profile has been 'certified' is no longer available.
How am I supposed to deal with this anomalous and ambiguous puzzle?
G.
Where does all this juggling with rules and regulations leave the poor old TRI/SFI trying to teach Cat A profiles that take the aircraft into the HV curve? Seems that the old 'get out' of saying that in these cases breaching the limitation is acceptable because the profile has been 'certified' is no longer available.
How am I supposed to deal with this anomalous and ambiguous puzzle?
G.
Hi Geoff,
As shown in my previous post, the flight tests that establish the trajectory of the Category A procedure/profile demonstrate a safe path through the H-V Diagram.
(That also applies to the Category B take-off procedure contained in the RFM.)
The only point of debate (with Shawn) was if, and where, that is stated in the RFM.
Jim
As shown in my previous post, the flight tests that establish the trajectory of the Category A procedure/profile demonstrate a safe path through the H-V Diagram.
(9) Vertical takeoff and landing (VTOL) testing normally does not require separate HV testing. The takeoff and landing tests take on the combined characteristics of takeoff, landing, and HV tests.
The only point of debate (with Shawn) was if, and where, that is stated in the RFM.
Jim
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Take off and landing profiles
Jim
Does all this make it problematic when a large helicopter is used for 'Utility' work and has to operate from sites that cannot comply with either the published Cat A or Cat B profiles. Does EASA allow alleviations for 'aerial work'?
The one question that is always begged by these academic arguments and debates is that in the real world sites that are 'compliant' i.e. properly surveyed, are almost non existent and the very nature of most public transport (non airport) operations and all Cat B operations take place from unsurveyed (non-compliant) sites
Lest we forget offshore locations/vessels do not qualify as 'surveyed' in the 'obstacle' context by virtue of the changeable nature of their structures and environments.
G.
Does all this make it problematic when a large helicopter is used for 'Utility' work and has to operate from sites that cannot comply with either the published Cat A or Cat B profiles. Does EASA allow alleviations for 'aerial work'?
The one question that is always begged by these academic arguments and debates is that in the real world sites that are 'compliant' i.e. properly surveyed, are almost non existent and the very nature of most public transport (non airport) operations and all Cat B operations take place from unsurveyed (non-compliant) sites
Lest we forget offshore locations/vessels do not qualify as 'surveyed' in the 'obstacle' context by virtue of the changeable nature of their structures and environments.
G.
Hi Geoff,
This is a debate only about passenger transportation in Commercial Air Transport operating in accordance with Performance Class 2. The Performance Classes are not applicable to the ‘utility’ configuration or ‘Aerial Work’.
The larger helicopters configured in the ‘utility’ configuration (i.e. with less than 10 passenger seats) are appropriately addressed by Part 29. They are constrained only by the Category B mass which has to be provided as a limitation in accordance with Part 29.25 and mandated by Part 29.1519 (as is the Category A mass). There is no compulsion to use the Category B profile or be constrained by the H-V Diagram (the Category A and B H-V diagrams are almost always identical); any constraints on the operation will only be those contained in the regulations of the State (which is not part of this discussion).
Performance Class 2 was provided exactly for the Commercial Air Transport (off airport) operations that you have mentioned. It was adequately described in JAR-OPS 3 along with Exposure and the necessary alleviation from the H-V Diagram (which is a limitation for for Part 29 helicopters when: configured with 10 or more seats; or when certification in Category A is mandated under the operational regulations – as it is for Performance Class 2).
As explained in earlier posts, when transposed to EASA OPS the alleviation from the H-V Diagram, described above, was removed by the lawyers because EASA had ‘replaced’ the requirement to apply the RFM limitations from the operational regulations to paragraph 4.a of the Essential Requirement – so making it law.
The correct solutions (short term and long term) to this dilemma are contained in post #14 above.
Jim
This is a debate only about passenger transportation in Commercial Air Transport operating in accordance with Performance Class 2. The Performance Classes are not applicable to the ‘utility’ configuration or ‘Aerial Work’.
The larger helicopters configured in the ‘utility’ configuration (i.e. with less than 10 passenger seats) are appropriately addressed by Part 29. They are constrained only by the Category B mass which has to be provided as a limitation in accordance with Part 29.25 and mandated by Part 29.1519 (as is the Category A mass). There is no compulsion to use the Category B profile or be constrained by the H-V Diagram (the Category A and B H-V diagrams are almost always identical); any constraints on the operation will only be those contained in the regulations of the State (which is not part of this discussion).
Performance Class 2 was provided exactly for the Commercial Air Transport (off airport) operations that you have mentioned. It was adequately described in JAR-OPS 3 along with Exposure and the necessary alleviation from the H-V Diagram (which is a limitation for for Part 29 helicopters when: configured with 10 or more seats; or when certification in Category A is mandated under the operational regulations – as it is for Performance Class 2).
As explained in earlier posts, when transposed to EASA OPS the alleviation from the H-V Diagram, described above, was removed by the lawyers because EASA had ‘replaced’ the requirement to apply the RFM limitations from the operational regulations to paragraph 4.a of the Essential Requirement – so making it law.
The correct solutions (short term and long term) to this dilemma are contained in post #14 above.
Jim
Last edited by JimL; 15th Aug 2014 at 11:20.
General
In order to understand how NPRM 80-25 effected the certification of Category A and Category B rotorcraft, it is necessary to examine what changed and why. There were two substantial changes: one concerned the applicability of the H-V Diagram as a Limitation; and another the certification and operating criteria with respect to mass and numbers of passengers carried.
In addition the upper limit of 20,000lbs, for permitting the Operating Limitations of Category B, was removed.
Changes that Affected the Requirements for the H-V Diagram
The substantial change to Part 29.1 was made effective in 1983; before that time, although multi-engine rotorcraft could be certificated in Category A and/or Category B, they both had to have the H-V Diagram as a Limitation.
In NPRM 80-25 a number of changes were made to ensure that, whilst Category B no longer required the H-V Diagram as a Limitation, it was still required for the definition of the Category B take-off and landing WAT limit conditions. The necessary changes were made (in this amendment and subsequent ones) to partition the requirements such that all cases were covered .
The following amendments were made:
* Evidenced in the ESF awarded to the AW189 by EASA.
It is understood that in all cases, 29.87 has to be complied with – in addition:
In order to understand how NPRM 80-25 effected the certification of Category A and Category B rotorcraft, it is necessary to examine what changed and why. There were two substantial changes: one concerned the applicability of the H-V Diagram as a Limitation; and another the certification and operating criteria with respect to mass and numbers of passengers carried.
In addition the upper limit of 20,000lbs, for permitting the Operating Limitations of Category B, was removed.
Changes that Affected the Requirements for the H-V Diagram
The substantial change to Part 29.1 was made effective in 1983; before that time, although multi-engine rotorcraft could be certificated in Category A and/or Category B, they both had to have the H-V Diagram as a Limitation.
In NPRM 80-25 a number of changes were made to ensure that, whilst Category B no longer required the H-V Diagram as a Limitation, it was still required for the definition of the Category B take-off and landing WAT limit conditions. The necessary changes were made (in this amendment and subsequent ones) to partition the requirements such that all cases were covered .
The following amendments were made:
• 29.1 ‘Applicability’ – to establish when the H-V Diagram, as a limitation, was necessary .
• 29.79 (eventually moved to 29.87 and the title changed from ‘Limiting height-speed envelope’ to ‘Height velocity envelope’) - as a single requirement, the establishment of an H-V Diagram;
• 29.1517 ‘Limiting height-speed envelope’ - to ensure that it contained a requirement only for Category A rotorcraft;
• 29.1587 ‘Performance Information’ – adding clause (b)(6) to require the H-V Diagram as Performance Information for Category B (because of changes to 29.1517);
• 29.1583(f) ‘Operating Limitations’ – remained unchanged because it (only) pointed to 29.1517.
In spite of the intent being made quite clear in NPRM 80-25, there is still confusion, in some certificating authorities*, as to when one or both of the requirements (information and/or limitation) have to be met.• 29.79 (eventually moved to 29.87 and the title changed from ‘Limiting height-speed envelope’ to ‘Height velocity envelope’) - as a single requirement, the establishment of an H-V Diagram;
• 29.1517 ‘Limiting height-speed envelope’ - to ensure that it contained a requirement only for Category A rotorcraft;
• 29.1587 ‘Performance Information’ – adding clause (b)(6) to require the H-V Diagram as Performance Information for Category B (because of changes to 29.1517);
• 29.1583(f) ‘Operating Limitations’ – remained unchanged because it (only) pointed to 29.1517.
* Evidenced in the ESF awarded to the AW189 by EASA.
It is understood that in all cases, 29.87 has to be complied with – in addition:
• When a rotorcraft is certificated in Category B – compliance has to be shown with 29.1587(b)(6);
• When a rotorcraft is certificated in Category A:
• When a rotorcraft is certificated under 29.1(e) – compliance has to be shown with 29.1517 and 29.1583(f);
• When a rotorcraft is certificated in under 29.1(e) and 29.1(f) – compliance has to be shown with 29.1517 and 29.1583(f) but 29.1587(b)(6) is optional.
The requirement of the H-V Diagram as a Limitation is bound to two imperatives: • When a rotorcraft is certificated in Category A:
• compliance has to be shown with 29.1517 and 29.1583(f); or
• if the Category A procedures are mandated, 29.1583(f) is deemed to have been satisfied. However the Category A procedures have either to be contained in the Limitations Section or referenced in the Limitations Sections as being mandatory requirements;
• When a rotorcraft is certificated in Category A and B – compliance has to be shown with 29.1517 and 29.1583(f) but 29.1587(b)(6) is optional;• if the Category A procedures are mandated, 29.1583(f) is deemed to have been satisfied. However the Category A procedures have either to be contained in the Limitations Section or referenced in the Limitations Sections as being mandatory requirements;
• When a rotorcraft is certificated under 29.1(e) – compliance has to be shown with 29.1517 and 29.1583(f);
• When a rotorcraft is certificated in under 29.1(e) and 29.1(f) – compliance has to be shown with 29.1517 and 29.1583(f) but 29.1587(b)(6) is optional.
1. when a rotorcraft is configured with 10 or more seats; and/or
2. when a rotorcraft is certificated in Category A under CS-29.
Jim
2. when a rotorcraft is certificated in Category A under CS-29.
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Cut to the quick Jim....
.... and tell us what the impact of this debacle is likely to be on the community of fine upstanding helo operators whose only aim in life is to make a crust whilst staying within the law?
G
G
Hi Geoff,
None whatsoever if the status quo ante is preserved.
Let me explain why this thread is being kept alive: the harmony between certification and operations (Part 29, FAR 91 and JAR-OPS 3) provides a balance, on the H-V issue, which has endured – for FARs since 1983 (the significant amendment of Part-29) and for JAR-OPS 3 since 1998. It is in the best interest of the industry that FAA and EASA maintain a harmonised Part 29.
This balance was potentially put in jeopardy with the provision of EASA Essential Requirements which placed compliance with the RFM Limitations in Law rather than Regulations. As previously explained, this was noted when JAR-OPS 3 was transposed to EASA OPS because it invalidated the ‘partial and controlled’ alleviation from the H-V Limitation (the alleviation was removed, by lawyers, from the draft EASA OPS).
Removal of the alleviation invalidated Exposure in offshore operations (CAT) because it was placed outside the ‘Law’. The best solution is a continuation of the status quo as outlined in post #14; a tried and tested solution which preserved harmonisation in Part 29 (FAR 29 and CS-29).
During the time that the EASA working group were considering solutions, AW applied for, and were granted, an EASA Equivalent Safety Finding (ESF) on the requirement to provide an H-V Diagram; this finding was not in compliance with the ‘rules’ - as shown in the post above (the AW 189 is certificated as a ‘Large Rotorcraft Category A and B’). The proposed ESF was commented to that effect but, in EASA’s response, a lack of knowledge/understanding of both the certification and operational requirements was shown.
Although proposals and CRD documents are published, the readers are far fewer than those on PPRune. PPRune is read extensively in the industry (including regulators); in the absence of access to discussion on these matters, PPRune provides the only opportunity to offer an explanation of the regulations and, more importantly, their intent.
It is only with this knowledge that an appropriate solution will be put into place.
Jim
None whatsoever if the status quo ante is preserved.
Let me explain why this thread is being kept alive: the harmony between certification and operations (Part 29, FAR 91 and JAR-OPS 3) provides a balance, on the H-V issue, which has endured – for FARs since 1983 (the significant amendment of Part-29) and for JAR-OPS 3 since 1998. It is in the best interest of the industry that FAA and EASA maintain a harmonised Part 29.
This balance was potentially put in jeopardy with the provision of EASA Essential Requirements which placed compliance with the RFM Limitations in Law rather than Regulations. As previously explained, this was noted when JAR-OPS 3 was transposed to EASA OPS because it invalidated the ‘partial and controlled’ alleviation from the H-V Limitation (the alleviation was removed, by lawyers, from the draft EASA OPS).
Removal of the alleviation invalidated Exposure in offshore operations (CAT) because it was placed outside the ‘Law’. The best solution is a continuation of the status quo as outlined in post #14; a tried and tested solution which preserved harmonisation in Part 29 (FAR 29 and CS-29).
During the time that the EASA working group were considering solutions, AW applied for, and were granted, an EASA Equivalent Safety Finding (ESF) on the requirement to provide an H-V Diagram; this finding was not in compliance with the ‘rules’ - as shown in the post above (the AW 189 is certificated as a ‘Large Rotorcraft Category A and B’). The proposed ESF was commented to that effect but, in EASA’s response, a lack of knowledge/understanding of both the certification and operational requirements was shown.
Although proposals and CRD documents are published, the readers are far fewer than those on PPRune. PPRune is read extensively in the industry (including regulators); in the absence of access to discussion on these matters, PPRune provides the only opportunity to offer an explanation of the regulations and, more importantly, their intent.
It is only with this knowledge that an appropriate solution will be put into place.
Jim
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During the time that the EASA working group were considering solutions, AW applied for, and were granted, an EASA Equivalent Safety Finding (ESF) on the requirement to provide an H-V Diagram; this finding was not in compliance with the ‘rules’ - as shown in the post above (the AW 189 is certificated as a ‘Large Rotorcraft Category A and B’). The proposed ESF was commented to that effect but, in EASA’s response, a lack of knowledge/understanding of both the certification and operational requirements was shown.
EASA AW189 certification team has proved great competence and vision on this subject, unfortunately the H-V NPA working group has missed it completely.
The ELOS was only addressed to the different way of presenting the H-V envelope information and NOT whether to provide it or not provided it, in fact all H-V information is included in the AW189 RFM.
I want to clear some concepts that EASA Cert team has made very clear and agreed with AW proposal.
The H-V limitations applies to takeoff and landing profiles and HOGE conditions for Cat B certification and only for takeoff and landings profiles for Cat A.
Being (by rule) the H-V envelope/limitation only applicable to the type of surface where it has been demonstrated (that in all RFM is hard/runway type surface) this limitation can only be considered applicable to the published takeoff and landing procedures that are the only conditions where the H-V has been demonstrated.
Based on this it was considered compliant, considering the applicable CS29 rules, that H-V limitation was demonstrated.
AW has considered that the inclusion of the actual traditional H-V chart that was fully demonstrated as per the required rules, was of low operational values. AW proposed instead to provide what AW considered a much more valuable information that can be faced in real operations where "usually" very rarely a Cat B takeoff/landing profile takes place over a runway and all HOGE operations almost never occur over it. It was then considered to introduce in the performance section a fully comprehensive set of charts that provide Safe Vertical Rejects and Fly-Away performance WAT charts with an actual height loss data including wind/speed contribution. We wanted to tell the pilot what he can do to save the helicopter and not what he cannot do without telling what is a safe escape.
This was also corroborated by the fact that the traditional H-V information is only limited to one type of surface and therefore not applicable to any other operational surface.
For Cat A procedures, the WAT charts included in the limitations section have been demonstrated to be cleared of any H-V limitation.
I want to reiterate my thanks again the EASA Cert team for their collaboration in achieving a step forward towards a new vision in providing a better and more operational oriented RFM for these class of helicopters.
One more consideration: there are no H-V envelopes for helideck sites, it is impossible to comply with these rules for these surfaces, therefore there are no possible infringements of the H-V limitation. Even a takeoff profile that complies with the published H-V limitation, if carried out from an helideck, can be fatal.
The only safe way to operate from helidecks is to apply procedures with zero exposures, i.e. PC1.
Thanks Dino,
In order to provide a cogent response, it is necessary to unpick some of the elements of your post for discussion.
A Common Certification code
Part 29 (FAR 29 and CS-29) represents a harmonised certification code in the Western World. The acceptance of Type Certification among those States who use this code, depends upon a common view of what the code represents. Guidance is provided in a single advisory circular which, for historical reasons, has an FAA bias (reference to operational rules is primarily oriented towards the FARs). Where this guidance is not seen as sufficiently comprehensive, some States have chosen to provide additional material on methods of compliance (this uses the statement in AC 29.2C that it represents a method but not the only one).
Operational Rules
Operational rules are not harmonised (although ICAO does provide a common Standard); for some States, the certification code underpins the operational rules; for others, it can represent an unnecessary constraint on operational practices based upon risk management. The H-V Diagram represents one such case; in States without a performance code, it provides a moderating mechanism; in States with a performance code in compliance with ICAO, it constrains under circumstances where risk assessment permits finer control.
The H-V Diagram as a Limitation
The H-V Limitation is a clumsy device and, even in those States where it is required to underpin control of operations, it represents a barrier to some legitimate operations (offshore for example). For that reason, all States need a method of alleviation in these cases.
States with a performance code in compliance with ICAO do not require the H-V Diagram as a Limitation and, in the past, have moved to have it only as information. That this move is resisted is understood because the required changes to the operational code in some States would be seen as seismic by some stake holders. For that reason, FAR 29 has remain unchanged and control has been provided by alleviation in Regulations. This method is pragmatic because it retains a common view on the application of Part 29 whilst allowing flexibility in operations.
The Conditions of an H-V Diagram
The H-V Diagram defines an envelope of airspeed and height above the ground from which a safe power-off or OEI landing cannot be made. The flight manual should list any procedures which may apply to specific points (e.g. high speed points) and test conditions, such as runways surface etc.
The surface condition has relevance to the H-V Diagram only inasmuch as it represents a further limiting condition – i.e. a landing is not guaranteed in the case of an engine failure outside the H-V avoid curve if the surface conditions do not permit it. In ICAO, this additional factor is included in the definition of a safe-forced-landing – which consists of two elements:
Requirements for Provision of the H-V Diagram (see post #24)
The requirement for provision of the H-V Diagram is represented in two rules: 29.1583 ‘Operating Limitation’, and 29.1587 ‘Performance Information’ – both have to be satisfied.
29.1583(f) points to 29.1517 which requires, for Category A rotorcraft, a Limiting height speed envelope to be established; this requirement can be set aside only if the Category A procedures are mandated. If they are mandated they have to be contained in the Limitations Section or referred to in the Limitation Section. To my knowledge, that is not the case with the AW189. If that were the case, all flights would have to be flown within the Category A procedures – including those offshore.
29.1587(b)(6) requires, for Category B rotorcraft, the provision of a height-speed envelope. The exception to this is if one is provided as an operating limitation – i.e. in compliance with 29.1583(f). If Category A procedures are mandated, then it is necessary.
Must a Rotorcraft that is Certificated in Category A Apply the Category A Procedures?
Whilst the WAT for each of the Category A procedures represents a limitation for that procedure, it is difficult to see how that represents a general requirement for all flights to be conducted in accordance with Category A procedures – including flights to helidecks. That is not a result with which the operating community would be happy.
Are Category A procedures mandatory?
Let us examine the rules/guidance - we start with the definition of Category A:
The strongest signal is provided in the guidance in AC 29.1583(b)(8)(i) with respect to the relationship between the Category A procedures and the H-V Diagram as a Limitations:
It is therefore concluded that certification in Category A does not imply that the Category A procedures have to be used!
Jim
In order to provide a cogent response, it is necessary to unpick some of the elements of your post for discussion.
A Common Certification code
Part 29 (FAR 29 and CS-29) represents a harmonised certification code in the Western World. The acceptance of Type Certification among those States who use this code, depends upon a common view of what the code represents. Guidance is provided in a single advisory circular which, for historical reasons, has an FAA bias (reference to operational rules is primarily oriented towards the FARs). Where this guidance is not seen as sufficiently comprehensive, some States have chosen to provide additional material on methods of compliance (this uses the statement in AC 29.2C that it represents a method but not the only one).
Operational Rules
Operational rules are not harmonised (although ICAO does provide a common Standard); for some States, the certification code underpins the operational rules; for others, it can represent an unnecessary constraint on operational practices based upon risk management. The H-V Diagram represents one such case; in States without a performance code, it provides a moderating mechanism; in States with a performance code in compliance with ICAO, it constrains under circumstances where risk assessment permits finer control.
The H-V Diagram as a Limitation
The H-V Limitation is a clumsy device and, even in those States where it is required to underpin control of operations, it represents a barrier to some legitimate operations (offshore for example). For that reason, all States need a method of alleviation in these cases.
States with a performance code in compliance with ICAO do not require the H-V Diagram as a Limitation and, in the past, have moved to have it only as information. That this move is resisted is understood because the required changes to the operational code in some States would be seen as seismic by some stake holders. For that reason, FAR 29 has remain unchanged and control has been provided by alleviation in Regulations. This method is pragmatic because it retains a common view on the application of Part 29 whilst allowing flexibility in operations.
The Conditions of an H-V Diagram
The H-V Diagram defines an envelope of airspeed and height above the ground from which a safe power-off or OEI landing cannot be made. The flight manual should list any procedures which may apply to specific points (e.g. high speed points) and test conditions, such as runways surface etc.
The surface condition has relevance to the H-V Diagram only inasmuch as it represents a further limiting condition – i.e. a landing is not guaranteed in the case of an engine failure outside the H-V avoid curve if the surface conditions do not permit it. In ICAO, this additional factor is included in the definition of a safe-forced-landing – which consists of two elements:
the rate of closure with the surface following an engine failure; and,
the conditions of the surface on which a touchdown is made
Only the former is a condition of the H-V Diagram. Surface conditions are non-sequitur and have no place in the determination of compliance.the conditions of the surface on which a touchdown is made
Requirements for Provision of the H-V Diagram (see post #24)
The requirement for provision of the H-V Diagram is represented in two rules: 29.1583 ‘Operating Limitation’, and 29.1587 ‘Performance Information’ – both have to be satisfied.
29.1583(f) points to 29.1517 which requires, for Category A rotorcraft, a Limiting height speed envelope to be established; this requirement can be set aside only if the Category A procedures are mandated. If they are mandated they have to be contained in the Limitations Section or referred to in the Limitation Section. To my knowledge, that is not the case with the AW189. If that were the case, all flights would have to be flown within the Category A procedures – including those offshore.
29.1587(b)(6) requires, for Category B rotorcraft, the provision of a height-speed envelope. The exception to this is if one is provided as an operating limitation – i.e. in compliance with 29.1583(f). If Category A procedures are mandated, then it is necessary.
Must a Rotorcraft that is Certificated in Category A Apply the Category A Procedures?
Whilst the WAT for each of the Category A procedures represents a limitation for that procedure, it is difficult to see how that represents a general requirement for all flights to be conducted in accordance with Category A procedures – including flights to helidecks. That is not a result with which the operating community would be happy.
Are Category A procedures mandatory?
Let us examine the rules/guidance - we start with the definition of Category A:
‘category A with respect to helicopters’ means a multi-engined helicopter designed with engine and system isolation features specified in the applicable airworthiness codes and capable of operations using take-off and landing data scheduled under a critical engine failure concept that assures adequate designated surface area and adequate performance capability for continued safe flight or safe rejected take-off in the event of engine failure;
Because this (JAA) definition was provided after the Performance Classes were defined in ICAO and JAR-OPS 3, it is likely that the wording was deliberate. Capability does not imply an imperative, or compulsion, to use the Category A procedures.The strongest signal is provided in the guidance in AC 29.1583(b)(8)(i) with respect to the relationship between the Category A procedures and the H-V Diagram as a Limitations:
Therefore, if the Category A takeoff and landing profiles, procedures, and WAT limitations are adequately and clearly defined in the RFM, this information is considered sufficient for compliance with the requirements of § 29.1583(f) without the inclusion of an actual HV diagram.
The Category A procedures and profile definitions may be presented in the normal procedures or performance sections of the RFM but should be referenced as being mandatory requirements in the limitations section unless an HV diagram valid for Category A operations is presented.
There can be no misunderstanding of the intent of this passage; unless the Category A procedures are mandated, an H-V Diagram is required in the Limitations section. Ipso facto, if the H-V Diagram is in the Limitations section, the Category A procedures are not mandated (unless so specified in the Operational Regulations).The Category A procedures and profile definitions may be presented in the normal procedures or performance sections of the RFM but should be referenced as being mandatory requirements in the limitations section unless an HV diagram valid for Category A operations is presented.
It is therefore concluded that certification in Category A does not imply that the Category A procedures have to be used!
Jim
Last edited by JimL; 10th Sep 2014 at 07:38. Reason: Editorial
JimL,
''The H-V Diagram defines an envelope of airspeed and height above the ground from which a safe power-off or OEI landing cannot be made."
I have read somewhere:
" ... or OEI landing is not guaranteed by the OEM."
Cheers
''The H-V Diagram defines an envelope of airspeed and height above the ground from which a safe power-off or OEI landing cannot be made."
I have read somewhere:
" ... or OEI landing is not guaranteed by the OEM."
Cheers
Thanks ATN. The text was taken verbatim from AC 29.79.
In some sense your additional text illustrates one of the problems. Category A and B procedures are provided in a strict test environment; the OEM has no knowledge over and on which surfaces, operations are performed. That is left to the operational regulations.
Jim
In some sense your additional text illustrates one of the problems. Category A and B procedures are provided in a strict test environment; the OEM has no knowledge over and on which surfaces, operations are performed. That is left to the operational regulations.
Jim
The rationale and intent of Part 29.1 and its attendant clauses has now been explained – hopefully, so all can understand the implication of the H-V Diagram in both of its forms as a Limitation and Information. Leaving aside the issue of the AW189, which appears to mandate the Category A procedures; it should not be inferred from my comments that the H-V Diagram as a Limitation is supported – it is not.
When NPA 2014-19 was published, comments had to be with EASA by the 27th October 2014 – which was one day ahead of the opt-out period for Air OPS (28th October 2014). As was indicated in the covering letter to States, there will be a bridging period between the end of the opt-out period and adoption of the amended rules.
The comment period has now been extended to 27th November 2014 and so the first priority of States becomes the necessity to address the impending (28th October 2014) problem of the ‘illegal’ penetration of the H-V Diagram for rotorcraft that have been certificated in Category A under CS-29 – i.e. most helicopters used in North Sea offshore operations.
Member States were advised that, in order to continue operations in accordance with the status quo (Performance Class 2 with Exposure), it would be necessary for each to grant an exception under Article 14(4) of the Basic Regulation.
The regulation goes on to explain that the agency shall assess whether the exemptions are less restrictive than the Community provisions. As a correctly constructed exemption is intended to preserve the status quo ante, it is unlikely that it would be questioned by the Community (or EASA as its agent).
In considering what this exemption might be, it is necessary to look for the key element that has resulted in this situation. It is Article 8(1) of the Basic Regulation:
Requiring compliance with Essential Requirement 4(a) of Annex IV:
In order to permit continued operations to the current safety level, a 14(4) exemption must therefore provide alleviation from Article 8(1) in respect of compliance with Essential Requirement 4(a) of Annex IV of that regulation.
The conditions of the exemption should be those which were extant in JAR-OPS 3 – as transposed to Air OPS. That is:
Jim
When NPA 2014-19 was published, comments had to be with EASA by the 27th October 2014 – which was one day ahead of the opt-out period for Air OPS (28th October 2014). As was indicated in the covering letter to States, there will be a bridging period between the end of the opt-out period and adoption of the amended rules.
The comment period has now been extended to 27th November 2014 and so the first priority of States becomes the necessity to address the impending (28th October 2014) problem of the ‘illegal’ penetration of the H-V Diagram for rotorcraft that have been certificated in Category A under CS-29 – i.e. most helicopters used in North Sea offshore operations.
Member States were advised that, in order to continue operations in accordance with the status quo (Performance Class 2 with Exposure), it would be necessary for each to grant an exception under Article 14(4) of the Basic Regulation.
“4. Member States may grant exemptions from the substantive requirements laid down in this Regulation and its implementing rules in the event of unforeseen urgent operational circumstances or operational needs of a limited duration, provided the level of safety is not adversely affected. The Agency, the Commission and the other Member States shall be notified of any such exemptions as soon as they become repetitive or where they are granted for periods of more than two months.”
In considering what this exemption might be, it is necessary to look for the key element that has resulted in this situation. It is Article 8(1) of the Basic Regulation:
“1. The operation of aircraft referred to in Article 4(1)(b) and (c) shall comply with the essential requirements set out in Annex IV and, if applicable, Annex Vb.”
“4.a An aircraft must be operated in accordance with its airworthiness documentation and all related operating procedures and limitations as expressed in its approved flight manual or equivalent documentation, as the case may be. The flight manual or equivalent documentation must be available to the crew and kept up to date for each aircraft.”
The conditions of the exemption should be those which were extant in JAR-OPS 3 – as transposed to Air OPS. That is:
“For helicopters certificated as Category A rotorcraft under CS-29, a momentary flight through the height velocity (H-V) envelope is permitted during take-off and landing phases when operating in accordance with any of the following requirements:
For operations in CAT.POL.H.420 – helicopter operations over a hostile environment located outside a congested area; no exemption is required because the limit of the number of passengers is six (and therefore could make use of the 9 seat Supplement – under Performance Class 3 either Category A or Category B certification is permitted): SPA.HEMS.125 – performance requirements for HEMS operations; also does not require an exemption because it operates under CAT.POL.H.305, which will, itself, be exempted.CAT.POL.H.305 – operations without an assured safe forced landing capability;
CAT.POL.H.225 – helicopter operations to/from a public interest site.”
CAT.POL.H.225 – helicopter operations to/from a public interest site.”
Jim
Last edited by JimL; 10th Sep 2014 at 08:14. Reason: Grammar
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Tell us about the AW189 situation Jim...
So are we saying that the net effects of the new rule structure are that all 189 operations must be Cat A compliant, even offshore?
If that is so, and given that we have often pointed out the impossibility of meeting Cat A performance requirements in the offshore environment due to the deterministic nature of the regulation and the difficulties with the obstacle environment, then we have a bit of a quandary to solve.
On the one hand it appears we have to comply with Cat A Procedures but we can't because they require us to predict (prior to departure from land) a level of obstacle clearance at the offshore location that we are unable to provide due to the unquantifiable interactions of wind, turbulence and the dynamic nature of offshore obstructions.(moveable derricks, supply boats, crane/lay/work over barges, fitful winds and turbine exhaust pollution).
G.
If that is so, and given that we have often pointed out the impossibility of meeting Cat A performance requirements in the offshore environment due to the deterministic nature of the regulation and the difficulties with the obstacle environment, then we have a bit of a quandary to solve.
On the one hand it appears we have to comply with Cat A Procedures but we can't because they require us to predict (prior to departure from land) a level of obstacle clearance at the offshore location that we are unable to provide due to the unquantifiable interactions of wind, turbulence and the dynamic nature of offshore obstructions.(moveable derricks, supply boats, crane/lay/work over barges, fitful winds and turbine exhaust pollution).
G.
This perhaps this should have gone onto the AW189 thread because the issue does not result from the NPA proposal but from the interpretation of the regulation/guidance that has been shown above. It does, however, reveal an interpretation of the use of Category A procedures that permeates NPA 2014-19 and, for that reason, here is as good a place as any to provide an explanation.
The configuration of the AW189 RFM is as a consequence of the Equivalent Safety Finding (ESF), or more accurately, from the interpretation that has been put on CS-29 by EASA and AW. In the ESF there is an implicit assumption by the author/respondent that certification in Category A requires Category A procedures to be used (which, as was explained above, is not correct).
The ESF against CS 29.1587(b)(6) was intended to permit AW to replace the H-V Diagram in the Performance Section of the RFM with two other graphs, ‘reject’ and ‘fly-away’. My comment on the AW189 thread with respect to this was; in principle, it was supported but, because the ‘reject’ graph did not extend to 8,300kg, it did not completely fulfil the function of the H-V Diagram. The requirement of the contents of an H-V diagram are specific:
The maximum Category A mass is 8,300kg, ipso facto the requirement is not completely satisfied by the ‘reject’ graph (although it, along with the ‘fly-away’ graph is welcome in assisting in the provision of Performance Class 2 profiles).
What the ESF did not do was to make a determination against the requirement of CS 29.1583(f) - to provide an H-V Diagram in the Limitations Section of the RFM. The two requirements are not synonymous (the H-V Diagrams are, of course, identical); although the provision of an H-V Diagram in the Limitations Section can be regarded as satisfying the requirement for one in the Performance Section, the opposite is not true.
For a Category A helicopter, there must be an H-V Diagram in the Limitations Section unless the Category A procedures are mandated. As far as I am aware, there is no H-V Diagram in the Limitation Section of the AW189 so, the assumption we must make is that Category A procedures are mandated.
Contrary to what Dino has said, in EASA there is a lack of understanding of the application of Category A to Operational Requirements and, it would appear, a lack of understanding of their own certification regulations and guidance with respect to the provision of the H-V Diagram.
The NPA totally ignores the principle of Part 29.1 that, if there are 10 or more seats, the helicopter must be certificated in Category A and apply the Category A Limitations (i.e. for Passenger Transportation). Additionally, if the helicopter is operated in Performance Class 2, it must be certificated in Category A (with all of the concomitant limitations). The FAA and JAA understood this and provided, in their operational regulations, an alleviation from the H-V Diagram under limited and controlled conditions (in the JAA, this applied only under an Approval for Exposure).
Mandating of Category A procedures is not welcomed because, as you have so correctly stated, they are not always possible (to comply with) in the offshore environment.
The configuration of the AW189 RFM is as a consequence of the Equivalent Safety Finding (ESF), or more accurately, from the interpretation that has been put on CS-29 by EASA and AW. In the ESF there is an implicit assumption by the author/respondent that certification in Category A requires Category A procedures to be used (which, as was explained above, is not correct).
The ESF against CS 29.1587(b)(6) was intended to permit AW to replace the H-V Diagram in the Performance Section of the RFM with two other graphs, ‘reject’ and ‘fly-away’. My comment on the AW189 thread with respect to this was; in principle, it was supported but, because the ‘reject’ graph did not extend to 8,300kg, it did not completely fulfil the function of the H-V Diagram. The requirement of the contents of an H-V diagram are specific:
CS 29.87 Height-velocity envelope
(a) If there is any combination of height and forward velocity (including hover) under which a safe landing cannot be made after failure of the critical engine and with the remaining engines (where applicable) operating within approved limits, a height velocity envelope must be established for:
(a) If there is any combination of height and forward velocity (including hover) under which a safe landing cannot be made after failure of the critical engine and with the remaining engines (where applicable) operating within approved limits, a height velocity envelope must be established for:
(1) All combinations of pressure altitude and ambient temperature for which takeoff and landing are approved; and
(2) Weight, from the maximum weight (at sea level) to the highest weight approved for takeoff and landing at each altitude. For helicopters, this weight need not exceed the highest weight allowing hovering out of ground effect at each altitude.
(b) For single engine or multiengine rotorcraft that do not meet the Category A engine isolation requirements, the height velocity envelope for complete power failure must be established.
(2) Weight, from the maximum weight (at sea level) to the highest weight approved for takeoff and landing at each altitude. For helicopters, this weight need not exceed the highest weight allowing hovering out of ground effect at each altitude.
What the ESF did not do was to make a determination against the requirement of CS 29.1583(f) - to provide an H-V Diagram in the Limitations Section of the RFM. The two requirements are not synonymous (the H-V Diagrams are, of course, identical); although the provision of an H-V Diagram in the Limitations Section can be regarded as satisfying the requirement for one in the Performance Section, the opposite is not true.
For a Category A helicopter, there must be an H-V Diagram in the Limitations Section unless the Category A procedures are mandated. As far as I am aware, there is no H-V Diagram in the Limitation Section of the AW189 so, the assumption we must make is that Category A procedures are mandated.
Contrary to what Dino has said, in EASA there is a lack of understanding of the application of Category A to Operational Requirements and, it would appear, a lack of understanding of their own certification regulations and guidance with respect to the provision of the H-V Diagram.
The NPA totally ignores the principle of Part 29.1 that, if there are 10 or more seats, the helicopter must be certificated in Category A and apply the Category A Limitations (i.e. for Passenger Transportation). Additionally, if the helicopter is operated in Performance Class 2, it must be certificated in Category A (with all of the concomitant limitations). The FAA and JAA understood this and provided, in their operational regulations, an alleviation from the H-V Diagram under limited and controlled conditions (in the JAA, this applied only under an Approval for Exposure).
Mandating of Category A procedures is not welcomed because, as you have so correctly stated, they are not always possible (to comply with) in the offshore environment.
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This is the problem with looking for absolutes in a world were very few exist. The HV curve is a great example - its a fundamentally inadequate piece of information for the environment where most helicopters operate (off airport).
It would appear there has been a problem created where none existed. Much effort will go into fixing it and everyone will congratulate themselves on a job well done when a solution is agreed. The end result is a zero sum outcome that achieves nothing but confusion and uncertainty for those who have to operate these things in the meantime.
With the reliability of modern turbines, the HV chart should only be guidance material, particularly for multi engine aircraft. Our regulations and regulators (and to some degree industry) are still focused on yesterdays problems... trying to shoehorn rapidly evolving operations and aircraft into a 1970's regulatory environment and mindset. I like AW's preemptive action on this for the 189 and hope that others will follow.
It would appear there has been a problem created where none existed. Much effort will go into fixing it and everyone will congratulate themselves on a job well done when a solution is agreed. The end result is a zero sum outcome that achieves nothing but confusion and uncertainty for those who have to operate these things in the meantime.
With the reliability of modern turbines, the HV chart should only be guidance material, particularly for multi engine aircraft. Our regulations and regulators (and to some degree industry) are still focused on yesterdays problems... trying to shoehorn rapidly evolving operations and aircraft into a 1970's regulatory environment and mindset. I like AW's preemptive action on this for the 189 and hope that others will follow.
For States which have a Performance Code in compliance with ICAO Annex 6, regulation of performance is achieved with use of the ‘Performance Classes’ and by controlling limited exposure (outside these classes) with risk assessed procedures which include a safety target, mitigating conditions and limits on passenger numbers. For these States, the retention of the H-V Diagram as a Limitation in Part 29 is an unnecessary constraint on operations.
For helicopters employed in offshore operations, most offshore take-off and landings penetrate the (traditionally presented) H-V avoid curve – this represents more than 50% of all take-off and landings ever performed with these helicopters. The probability of an engine failure leading to a catastrophic event for offshore take-off or landing with exposure is about 5 x 10-8 (1:20,000,000) - for operations outside of a Category A or Category B procedure.
Not all States using Part 29 have a Performance Code; those which do not, rely upon the ‘conditioning’ clauses of Part 29.1, and retention of the H-V Diagram as a Limitation, to provide (operational) control of performance within the flight manual. This results in a situation where States rely upon alleviation from the Limitation of the H-V Diagram when operating offshore with more than nine passenger seats.
In the modern era, all helicopters operating offshore in Europe are certificated in Category A and B – i.e. they all comply with the Category A ‘build’ standard. Dual qualification permits these helicopters to be employed in ‘utility operations’ (aerial work) as well as ‘passenger transportation’ (commercial air transport – offshore and onshore).
All Category A and B procedures (from Subpart B ‘Flight’ of Part 29) ensure that the helicopter can tolerate an engine failure on take-off or landing: for Category A, by providing profiles that have demonstrated engine-failure accountability; and, for Category B, by mandating take-off and landing profiles that remain clear of the H-V avoid curve.
All dual qualified helicopters have a ‘capability’ (as expressed in the EASA definition of Category A) of using the Category A or Category B procedures; helicopters cannot be ‘operated’ in Category A or Category B they have to be ‘operated’ in accordance with the Performance Classes (or with exposure) – i.e. it is the performance code that determines which Performance Class has to be employed. Certification in Category A does not mandate the use of the Category A procedures.
The significant intent of the changes to Part 29.1 as a result of NPRM 80-25, was to remove the H-V Diagram as a Limitation for ‘utility operations’ (aerial work) and, for simplicity, to bind that to a seating configuration of less than 10. Offshore operations (or any Commercial Air Transport) should not be regarded as ‘utility operations’; for that reason, more sophisticated methods of regulation need to be employed.
The one inescapable fact that results from Part 29.1 is that unless Category A procedures are mandated, the H-V Diagram is a Limitation when more than nine passengers are carried.
In NPA 2014-19; the proposed amendment to CS-29 – particularly in operations with more than nine passengers – is legally questionable, undermines the logic and intent of Part 29.1, and introduces doubt and unnecessary complication into the certification process; in order to preserve a world-wide harmonised code, it should not be undertaken. The introduction of Category B to Performance Class 2 requirements adds complications to the code under circumstances where the sole intent is to avoid the H-V Limitation (i.e. to circumvent CS-29.1 and CS-29.1517).
In the short term; a much simpler/better method would be to preserve the status quo (in Europe and world-wide) by: prepending an enabling clause into Subparagraph 4.a of the essential requirements; and, by adding an alleviating clause into CAT.POL.H.305. The decision not to proceed with this option should be revisited, or justification - acceptable to interested parties - provided.
In the long term; there is need for discussions between the Certificating Authorities about the removal of the H-V Diagram as a Limitation from Part 29.
Jim
For helicopters employed in offshore operations, most offshore take-off and landings penetrate the (traditionally presented) H-V avoid curve – this represents more than 50% of all take-off and landings ever performed with these helicopters. The probability of an engine failure leading to a catastrophic event for offshore take-off or landing with exposure is about 5 x 10-8 (1:20,000,000) - for operations outside of a Category A or Category B procedure.
Not all States using Part 29 have a Performance Code; those which do not, rely upon the ‘conditioning’ clauses of Part 29.1, and retention of the H-V Diagram as a Limitation, to provide (operational) control of performance within the flight manual. This results in a situation where States rely upon alleviation from the Limitation of the H-V Diagram when operating offshore with more than nine passenger seats.
In the modern era, all helicopters operating offshore in Europe are certificated in Category A and B – i.e. they all comply with the Category A ‘build’ standard. Dual qualification permits these helicopters to be employed in ‘utility operations’ (aerial work) as well as ‘passenger transportation’ (commercial air transport – offshore and onshore).
All Category A and B procedures (from Subpart B ‘Flight’ of Part 29) ensure that the helicopter can tolerate an engine failure on take-off or landing: for Category A, by providing profiles that have demonstrated engine-failure accountability; and, for Category B, by mandating take-off and landing profiles that remain clear of the H-V avoid curve.
All dual qualified helicopters have a ‘capability’ (as expressed in the EASA definition of Category A) of using the Category A or Category B procedures; helicopters cannot be ‘operated’ in Category A or Category B they have to be ‘operated’ in accordance with the Performance Classes (or with exposure) – i.e. it is the performance code that determines which Performance Class has to be employed. Certification in Category A does not mandate the use of the Category A procedures.
The significant intent of the changes to Part 29.1 as a result of NPRM 80-25, was to remove the H-V Diagram as a Limitation for ‘utility operations’ (aerial work) and, for simplicity, to bind that to a seating configuration of less than 10. Offshore operations (or any Commercial Air Transport) should not be regarded as ‘utility operations’; for that reason, more sophisticated methods of regulation need to be employed.
The one inescapable fact that results from Part 29.1 is that unless Category A procedures are mandated, the H-V Diagram is a Limitation when more than nine passengers are carried.
In NPA 2014-19; the proposed amendment to CS-29 – particularly in operations with more than nine passengers – is legally questionable, undermines the logic and intent of Part 29.1, and introduces doubt and unnecessary complication into the certification process; in order to preserve a world-wide harmonised code, it should not be undertaken. The introduction of Category B to Performance Class 2 requirements adds complications to the code under circumstances where the sole intent is to avoid the H-V Limitation (i.e. to circumvent CS-29.1 and CS-29.1517).
In the short term; a much simpler/better method would be to preserve the status quo (in Europe and world-wide) by: prepending an enabling clause into Subparagraph 4.a of the essential requirements; and, by adding an alleviating clause into CAT.POL.H.305. The decision not to proceed with this option should be revisited, or justification - acceptable to interested parties - provided.
In the long term; there is need for discussions between the Certificating Authorities about the removal of the H-V Diagram as a Limitation from Part 29.
Jim
Last edited by JimL; 27th Sep 2014 at 06:54.
The Nexus between the Certification and Operational Codes
It is axiomatic that operations should not be regulated from within a certification code; operations are dynamic and have to adapt to changing demands, whilst a certification code is (and has to be) somewhat static.
The seat of the ‘H-V Limitation’ issue results from a situation where some States have not provided a performance code in compliance with ICAO Annex 6, Part III, Chapter 3.1.1:
Hence, undue reliance has had to be placed upon limitations within the certification code to constrain operations; for obvious reasons, this method results in a coarse device with a singular granularity which has required alleviation to be provided for offshore operations. Using a code of performance permits a much finer granularity with risk assessment at its core.
The absence of a code of performance results in a situation where operations are (erroneously) described (by airworthiness personnel) in certification terms. The implied logic of NPA 2014-19 is that operations are performed either using the Category A or Category B procedures when the fact is that helicopters are certificated in Category A and/or Category B and are operated in Performance Classes 1, 2 or 3.
Note 1: Following the logic and intent of NPRM 80-25, the phrase ‘Category A operations’ in the AC 29-2C guidance is intended to refer to ‘passenger transportation’ rather than ‘utility’ operations (aerial work).
Note 2: If compliance with Category B procedures was required, then the fulfilment of CS 29.63 would require a defined take-off surface over which a landing can be made safely at any point along the flight path if an engine fails (not exactly in line with an offshore take-off).
Provision of procedures in accordance with Category A or Category B provides a capability (the term used in the definition of Category A) which can be employed in operations. The requirements for operation in the appropriate Performance Class is described in the code of performance; that there is no direct correlation between the certification Categories and Performance Classes is of little importance. Thus, Performance Class 2 provides the flexibility that is required, for operations other than from airports, with a Category A mass without the constraints of a Category A procedure but with appropriate levels of safety set in accordance with the risk profile of the operation.
It would be much better if H-V Diagram as a Limitation was removed. However, it is necessary to recognise that a situation exists where some (important) States, in the absence of a code of performance, require the certification code to contain operational restrictions. In the short term, a harmonised certification basis is more important that the fact that a directed alleviation from the Flight Manual Limitations has to be provided.
What is essential, is that airworthiness and operations personnel understand the nexus between certification and operations and share a single view of how they interact. What can be seen from the narrative of NPA 2014-19 is that more time needs to be set aside so that all personnel can read into and understand the underlying philosophy and concepts of the code of performance. Misconceptions enshrined in the NPA such as “Flight regimes subsequent to DPBL and prior to DPATO are therefore not within the scope of Category A according the definitions of Annex 1” have to be corrected.
Specifically, it must be made clear that “capable of operations using take-off and landing data…” does not result in an imperative to use such data – only the limitations have to be observed! The ICAO/JAA/EASA definition of Category A differs from the FAA version which contains the words “utilizing scheduled takeoff and landing operations...” a difference in the ICAO/JAA/EASA definition that was deliberately phrased at the time when the Performance Classes were being defined and incorporated into ICAO Annexes 6, 8 and 14 by the Heliops Panel.
The confusion of the NPA is exemplified in Paragraph 2.6.3 - CS 29.1587 Performance Information:
Jim
It is axiomatic that operations should not be regulated from within a certification code; operations are dynamic and have to adapt to changing demands, whilst a certification code is (and has to be) somewhat static.
The seat of the ‘H-V Limitation’ issue results from a situation where some States have not provided a performance code in compliance with ICAO Annex 6, Part III, Chapter 3.1.1:
3.1.1 Helicopters shall be operated in accordance with a code of performance established by the State of the Operator, in compliance with the applicable Standards of this chapter.
The absence of a code of performance results in a situation where operations are (erroneously) described (by airworthiness personnel) in certification terms. The implied logic of NPA 2014-19 is that operations are performed either using the Category A or Category B procedures when the fact is that helicopters are certificated in Category A and/or Category B and are operated in Performance Classes 1, 2 or 3.
Note 1: Following the logic and intent of NPRM 80-25, the phrase ‘Category A operations’ in the AC 29-2C guidance is intended to refer to ‘passenger transportation’ rather than ‘utility’ operations (aerial work).
Note 2: If compliance with Category B procedures was required, then the fulfilment of CS 29.63 would require a defined take-off surface over which a landing can be made safely at any point along the flight path if an engine fails (not exactly in line with an offshore take-off).
Provision of procedures in accordance with Category A or Category B provides a capability (the term used in the definition of Category A) which can be employed in operations. The requirements for operation in the appropriate Performance Class is described in the code of performance; that there is no direct correlation between the certification Categories and Performance Classes is of little importance. Thus, Performance Class 2 provides the flexibility that is required, for operations other than from airports, with a Category A mass without the constraints of a Category A procedure but with appropriate levels of safety set in accordance with the risk profile of the operation.
It would be much better if H-V Diagram as a Limitation was removed. However, it is necessary to recognise that a situation exists where some (important) States, in the absence of a code of performance, require the certification code to contain operational restrictions. In the short term, a harmonised certification basis is more important that the fact that a directed alleviation from the Flight Manual Limitations has to be provided.
What is essential, is that airworthiness and operations personnel understand the nexus between certification and operations and share a single view of how they interact. What can be seen from the narrative of NPA 2014-19 is that more time needs to be set aside so that all personnel can read into and understand the underlying philosophy and concepts of the code of performance. Misconceptions enshrined in the NPA such as “Flight regimes subsequent to DPBL and prior to DPATO are therefore not within the scope of Category A according the definitions of Annex 1” have to be corrected.
Specifically, it must be made clear that “capable of operations using take-off and landing data…” does not result in an imperative to use such data – only the limitations have to be observed! The ICAO/JAA/EASA definition of Category A differs from the FAA version which contains the words “utilizing scheduled takeoff and landing operations...” a difference in the ICAO/JAA/EASA definition that was deliberately phrased at the time when the Performance Classes were being defined and incorporated into ICAO Annexes 6, 8 and 14 by the Heliops Panel.
The confusion of the NPA is exemplified in Paragraph 2.6.3 - CS 29.1587 Performance Information:
A change to the paragraph itself is not proposed, but an AMC to sub-paragraph (b)(6) is included. The AMC will clarify that for helicopters certified to both Category A and Category B the H-V envelope is a limitation only when operating according to Category A, and is performance information when operating according to Category B. This fulfils the objective defined for the RMT.
In a single paragraph we have the nub of the problem; the text implies that ‘when operating according to Category A’ means using the Category A procedures. As has been shown above, Category A provides a capability that may be used in support of a Performance Class – it is not an imperative. This is confirmed by the last paragraphs of AC 29.1583(b)(8)(i) which states that the H-V Diagram can only be omitted from the Limitations Section if the Category A procedures are mandated:Therefore, if the Category A takeoff and landing profiles, procedures, and WAT limitations are adequately and clearly defined in the RFM, this information is considered sufficient for compliance with the requirements of § 29.1583(f) without the inclusion of an actual HV diagram. The Category A procedures and profile definitions may be presented in the normal procedures or performance sections of the RFM but should be referenced as being mandatory requirements in the limitations section unless an HV diagram valid for Category A operations is presented.
There can be no misunderstanding of the intent of this passage; unless the Category A procedures are mandated, an H-V Diagram is required in the Limitations section. Ipso facto, if the H-V Diagram is in the Limitations section, the Category A procedures are not mandated (unless so specified in the Operational Regulations).Jim
If I may further seek your indulgence .
Understanding the difference between Limitations and Performance Information
In order to understand the difference between limitations and information it is necessary to examine two rules – CS 29.1583 and CS 29.1587. Firstly, we have to look to CS 29.1583 (‘Operating limitations’) to see what is mandated: for category A rotorcraft it is the maximum mass (in accordance with CS 29.25, CS 29.1519 and CS 29.1583(c)) and the H-V Diagram (in accordance with CS 29.87, CS 29.1517 and CS 29.1583(f)).
It is only when we look to CS 29.1587 (‘Performance Information’) that we find the Category A: airspeeds; techniques; rejected and take-off distances; landing data; climb data; and hover performance.
It is important that the difference between limitations and information is observed and understood.
If it is considered that, for an aircraft certificated in Category A, no departures/arrivals should be conducted outside of the profiles/procedures contained in the Category A Supplement of the RFM, passenger operations would be constrained in an unacceptable way. Particularly when a limited number of procedures/profiles are defined and operations are not always conducted from airfields.
As an example, look at the clear area procedure of the AW 189: this requires a ground run to 25 kts ground speed to comply with the procedure. One difference between Performance Class 2 and Performance Class 1 is that, whilst Performance Class 1 requires a surface on which a ‘reject’ can be carried out to the ‘limit load’ (also known as the serviceability limit) of the undercarriage (CS 29.725), the ‘safe-forced-landing’ of Performance Class 2 permits the ‘reject’ to be carried out to the ‘ultimate load’ (CS 29.727).
Note: ‘safe forced landing’ means an unavoidable landing or ditching with a reasonable expectancy of no injuries to persons in the aircraft or on the surface.
Compliance with Performance Class 2 is permitted over a surface which would not permit a ground run but, in the event of a power unit failure, would be suitable for a safe-forced-landing (for example a rough grass surface).
There appears to be no good reason why the clear area procedure could not be conducted with a normal departure from the hover; however, to comply with the Category A Supplement, it must be flown as published (with a ground run). Operations in Performance Class 2 would permit a hover departure mirroring the Category A procedures (but without ground run) at 8,300kg. However, this appears to be precluded because the ‘reject’ graph (substituting for the H-V Diagram) does not permit a take-off mass in excess of 7,900kg. (The gap in the upper end of the ‘reject’ graph could easily be filled by providing an appropriately constructed mini H-V Diagram.) The situation is exacerbated by the lack of a Category A WAT in the Limitation Section in compliance with CS 29.25, CS 29.1519 and CS 29.1583(c).
Note: the category A WAT (common to all Category A procedures) is one which is constructed to show compliance with CS 29.25(a)(2) and CS 29.67(a)(2).
Jim
Understanding the difference between Limitations and Performance Information
In order to understand the difference between limitations and information it is necessary to examine two rules – CS 29.1583 and CS 29.1587. Firstly, we have to look to CS 29.1583 (‘Operating limitations’) to see what is mandated: for category A rotorcraft it is the maximum mass (in accordance with CS 29.25, CS 29.1519 and CS 29.1583(c)) and the H-V Diagram (in accordance with CS 29.87, CS 29.1517 and CS 29.1583(f)).
It is only when we look to CS 29.1587 (‘Performance Information’) that we find the Category A: airspeeds; techniques; rejected and take-off distances; landing data; climb data; and hover performance.
It is important that the difference between limitations and information is observed and understood.
If it is considered that, for an aircraft certificated in Category A, no departures/arrivals should be conducted outside of the profiles/procedures contained in the Category A Supplement of the RFM, passenger operations would be constrained in an unacceptable way. Particularly when a limited number of procedures/profiles are defined and operations are not always conducted from airfields.
As an example, look at the clear area procedure of the AW 189: this requires a ground run to 25 kts ground speed to comply with the procedure. One difference between Performance Class 2 and Performance Class 1 is that, whilst Performance Class 1 requires a surface on which a ‘reject’ can be carried out to the ‘limit load’ (also known as the serviceability limit) of the undercarriage (CS 29.725), the ‘safe-forced-landing’ of Performance Class 2 permits the ‘reject’ to be carried out to the ‘ultimate load’ (CS 29.727).
Note: ‘safe forced landing’ means an unavoidable landing or ditching with a reasonable expectancy of no injuries to persons in the aircraft or on the surface.
Compliance with Performance Class 2 is permitted over a surface which would not permit a ground run but, in the event of a power unit failure, would be suitable for a safe-forced-landing (for example a rough grass surface).
There appears to be no good reason why the clear area procedure could not be conducted with a normal departure from the hover; however, to comply with the Category A Supplement, it must be flown as published (with a ground run). Operations in Performance Class 2 would permit a hover departure mirroring the Category A procedures (but without ground run) at 8,300kg. However, this appears to be precluded because the ‘reject’ graph (substituting for the H-V Diagram) does not permit a take-off mass in excess of 7,900kg. (The gap in the upper end of the ‘reject’ graph could easily be filled by providing an appropriately constructed mini H-V Diagram.) The situation is exacerbated by the lack of a Category A WAT in the Limitation Section in compliance with CS 29.25, CS 29.1519 and CS 29.1583(c).
Note: the category A WAT (common to all Category A procedures) is one which is constructed to show compliance with CS 29.25(a)(2) and CS 29.67(a)(2).
Jim
Conclusion
The purpose of NPA 2014-19, is to provide alleviation from the H-V Diagram as an Operational Limitation by: amending CS 29.1; providing new AMC 29.1 and AMC 29.1587(b)(6); amending CAT.POL.H.300; and providing new AMC1 CAT.POL.H.300. The proposed solution is complex and relies for achievement of its objective in circumventing the intended requirement to apply the H-V Diagram as a Limitation when the aircraft is certificated as a Category A rotorcraft*, or when there are more than 9 passenger seats.
* Not 'certificated in Category A' but 'certificate as a Category A Rotorcraft'.
One inescapable fact that results from Part 29.1 is that, unless Category A procedures are mandated, the H-V Diagram is a Limitation when more than nine passengers are carried. In effect the changes proposed in NPA 2014-19 are an attempt to redefine the intent of CS 29.1 as established in NPRM 80-25 – which addressed the separation of ‘utility’ operations from ‘passenger transportation’.
Removal of the H-V Diagram as a Limitation requires more than just statements in guidance; the solution contained in NPA 2014-19 represents a substantial challenge to the intent of CS 29.1 – i.e. the requirement to apply CS 29.1517 for ‘passenger carriage’. This intent was explained/justified, when changes were made to the rule in NPRM 80-25. The proposed change to the intended function of 29.1 is unlikely to go unquestioned as it represents a breach in harmonisation under circumstances where regulation of performance in some States, depends upon the intended application of the rule.
The current method of alleviation, used in FAR 91.9(d) and Appendix 1 to JAR-OPS 3.005(c), is preferable because it is completely transparent and does not require a change in the intent or wording of CS-29.1; it preserves the status quo – both with respect to offshore operations, and harmonisation with the FAA. (The FAR/JAR solution was not transposed to EASA OPS because the requirement to comply with the Limitations of the RFM was placed in the Basic Regulations rather than in the Implementing Rules.)
The statement in NPA 2014-19:
cannot go unchallenged. Of course it is possible to make the changes shown below; in fact the solution, proposed in NPA 2014-19, shows less respect for the airworthiness code and the limitations that are represented in CS-29.1 than the current solution with its transparent, specified and limited alleviation backed by risk assessed procedures. The use of semantics to circumvent the intent of CS-29.1 will not provide the clarity that is achieved by the current alleviation; it also introduces a question mark into the world-wide interpretation of Part 29.1, and 29.1517 for States which rely upon the current intent to achieve regulation of operational performance.
A much simpler solution would be to amend the Essential Requirements to permit the well understood and measured solution that is currently used in FARs and JARs (the status quo ante). This could be achieved by using wording currently employed in the Basic Requirement for permitting alleviations; thereby facilitating the smallest change to EASA OPS whilst remaining completely transparent.
Article 8 – Air Operations, paragraphs 2 and 3, already contain precedents for the provision of a solution by having as the introduction to their text the phrase “unless otherwise determined in the implementing rules” – as follows:
All that is required is for Paragraph 4 ‘Aircraft performance and operating limitations’ - specifically subparagraph 4.a of the essential requirements to be be amended as follows:
Jim
The purpose of NPA 2014-19, is to provide alleviation from the H-V Diagram as an Operational Limitation by: amending CS 29.1; providing new AMC 29.1 and AMC 29.1587(b)(6); amending CAT.POL.H.300; and providing new AMC1 CAT.POL.H.300. The proposed solution is complex and relies for achievement of its objective in circumventing the intended requirement to apply the H-V Diagram as a Limitation when the aircraft is certificated as a Category A rotorcraft*, or when there are more than 9 passenger seats.
* Not 'certificated in Category A' but 'certificate as a Category A Rotorcraft'.
One inescapable fact that results from Part 29.1 is that, unless Category A procedures are mandated, the H-V Diagram is a Limitation when more than nine passengers are carried. In effect the changes proposed in NPA 2014-19 are an attempt to redefine the intent of CS 29.1 as established in NPRM 80-25 – which addressed the separation of ‘utility’ operations from ‘passenger transportation’.
Removal of the H-V Diagram as a Limitation requires more than just statements in guidance; the solution contained in NPA 2014-19 represents a substantial challenge to the intent of CS 29.1 – i.e. the requirement to apply CS 29.1517 for ‘passenger carriage’. This intent was explained/justified, when changes were made to the rule in NPRM 80-25. The proposed change to the intended function of 29.1 is unlikely to go unquestioned as it represents a breach in harmonisation under circumstances where regulation of performance in some States, depends upon the intended application of the rule.
The current method of alleviation, used in FAR 91.9(d) and Appendix 1 to JAR-OPS 3.005(c), is preferable because it is completely transparent and does not require a change in the intent or wording of CS-29.1; it preserves the status quo – both with respect to offshore operations, and harmonisation with the FAA. (The FAR/JAR solution was not transposed to EASA OPS because the requirement to comply with the Limitations of the RFM was placed in the Basic Regulations rather than in the Implementing Rules.)
The statement in NPA 2014-19:
Suggestion 1:
Change the Basic Regulation to allow deviations from the AFM when applicable.
Even if it is possible to include a paragraph in the Basic Regulation allowing dispensation or alleviation from the AFM limitations, the Agency has decided not to because respecting the airworthiness limitations is an accepted general principle which should be maintained.
By retaining this principle, the Basic Regulation, Annex IV, paragraphs 4.a and 8.b, as quoted in 2.1.3 (a), remains in effect.
In the Agency’s view this suggestions cannot be further considered.
Change the Basic Regulation to allow deviations from the AFM when applicable.
Even if it is possible to include a paragraph in the Basic Regulation allowing dispensation or alleviation from the AFM limitations, the Agency has decided not to because respecting the airworthiness limitations is an accepted general principle which should be maintained.
By retaining this principle, the Basic Regulation, Annex IV, paragraphs 4.a and 8.b, as quoted in 2.1.3 (a), remains in effect.
In the Agency’s view this suggestions cannot be further considered.
A much simpler solution would be to amend the Essential Requirements to permit the well understood and measured solution that is currently used in FARs and JARs (the status quo ante). This could be achieved by using wording currently employed in the Basic Requirement for permitting alleviations; thereby facilitating the smallest change to EASA OPS whilst remaining completely transparent.
Article 8 – Air Operations, paragraphs 2 and 3, already contain precedents for the provision of a solution by having as the introduction to their text the phrase “unless otherwise determined in the implementing rules” – as follows:
2. Unless otherwise determined in the implementing rules, operators engaged in commercial operations shall demonstrate their capability and means of discharging the responsibilities associated with their privileges. These capabilities and means shall be recognised through the issuance of a certificate. The privileges granted to the operator and the scope of the operations shall be specified in the certificate.
3. Unless otherwise determined in the implementing rules, operators engaged in the non-commercial operation of complex motor-powered aircraft shall declare their capability and means of discharging the responsibilities associated with the operation of that aircraft. That same wording should be used to amend Paragraph 4.a
3. Unless otherwise determined in the implementing rules, operators engaged in the non-commercial operation of complex motor-powered aircraft shall declare their capability and means of discharging the responsibilities associated with the operation of that aircraft. That same wording should be used to amend Paragraph 4.a
4.a Unless otherwise determined in the implementing rules, an aircraft must be operated in accordance with its airworthiness documentation and all related operating procedures and limitations as expressed in its approved flight manual or equivalent documentation as the case may be.
This would then permit the addition of a clause (c) into CAT.POL.H.305 ‘Operations without an assured safe forced landing capability’:CAT.POL.H.305 Operations without an assured safe forced landing capability
(a) Operations without an assured safe forced landing capability during the take-off and landing phases shall only be conducted if the operator has been granted an approval by the competent authority.
(b) To obtain and maintain such approval the operator shall:
…
(c) Momentary flight through the height velocity (HV) envelope is permitted during the take-off and landing phases.
That would leave only the editorial changes to be made.(a) Operations without an assured safe forced landing capability during the take-off and landing phases shall only be conducted if the operator has been granted an approval by the competent authority.
(b) To obtain and maintain such approval the operator shall:
…
(c) Momentary flight through the height velocity (HV) envelope is permitted during the take-off and landing phases.
Jim