View Full Version : Helicopter Height-Velocity (H-V) limitations
I see that EASA have published NPA 2014-19 'Helicopter Height-Velocity (H-V) limitations':
http://easa.europa.eu/system/files/dfu/NPA%202014-19.pdf
There are some interesting interpretations of the Certification rules of Part 29.1 (and others) which are bound to put EASA at odds with the FAA because it changes the intent of the rule as established in NPRM Notice No. 80-25. (In simple terms, it requires the H-V Diagram to be a limitation when the number of seats is 10 or more - thus requiring operations to be either Pure PC2 or PC1 for such helicopters.)
One of the interesting aspects of the NPA is the statement that flight in the H-V curve is governed by mass and not by height and speed; another is the concept of 'Category B operations' (or any other 'operating in Category' statement).
In the document, there are other strange statements - for example
"...the H-V envelope is a limitation only when operating according to Category A..."
Would someone like to explain that to me!
Suggestion 3 (which is really the crux of the matter) is dismissed with the following statements:
Change CS-29 to move the H-V envelope from the limitations section to the performance section in the AFM.
Moving the H-V envelope from limitations to performance criteria goes against the Category A certification philosophy and would be a non-trivial change. Furthermore, changing CS-29 in such a way would create a substantial difference with the similar FAA certification requirements, and may impact on type-validation and acceptance by foreign authorities [presumably the FAA].
It should also be noted that to obtain the expected effect of the suggestion, Category A take-off and landing weights would also need to be required transposed [their wording] from limitations to performance criteria. This would go against the regulatory desire and trend towards encouraging more powerful helicopters with full Category A engine failure accountability.
In the Agency’s view this suggestions cannot be further considered.
There are few who would not wish to see the H-V Diagram tranfered from the Limitations to the Performance Section. This would be no problem for those States who have a performance code (e.g. JAR-OPS 3 or EASA Ops) because protection for 'passengers'/'crew members' is already contained within the code. Operational regulations can permit risk assessment (limited exposure) and scaled (rules related to passenger numbers) or objective requirements and suitable methods of compliance.
That this will pass into regulations is not in doubt - offshore operations, in particular, need it. However, it would have been preferable either:
to correct the initial error of putting the requirement to apply the FM limitation into the 'law' - leaving compliance and alleviation to be achieved as it is with FAR 91.9 or JAR-OPS 3.005(c); or, better still
applying Suggestion 3.
This exercise is unlikely to make regulations clearer.
Mars
212man
31st Jul 2014, 10:59
What a shambolic, rambling, innacurate prose. The NPA I mean - not Mars' ;)
Perhaps I am having problems because of my English comprehension; for example paragraph 2.6.2:
2.6.2. CS 29.1 Availability
It is proposed to change the paragraph to ensure that multi-engined helicopters may be certified both Category A and Category B with appropriate and different operating limitations for each category.
For helicopters with MTOM greater than 9072 kg and 10 or more passenger seats, it is already stated in CS 29.1(c) that Category A approval is required.
Clarification is given that only helicopters certified solely to Category B are affected by the additional limitations which are normally associated with Category A. Where a Category B approval is a stepping stone before gaining a Category A approval, the additional Category A limitations will not be applied as part of the Category B approval. Helicopters with MTOM greater than 9072 kg but with less than 10 passenger seats (CS 29.1(d)) and helicopters with MTOM less than 9 072 kg but with more than 10 passenger seats are within this regulatory frame.
This allows all large multi-engined helicopters to be type certified as both Category A and Category B with appropriate and different operating limitations, as defined in CS 29.1(b). This aligns with the change to CAT.POL.H.300, and ensures that the objective defined for the RMT is fulfilled.
An accompanying AMC regarding certification standards will be included.
Firstly, what does the heading mean or imply? Is it a spelling mistake - should it be 'Applicability'?
It is important to understand the reason behind the 'NPRM 80-25' amendment to FAR 29.1 (no JARs at that time) that resulted in, what is in effect, quite a complicated set of clauses in the rule. Prior to 80-25, all helicopters certificated in the Transport Category had the H-V Diagram as a limitation unless a specific alleviation was sought from the FAA (each an individual application).
During the late 70, it became evident that Part 29 helicopters (Transport Category) were not only being used for passenger transport but were increasingly in demand for utility tasks; it was clear that for such tasks (Aerial Work) it was not necessary (nor was it possible) to retain the HV diagram as a limitation. A comprehensive proposal was put forward in NPRM Notice No. 80-25 to provide differentiation between Utility and Passenger Transportation along with appropriate standards. Adopting the philosophy applied to fixed wing aircraft in Appendix A to Part 135 (and using a similar justification), it was proposed to retain the higher standard only for the carriage 10 or more passengers.
However, because of the high cost of production and operation of helicopters this distinction could not be ‘hard’; it was clear that helicopters could (and would) be configured for both utility and passenger roles. In recognition of this, Part 29.1 was re-constructed to permit both Category A and Category B standards to be applied to a single helicopter type. The practical result of this dual certification was not a variation in the build standard for the helicopter type, but:
the removal of the HV diagram as a limitation; and
the removal of the requirement to provide most of the performance data
when the helicopter was operated in the Utility Role.
However, to ensure that this easement was not abused, Part 29.1(b) contained a clause requiring the provision of a supplement when the helicopter was being used in the Utility Role:
CS 29.1 Applicability
…
(b) Transport category rotorcraft must be certificated in accordance with either the Category A or Category B requirements of this Part. A multiengine rotorcraft may be type certificated as both Category A and Category B with appropriate and different operating limitations for each category. [my underlining]
What the clauses to the rule made clear however, was that whenever the helicopter was in the 10 seat configuration, the H-V Diagram applied as a limitation.
So, back to the original quotation and the second paragraph:
2.6.2 CS 29.1 Availability [Applicability]
...
For helicopters with MTOM greater than 9072 kg and 10 or more passenger seats, it is already stated in CS 29.1(c) that Category A approval is required.
...
Is my understanding correct that for a helicopter with a MCTOM of more than 20,000 lbs and 10 or more seats the H-V Diagram remains a limitation?
If not, why not?
Mars
Perhaps some basic information would be of assistance.
Helicopter certification is split between Parts 27 (small/normal) and 29 (large/transport). The mass break is at 3,175 kg (7000 lbs). All helicopter with a mass exceeding 3,175 kg must be certificated in accordance with Part 29. (We will return to Part 27 and Category A later.)
Large/Transport helicopters are certificated to Category A or Category B (or in some cases both) in accordance with their mass and passenger seats – the breaks for these Category divisions are: mass greater than 9,072 kg (20,000lbs); passenger seat of 10 or more (as stated in a previous post less than 10 seats is regarded as ‘utility’ and 10 or more as ‘passenger transportation’).
We will not dwell on the build standard but those helicopter with mass greater than 9,072 kg (20,000 lbs) and/or for ‘passenger transportation’ always have to satisfy the Category A requirements of Subparts C, D, E and F. That leaves the helicopter with a mass of 9072 kg or less and nine or less passengers which can be certificated to Category B.
Helicopters with 10 or more passengers seats have the H-V Diagram as a limitation and have to provide Category A performance data: for the helicopter in excess of 7,092 kg it is the full suite; for the helicopter of 7,092 kg or less it is the second segment climb performance (which is basic PC2 performance requirement).
Note: Helicopters operating in PC1 have to have the full Category A data suite – including those with a mass of 3,175 or less. As all helicopter have to meet the PC1 requirement when 200ft above the take-off/landing site, it is expected that they will have the full data suite.
If a helicopter is certificated in both a ‘utility’ configuration (i.e. less than 10 seats) and a ‘passenger transportation’ configuration, separate operating limitations are required – these can usually be found in the Flight Manual as a ‘9 seat Supplement’. Such a supplement usually states that the H-V Diagram is no longer a ‘limitation’ but is performance information.
When operating offshore (and occasionally onshore) in the ‘passenger transportation’ configuration (10 or more seats) and not flying within a Category A procedure, it is likely that there will be excursions into the H-V curve. Knowing that is the case, both JAR-OPS and Part 91 provided alleviation (for JAR-OPS that extended beyond over-water operations). That could be done because the requirement to apply the Flight Manual limitations, was contained in the (same) regulation and not in the Law (EASA Essential Requirements).
Having made the basic error of putting the requirement to apply the Flight Manual limitations in the Law, EASA had to remove the alleviation (taken from JAR-OPS 3) from the draft EASA OPS. The NPA proposes a (very complex and convoluted) method under which the H-V limitation can be circumvented. Clearly this solution is driven by expediency in that it does not have to tackle the basic problem (an attempt to regulate operations from a certification code) or address the error made by putting the Flight Manual limitation within the Law.
The intent of Part 29.1 is to provide a method of permitting two types of operation with one type of helicopter: the first is ‘passenger transportation’ – for which Category A procedures and data are provided in order to permit the highest standards to apply; and the second ‘utility operations ‘ - when such procedures and data are not required to be provided and alternative standards are permitted (thus removing the necessity to establish Category A procedures – quite a lengthy and costly exercise).
Thus we have the first ‘imperative’ of the rule: when operating with ten or more passengers, procedures and data will be available and flight inside the H-V curve is prohibited! No amount of obfuscation or misinterpretation of the rules can disguise this imperative.
However, NPA 80-25 made clear that the change in applicability was an opportunity for manufacturers to broaden the use of their helicopters by providing for both configurations in a single type; this required a second intent to be enumerated in Part 29.1(b)! When a manufacturer wished to provide for both types of operation – ‘passenger transportation’ and ‘utility’ – the distinction between them had to be made clear by the provision of “different operating limitations for each category”. As explained previously, this is usually achieved with the use of a ‘9 seat RFM Supplement’.
When a helicopter has been manufactured and certificated for both ‘utility’ and ‘passenger transportation’, it has met the higher build standard, the RFM has the applicable Category A procedures and data, and the H-V diagram is a limitation. The principle content of the 9 seat supplement therefore is the provision of a derogation from the H-V diagram.
Under the JAA/EASA, there is no compulsion to apply the Category A procedures unless Performance Class 1 operations are mandated (and even then, requirements are objective and alternative procedures can be used). However, under the FAA regulations, this is not so clear. This is because the definition of Category A differs between the two Authorities. The two definitions are - for the FAA:
Category A, with respect to transport category rotorcraft, means multiengine rotorcraft designed with engine and system isolation features specified in Part 29 and utilizing scheduled takeoff and landing operations under a critical engine failure concept which assures adequate designated surface area and adequate performance capability for continued safe flight in the event of engine failure.
and, for the JAA/EASA/ICAO:
Category A, with respect to rotorcraft, means a multi-engined rotorcraft designed with engine and system isolation features specified in CS–27 / CS–29 and capable of operations using take-off and landing data scheduled under a critical engine failure concept which assures adequate designated surface area and adequate performance capability for continued safe flight or safe rejected take-off in the event of engine failure.
As can be seen from the JAA/EASA/ICAO definition, for operations in Performance Class 2 any profile can be utilised providing there is no flight through the H-V curve. (As a matter of interest, the Category B profile mandated under Part 29 also requires flight outside the H-V curve.) In Performance Class 2 there is no compulsion to apply any profile contained in the RFM; in Pure Performance Class 2 if there is an engine-failure, a safe-forced-landing is required (out of the H-V curve and over an adequate surface); in Performance Class 2 with exposure, the condition of a safe-forced-landing are waived for a limited period.
However, when operating with ten or more passengers, the H-V diagram is a limitation and, when operating Performance Class 2 with exposure, the derogation provide by Appendix 1 to JAR-OPS 3.005(c) is required.
Up to the time that EASA removed the JAR-OPS 3.005(c) provisions (requirement and alleviation) from the operational regulation, there was no doubt about the intent of the 29.1 – all of the North Sea fleet had been (as required by the operational regulations) certificated in Category A and were operating with exposure.
Clearly a resolution is required but not one that ‘hacks’ the operational code and provides some bizarre interpretation of the certification code.
The least disruptive (in the sense of the negotiations that will be required between the FAA and EASA) would be to amend the Basic Requirements and re-introduce the mechanism for specific alleviation. The best solution would be for Authorities to accept the realities of operations, remove the H-V diagram as a limitation, and have it as information.
That the latter solution is difficult to achieve is because the FAA have never been able to regulate performance with the operational requirements (as they have for fixed-wing) and have to resort to doing so from the certification code.
Jim
HeliTester
2nd Aug 2014, 22:23
Jim,
I found EASA NPA 2014-19 to be a difficult read. Then after reading your comments and considering the intent of the NPA expressed in the executive summary, I find myself asking the (possibly dumb) question…wasn’t this issue adequately addressed previously via JAR-29 and JAR-OPS 3? Does this issue arise because JAR-29 and JAR-OPS 3 did not migrate word-for-word into CS-29 and EU OPS?
HT
212man
3rd Aug 2014, 09:50
HT, that's how I understand it.
HeliTester,
With respect to Part 29 (FAR 29 and CS-29); this is a substantially harmonised document with no differences in the text that is being discussed in the NPA (or on here). EASA are proposing a slight change to CS-29.1 that is insignificant to the problem in hand but will take CS-29 out of harmonisation with FAR 29. Those changes are 'cosmetic' and have no substantial effect on the 'intent' of Part 29.1.
Yes, as previously stated, the alleviation that was established by Part 91.9(d) was copied over to JAR-OPS 3, incorporated in Appendix 1 to JAR-OPS 3.005(c), and widened slightly to include all operations with exposure.
When JAR-OPS 3 was transposed to EASA OPS, the alleviation was copied across verbatim. When the draft was submitted, EASA lawyers removed the alleviation stating that the Essential Requirements could not be alleviated from within the Operational Regulations. The removal of the alleviation resulted in the challenge to the effect that offshore operations with 10 or more passengers would be placed outside the law - i.e. the majority of North Sea Operations! There was no response from the lawyers.
The prevailing mindset in the NPA is that 'operations' are performed in in ‘Category A’ or ‘Category B’; this can be seen in the narrative of paragraph 2.1.2 of the NPA:
...
In addition, PC2 regulations for take-off and landing allowed operations which were not within the scope of Category A. This constituted a regulatory mismatch with the Category A certification requirement. This was not further approached by the JAA.
...
The reason it was not approached by the JAA was because the ‘helicopter operations committee’ understood extremely well the distinction between a ‘helicopter’ that was certificated in Category A and Operations in Performance Classes 1 and 2. Knowledge that now appears to be lost to EASA.
In fact what certification in Category A ensures is a build standard, limitations, and the provision of performance procedures and data; how/when those procedures and data are used and how helicopter is subsequently operated is a matter for the operational requirements.
When it comes to the critical point of the NPA; there is no effective (legal) difference between the text of Appendix 1 to JAR-OPS 3.005(c):
(a) For helicopters certificated in Category A, a momentary flight through the height velocity (HV) envelope is allowed during the take-off and landing phases, when the helicopter is operated according to any of the following requirements: [take-off/landing with exposure]
and CAT.POL.H.300
(b) Helicopters operated in performance class 2 without an assured safe forced landing capability during the take-off and landing phases shall be certified in both Category A and Category B or equivalent as determined by the Agency.
(c) Operations defined in (b) shall be conducted subject to the AFM limitations of Category A, except prior to the defined point after take-off (DPATO) and after the defined point before landing (DPBL) where Category B limitations may apply.
Except the JAA extract is direct and to the point and the EASA extract is not (they both provide a derogation from the limitation of the H-V Diagram when operating a helicopter with 10 or more seats).
The following extract from the AMC to 300 is also extremely badly written (mixes mass and weight, appears to align the H-V Diagram with mass, and makes little sense). It also appears to relate the ‘available take-off and landing area’ with the ‘FATO’ (which cannot be the case with exposure).
(a) UTILISING CATEGORY B LIMITATIONS
Within the area defined in CAT.POL.H.300(c), Category B limitations may only apply if:
(1) a Category A procedure is impractical and the authorised take-off weight and landing masses would penetrate the height-velocity envelope during a performance class 2 take-off or landing; and/or
(2) the available take-off and landing area (FATO) would not allow a safe forced landing following a failure of the critical engine.
I have no wish for this to be a monologue or dialogue but it is an opportunity to provide information that is not generally well known (because it is at the nexus of certification and operations).
As was previously stated, the NPA makes a great deal of the discrepancy in mass between Category A and Category B and the effect on the H-V diagram. With respect to all operations in Performance Class 2, the maximum mass is given by the requirement (in the operational regulations) to meet the second segment climb performance*. This mass is provided in the basic Category A WAT required in accordance with Part 29.25(a) - for each density altitude for which the Category A performance and procedures are based. The data that is required to comply with this requirement is specified in Part 29.67(a)(2) – required for all helicopters with 10 or more passengers seats (and, in accordance with current operational requirements, for all helicopter operating in Performance Classes 1 & 2).
* When PC2 operations with exposure are planned (flight into the H-V curve), the mass may be further limited by the requirement for an AEO OGE hover in still air; for some helicopters, this might be more limiting than the second segment climb requirement.
This may be esoteric but the outcome of this is that, even if they exist in the RFM, Category B masses are not permitted to be used; ipso facto, there is only one H-V diagram that applies, even if more than one is present (which is often not the case). The question of mass and the H-V diagram is a red herring – albeit extensively mentioned in the NPA. Incursions into the H-V curve are as a result of the (usually vertical component of the) take-off and/or landing manoeuvre – when operating outside a Category A profile.
I am conscious of this now becoming a monologue and I apologise for that; however, it is important that statements made in regulatory documents, such as NPAs, do not go unchallenged when they are incorrect or are based upon the author’s opinion – rather than fact.
I would like you to consider Suggestions 3 (which I have referred to before) and 6 but prior to this, I want to debunk one or two of the ‘facts’ in the NPA. In my previous post, I mentioned the lack of relevance of the take-off mass to this issue. The mass limits provided in the limitations section have to be provided in accordance with Part 29.25(a); these masses are derived from:
The maximum design mass (showing compliance with the structural loading conditions);
The highest mass as which compliance with each applicable flight requirement is shown;
For Category B rotorcraft with 9 or less seats the maximum weight/altitude/temperature (WAT) at which the rotorcraft can operate safely near the ground.
The maximum Category A mass is provided by a WAT curve that meets the second segment climb performance (modified, if required, by the maximum design mass). It should come as no surprise to find that the maximum mass for one of the larger helicopters used offshore is (almost) identical for Category A and B.
We find a similar situation with respect to the H-V diagram; if the maximum mass is identical for Category A and B, then the H-V diagram will also be identical – as evidenced in the RFM of the helicopter mentioned above. (The Category A H-V diagram is contained in the Limitations Section whilst the identical H-V diagram is in the Performance Section.)
With respect to Category B; hover performance IGE and OGE have to be provided as does the AEO climb and angle of glide. The most important element however, is the establishment of the take-off and landing profiles. These have to be shown to be outside the H-V curve providing, respectively, a take-off and landing distance. The take-off distance requires an acceleration below the bottom of the H-V curve, commencing the climb when past the knee; the distance is measure from the hover to the 50ft point.
You will immediately see the lack of any relevance of Category B masses and profiles to offshore operations. Let us now examine the two suggestions mentioned earlier:
Suggestion 3:
Change CS-29 to move the H-V envelope from the limitations section to the performance section in the AFM.
Moving the H-V envelope from limitations to performance criteria goes against the Category A certification philosophy and would be a non-trivial change. Furthermore, changing CS-29 in such a way would create a substantial difference with the similar FAA certification requirements, and may impact on type-validation and acceptance by foreign authorities.
It should also be noted that to obtain the expected effect of the suggestion, Category A take-off and landing weights would also need to be required transposed from limitations to performance criteria. This would go against the regulatory desire and trend towards encouraging more powerful helicopters with full Category A engine failure accountability.
In the Agency’s view this suggestions cannot be further considered.
Whilst it is correct that making this change would create a substantial difference between EASA and the FAA it would only be because, in the absence of other requirements, the protection that is necessary in a 10 or more passenger configuration would be removed from the FARs. However, when it is considered that this is already the case with offshore operations (by dint of the FAR 91.9(d) alleviation) the impact would only be felt for onshore operations with 10 or more passengers. With the exception of departure from an onshore base to offshore location, there can’t be too many other of those operations. If some scheduled transportation service were to be commenced, it could be forced to use Category A procedures by an OpSpec or some other regulatory device.
With respect to the last paragraph, it would not require the transposition from limitation to performance criteria, with the exception of the basic Category A WAT, they are already contained in the RFM Supplements – and would continue to be so. If it is being hinted here that provision of the Category A procedures requires the Category A H-V Diagram to be in the Limitations Section, we can put EASA’s mind at rest because of the statement in AC 29.53A(a)(1) Take-off: Category A:
If an engine failure is recognized at the Takeoff Decision Point (TDP) or at any point in the takeoff profile prior to attaining TDP, the rotorcraft must be able to land safely within the established rejected takeoff distance. Flight testing to determine the Category A rejected takeoff distance is very similar to height-velocity testing and should be approached with caution. The initial Category A takeoff profiles should be outside of the avoid area of the Category B height-velocity envelope.
Of course it has to say this because, there is no requirement for a Category A H-V Diagram in the Limitations Section if the Category A procedures are mandated in the RFM.
Proceeding now to suggestion 6:
Suggestion 6:
Change Regulation (EU) No 965/2012 to allow dispensation from the AFM limitations to allow short time penetration of the H-V curve during PC2 take-off and landing.
Regulation (EU) No 965/2012 cannot include a paragraph allowing dispensation or alleviation from airworthiness criteria defined in the AFM as it would be in conflict with the Basic Regulation.
In the Agency’s view this suggestions cannot be further considered.
Bearing in mind that the whole intent of this NPA is to circumvent a requirement in Part 29.1, it is incomprehensible that EASA have not used the precedent previously set; in Article 8 “Air Operations” of the Basic Regulation we find the following two paragraphs:
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.
This would only require paragraph 4.a of the essential requirements to be amended as follows:
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 facilitate a change permitting momentary flight through the H-V curve. Such a rule would be contained within the appropriate Implementing Rule and would not therefore be open to abuse. This would reflect the procedure the FAA used with Part 91.9(d).
Jim
“Oh what a tangled web we weave when first we practice to deceive!”
To continue:
The NPA, in seeking to circumvent the Part 29.1 requirement, muddies the principle that was established and agreed in ICAO Annex 6 and JAR-OPS 3 - shown in ICAO Annex 6, Attachment A, Chapter 2.1 as:
2.1 Helicopters operating in performance Classes 1 and 2 should be certificated in Category A.
This principle, which was discussed extensively before it was incorporated into Annex 6 and JAR-OPS 3, was adopted because it was felt necessary for helicopters operating over a hostile environment to be constructed to the highest standard, fulfilling the build requirements of Category A (as described in AC 29.1):
…provides the most rigid rules, requiring multiengine design with independent engines, fuel systems, and electrical systems. Category A design requires that no single failure can cause loss of more than one engine. Although there is no limit on maximum weight, Category A rotorcraft are certificated at a weight which will assure a minimum climb capability in the event of engine failure and with adequate surface area to assure a safe landing in the event an engine fails anywhere in the flight envelope, including takeoff or landing operations.
The requirement for certification in Category A was seen as necessary for helicopters that were intended for ‘unlimited’ operations over an environment that would not have permitted a safe-forced-landing or would have resulted in casualties due to the environment - in the context of this NPA, offshore operations where Performance Class 2 is mandated.
The proposed text of CAT.POL.H.300 obfuscates this requirement by introducing the complication of certification in Category B (as was previously discussed, a requirement that was intended for utility operations with less than 10 seats, not passenger transportation):
3.1.1. CAT.POL.H.300 General
(a) Helicopters operated in performance class 2 shall be certified in Category A or equivalent as determined by the Agency.
(b) Helicopters operated in performance class 2 without an assured safe forced landing capability during the take-off and landing phases shall be certified in both Category A and Category B or equivalent as determined by the Agency.
(c) Operations defined in (b) shall be conducted subject to the AFM limitations of Category A, except prior to the defined point after take-off (DPATO) and after the defined point before landing (DPBL) where Category B limitations may apply.
The proposed text just adds complexity to a regulation where none is required.
If the amendment to paragraph 4.a of the essential requirements is accepted, all that is then required is the addition of a clause to CAT.POL.H.305 - meeting the original intent of Appendix 1 to JAR-OPS 3.005(c):
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) Momentary flight through the height velocity (HV) envelope is permitted during the take-off and landing phases.
(c) To obtain and maintain such approval the operator shall:
…
To recap then; the only changes that are required to the current set of regulations are:
The addition of the text “Unless otherwise determined in the implementing rule” to the start of paragraph 4.a of the Essential Requirements; and
The addition of new paragraph (b) above to CAT.POL.H.305.
All of the other changes proposed in the NPA, along with the badly written and unnecessary/misleading guidance, can be discarded.
Because the principle of this was already agreed and incorporated in JAR-OPS 3, the proposal can be contained in one or two pages and passed through as a formality.
Without the changes proposed above, the Limitation of the H-V Diagram will continue to apply to helicopters ‘with 10 or more seats’.
Jim
steve_oc
7th Aug 2014, 08:00
Unfortunately all proposals to change the Basic Regulation, as you suggest or otherwise, were met with flat refusal...
Steve,
You are absolutely correct that when this solution was first proposed in May 2013, it was reject out of hand. However, now that the EASA proposal has been published, the folly of that decision is clear for all to see.
When suggestion 1 is considered in detail:
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.
It can be seen that the phrase "respecting the airworthiness limitation is an accepted general principle which should be maintained" is totally disingenuous in the light of EASA's attempt to circumvent the certification requirement of 29.1(c) and (e).
However, what is crystal clear is that none of the obfuscation that is contained in the NPA will alter the fact that for a helicopter with 10 seats, the H-V Diagram is a Limitation. This is evidenced in the RFM of one of the larger types in current operation.
Jim
Let’s summarise what has been said so far:
The Issue (world-wide):
The take-off from an offshore location when not flying in accordance with a Category A procedure under conditions where the headwind component is less than the value at the knee of H-V curve, will be subject to momentary flight through the H-V avoid curve (due to the height of the helideck above the surface).
Helicopters certificated under Part 29 and with 10 or more seats (Part 29.1(c) and (e)) are required to have the H-V Diagram as a Limitation in the RFM in accordance with Part 29.1517.
In Europe, helicopter operating in Performance Class 2 are required to be certificated in Category A: such helicopters, when certificated under Part 29, have the H-V Diagram as a limitation in the RFM (helicopters certificated under Part 27 Appendix C are only required to have the H-V Diagram as performance information).
States mandate compliance with the Limitations of the RFM (known rules are JAR-OPS 3.005(c) and FAR 91.9(a)).
Current Solution:
States alleviate operators from the H-V Diagram Limitation under limited and risk assessed conditions.
Under FAR 91.9(d) the conditions are: flight from a heliport constructed over water in which a safe ditching can be accomplished; and, the helicopter is amphibious or equipped with floats.
Under Appendix 1 to JAR-OPS 3.005(c) the conditions are: the operator has an approval for operations with exposure.
Approaching Problem:
From October 2014 compliance must be shown with EASA OPS.
Under EASA OPS, the requirement to apply the limitations of the RFM are contained in the Essential Requirements of 4.a.
EASA have stated that they do not wish to provide a method of alleviation from the Limitations of the RFM and have removed the intent of Appendix 1 to JAR-OPS 3.005(c) from the performance code.
Ipso facto offshore operations will no longer have alleviation from the H-V Diagram Limitation; this impacts upon those flight for which flight through the H-V Diagram is necessary.
Solution – Long Term:
Remove the H-V Diagram as a Limitation from the requirements of Part 29.
Effect USA: because operational FARs do not contain a formal code of performance, they rely upon the conditions of FAR 29.1(c) and (e) (the H-V Diagram as a Limitation) to ensure that flights are conducted in accordance with (the equivalent of) Performance Classes 1 and 2*. For that reason, they are unlikely to accord with a proposal to amend Part 29.
* FAR 29.1(c) contains the conditions under which Performance Class 1 can be conducted and FAR 29.1(e) Performance Class 2. (These are signalled through the application of the Category A WAT – meeting the second segment climb requirements - and observance of the H-V Diagram; and, additionally for 29.1(c), the application of the Category A Procedures.)
Effect Europe: no detrimental effect - Europe is in compliance with ICAO Annex 6, Part III in showing compliance with Chapters 3.1.1 and 3.1.2:
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.
Note 1.— The code of performance reflects, for the conduct of operations, both the various phases of flight and the operational environment. Attachment A provides guidance to assist States in establishing a code of performance.
3.1.2 In conditions where the safe continuation of flight is not ensured in the event of a critical engine failure, helicopter operations shall be conducted in a manner that gives appropriate consideration for achieving a safe forced landing.
Note.— Guidance on “appropriate consideration” is contained in Attachment A, 2.4.
Solution – Short Term:
Provide alleviation from the requirement to apply the RFM Limitations under controlled conditions.
Effect USA: no change from the status quo.
Effect Europe: this will require the following amendments to the regulations:
The text “Unless otherwise determined in the implementing rule” has to be prepended to paragraph 4.a of the Essential Requirements; and
The addition of new paragraph (b) to CAT.POL.H.205 “Momentary flight through the height velocity (H-V) envelope is permitted during the take-off and landing phases.”
This will return the regulations to the status quo ante before EASA lawyers intervened in the transposition of JAR-OPS 3 to EASA OPS.
Other points that have been clarified in this thread:
Helicopter that are certificated in Category A have a build standard, appropriate limitations, and the provision of performance procedures and data. This build standard is directly related to flight over a hostile environment and for that reason is mandated for operations in Performance Classes 1 & 2.
A helicopter cannot be operated in Category A or Category B. Procedures/profiles under which flight is conducted are specified in the operational code of performance. The maximum mass under which flight can be conducted in Performance Class 2 is defined by the Category A take-off mass.
Even when operating with Exposure, the maximum mass is still provided by the Category A WAT.
Finally:
Category B has no relevance to operations in Performance Classes 1 or 2; its introduction into the narrative/solution contained in the NPA results from a lack of knowledge of the certification and operational requirements. Operations in Performance Class 2 never make reference to the Category B take-off mass or the Category B H-V Diagram.
Jim
Shawn Coyle
8th Aug 2014, 22:54
unless things have changed, I was taught that if you have a Category A supplement in a Part 29, 110+ pax machine, the supplement says that the limitation of the H-V no longer applies when using this supplement...
The Category A performance and procedures obviates the need for the H-V as a limitation. (at least in N. America)
Have things changed and I didn't notice?
Shawn - by way of background.
One of the complicating issues of this particular problem is the multi-threaded nature of Part 29 - which refers backward and forward in order to avoid redundancy (if something is only stated once then referred to, any changes that are necessary only have to be made to a single location). AC 29-2C is used to clarify some of these complexities but the logic of the regulation does require that it be studied and understood.
(Please be tolerant and follow this through, the point comes at the end of the series of quotes.)
The requirement for the H-V Diagram data provision is contained in Part 29.87 – Height Velocity Envelope:
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…
This applies equally to certification in Category A and Category B. It is Part 29.1517 which requires this H-V Diagram to be provided as a Limitation:
CS 29.1517 Limiting height-speed envelope
For Category A rotorcraft, if a range of heights exists at any speed, including zero, within which it is not possible to make a safe landing following power failure, the range of heights and its variation with forward speed must be established, together with any other pertinent information, such as the kind of landing surface.
The requirement for the H-V Diagram as an operating limitation is described in Part 29.1583(f)
CS 29.1583 Operating limitations
(f) Limiting heights. Enough information must be furnished to allow compliance with CS 29.1517.
AC 29.1583 makes quite clear, in the final sentence of section (b)(8)(i), conditions under which an H-V Diagram can be omitted from the limitations section:
“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.”
Category A procedures and profiles are designed and flight tested to ensure that they meet engine-failure accountability and achieve flight/touchdown within the ‘serviceability limit’ of the helicopter (when flown as published, and on/over surfaces/areas which have been established for the purpose). They are a precision tool!
The H-V diagram is (usually) flight tested at the extremes of operation to provide a single graph (in some sense the provision of a rule-of-thumb for safe operations). It is a blunt instrument!
As you can see from AC 29.1583, when flight is conducted within the prescribed Category A profile/procedure, the H-V Diagram has no relevance*. However, omission of the H-V Diagram in the Limitation Section depends upon the Category A procedures being mandated in the RFM (which they are not).
* As Shawn indicates, there should be a note to the effect that the H-V Diagram can be ignored when applying the Category A procedure but I am not certain that it is always there - if not present, it is an oversight by the manufacturer and the regulator. It is not good enough "being taught" it has to be available within the RFM!
Most of the Part 29 helicopters that we are discussing here are normally flown in Performance Class 2 (and that applies to North America as well as Europe); that is achieved: in Europe - for operations with more than 9 passengers and/or flight over a hostile environment, by mandating Performance Class 2; and, in North America - for operations with more than 10 seats, by requiring the Category A WAT and enforcing the H-V Diagram, in the RFM.
Jim
Shawn Coyle
11th Aug 2014, 07:10
Jim:
As I thought. Thanks for clarifying (?) the situation a bit more. Most helicopters I know that have Cat A procedures have wording in the supplement that say the H-V chart can be avoided when using the Cat A profile.
“Thy will be done”!
I have been referred to a previous thread on this subject that started in 2004 and concluded in 2010. In that thread, I was optimistic that EASA had the resolve to remove, from Part 29, the requirement to have the H-V Diagram as a Limitation:
http://www.pprune.org/rotorheads/426597-multi-engine-helicopters-hv-curve-2.html#post5926055
I guess what has disappointed me about the current NPA is the approach taken, not just the content of the proposal - although it can be seen from this thread that it results from a lack of knowledge of the substance and intent of the certification and operational requirements/regulations – but the process of its provision.
As must now be clear to all who have taken the time to read and understand the intent of Part 29.1 (or accepted the central message of this thread), the two solutions (short term and long term) were the only ones that could have worked. This fact had been established for quite some time and, shortly after the formation of the working group (RMT .0132 & RMT .0515), an independent information paper was produced. This paper provided background to the changes to Part 29.1 that resulted from NPRM 80-25, the regulatory ‘trail’ for the H-V Diagram as a Limitation, and possible solutions. This was passed to EASA but they did not acknowledge or comment on it.
To the majority of the WG (one remained un-contactable and another supported the EASA position unquestioningly) the facts were incontrovertible and they made this clear by email. Projected meetings of the WG were cancelled and EASA (as they do when faced with opposition) continued with their proposal ‘in-house’. This was turned down by the (same) majority of the WG but EASA continued and produced NPA 2014-19. It is not clear that the proposal was seen by the WG before it was finalised and attached to a letter, dated 25th July, sent to the required regulatory committees and parties.
Interestingly, the letter states that “…once the regulatory changes are in effect, penetration of the H-V envelope when operating according to CAT.POL.H.305 approval can only be performed using helicopters with a Rotorcraft Flight Manual in compliance with the amended CS-29*. Operators should consider requiring the manufacturers to ensure such compliance for the specific helicopters.”
* That is, not in compliance with FAR 29.1.
Jim
HeliTester
12th Aug 2014, 04:15
JimL makes a very compelling argument for EASA OPS to mirror JAR-OPS-3. Because FAA has no operational performance requirements for helicopters (and likely won’t have in the foreseeable future), shouldn’t EASA’s short term goal be to only address the operational issue and not risk throwing CS-29 and FAR-29 out of harmonization, or invalidating existing operational performance rules after 28 October 2014. That JAR-OPS 3 has already made the necessary accommodation for Europe makes me wonder what can possibly be gained by reinventing the wheel. Helicopter operators and OEMs understand the existing rules and have provided the necessary operational procedures and supporting performance data to conform. Will recompiling the rule change the way and the payloads at which anyone actually operates? Could recompiling the rule cause the operators and OEMs to have to recompile their existing operational procedures and performance data? If so, at what cost? Will recompiling the rule make PC2 operations any safer than they are now?
The long term goal of removing the H-V diagram as a limitation via changing CS-29 (which must be an enormous rulemaking effort) could then be pursued with less disruption to the operators.
Thanks HeliTester - let's hope your sage words reach the ears of EASA.
With respect to Shawn's post on the H-V Diagram and Category A procedures; I was looking to see if there was guidance on what a statement to that effect might contain - I can't find any (and flight manuals that I have recently seen do not have any such statement). What I have found is guidance contained in AC 29.79(a)(9) with the following text:
(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.
(for those who know the rule numbers, 'Limiting Height-Speed Envelope' changed to 'Height-speed Envelope' after Amendment 29-38 and moved from 29.79 to 29.87; the guidance remained in place. This was quite logical as the H-V Diagram ceased to be a limitation at 29-21 when 29.1517 replaced the intent and limited the requirement only to Category A.)
Interestingly, immediately after this paragraph is another which impacts directly on the content of EASA NPA 2014-19 and, as shown already, further undermines the basis for their proposal:
(10) Rotorcraft certificated prior to Amendment 29-21 were required to have the resulting height-velocity diagram as an operating limitation. This limitation restricted opportunities when operating large rotorcraft in various utility applications. Subsequently, Amendment 29-21 allows, under certain conditions, the height-velocity diagram to be placed in the Flight Manual Performance Information Section instead of the Limitations Section. Specifically, the rotorcraft must be: (1) certificated for a maximum gross weight of 20,000 pounds or less; (2) configured with nine passenger seats or less; and (3) certificated in Category B. Testing must be completed with the aircraft at the maximum gross weight at sea level. For altitudes above sea level, the test aircraft must be at a weight no less than the highest weight the rotorcraft can hover out-of-ground-effect (OGE). Rotorcraft certificated prior to Amendment 29-21 can update their certification basis to take advantage of this provision.
The limitation clause (1) at 20,000 lbs does not accord with Part 29.1(d) unless an assumption is made that this clause actually mandates the build standard of Category A and only alleviates from the requirement to provide performance data and have the H-V Diagram as a Limitation. That has always been my reading of the intent of Part 29.1(d) and associated guidance.
Jim
Geoffersincornwall
15th Aug 2014, 07:38
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. :{
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.
(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.
(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
Geoffersincornwall
15th Aug 2014, 09:39
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.
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
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:
• 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.
* 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:
• 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;
• 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:
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
Geoffersincornwall
5th Sep 2014, 20:59
.... 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 :}
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
bpaggi
7th Sep 2014, 19:55
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.
Jim
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:
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.
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).
It is therefore concluded that certification in Category A does not imply that the Category A procedures have to be used!
Jim
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
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
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.
“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.”
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:
“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.”
Requiring compliance with Essential Requirement 4(a) of Annex IV:
“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.”
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:
“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:
CAT.POL.H.305 – operations without an assured safe forced landing capability;
CAT.POL.H.225 – helicopter operations to/from a public interest site.”
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.
Jim
bpaggi
10th Sep 2014, 12:04
"To raise new questions, new possibilities, to regard old problems from a new angle, requires creative imagination and marks real advance in science."
— Albert Einstein
:sad:
Geoffersincornwall
10th Sep 2014, 21:17
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. :confused:
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:
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:
(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.
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.
Garry M
11th Sep 2014, 10:52
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.
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
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:
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.
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:
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
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:
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.
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:
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
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:
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.
Jim
I feel I have now done as much as I can in providing the background and information to this debate. Unless there are comments put onto the thread, I will bring it up front at the end of October and before the EASA 27 November comment deadline.
Most of what has been posted on this thread has been gathered into a single document "Comment to EASA NPA 2014l-19" which can be found here:
https://www.dropbox.com/s/8nms9apezzn4siu/Response%20to%20NPA%202014-19.pdf?dl=0
If you intend to comment on the NPA, feel free to use the text in the document as you wish (without needing attribution).
At the end of the document (after the conclusions) you will find two Appendices: Appendix A - Equivalent Safety Finding on CS 29.1587(b)(6); and Appendix B - Appropriate Standards for Passenger Carriage.
Jim
I see that the CAA has just issued an Official Record Series 4 exemption to permit momentary flight within within the H-V avoid curve for operations with exposure. It also states in the preamble to the exemption that this will be mirrored by other States in Europe.
ORS4 No.1042: Helicopter Height Velocity Envelope - Requirement under Regulation (EC) No. 216/2008 that an Aircraft Must be Operated in Accordance with its Airworthiness Documentation | Publications | About the CAA (http://www.caa.co.uk/application.aspx?catid=33&pagetype=65&appid=11&mode=detail&id=6450)
Jim
As was indicated would be done, this is a reminder that the closing period for comments on NPA 2014-10 is within a couple of weeks:
Dear CRT User,
please note that NPA-2014-19 "Helicopter Height-Velocity (H-V) limitations" is now open for consultation on the EASA website.
To place comments, please use the automated Comment-Response Tool (CRT) available at:
http://hub.easa.europa.eu/crt/ (http://hub.easa.europa.eu/crt;)
The deadline for submission of comments is 27 Oct 2014.
Thank you for your interest in and contribution to the European Aviation Safety Agency's rulemaking activities.
Kind regards,
The EASA consultation team
look for NPA 2014-19 and comment in the usual way.
As indicated before, all points contained in this thread have been gathered into a single document which can be found here:
https://www.dropbox.com/s/8nms9apezzn4siu/Response%20to%20NPA%202014-19.pdf?dl=0
Any of the text from this document can be used in your comment without attribution.
Jim
gmrwiz
9th Nov 2015, 16:47
One year has expired since the closing period for comments on "NPA 2014-19
Helicopters H-V limitations"
Has a CRD been issued?
If not does anybody know the reason?
gmrwiz
7th Dec 2015, 16:57
I have asked EASA about the CRD to NPA 2014-19 and this is the answer:
Thank you for your email and your interest in the European Aviation Safety Agency’s rulemaking activities.
Further to your enquiry, please note that the CRD to NPA 2014-19 shall be issued in 2016/Q1 together with the related Executive Director Decision.
EASA clearly understood the comments that were reported on this thread; a proposal is contained in the amended Basic Regulation that is now going through due process.
Article 4 of Annex V 'AIRCRAFT PERFORMANCE AND OPERATING LIMITATIONS' mirrors the approach taken by the FAA in FAR 91.9(a) and (d). Thus it restores the status quo ante contained in JAR-OPS 3.005(b) and its associated Appendix - i.e. to permit momentary excursions through the limiting height velocity envelope (to an adequate level of safety).
Jim
gmrwiz
14th Feb 2016, 16:49
It seems at least strange that the Basic Regulation can be modified to accept the momentary penetration inside the H-V.
NPA 2014-19 was created to find a way to allow the penetration without violating the regulation itself. The NPA clearly states that:
“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”.
In addition para 2.1.3. Assessing the regulatory domains of NPA says:
“Operational Regulations cannot alleviate against airworthiness limitations, and neither operational regulations nor airworthiness limitations can alleviate against the Basic Regulation”.
I am very curious to see the way in which EASA has solved this problem.
The essential issue that had (has) to be addressed is that regulating (limiting) operations from within certification regulations results in unforeseen consequences.
The method suggested in NPA 2014-19 sought to change the basic premise of PART 29.1 - i.e. that all helicopters with more than 9 passenger seats should be operated for 'passenger transportation'; either through the utilisation of Category A procedures (29.1(c) - PC1), or by applying the HV Diagram as a Limitation and limiting the mass with the second segment climb performance (29.1(e) - PC2). Neither of these foresees the complexity of offshore operations or addresses, where permitted, Exposure.
States have, for some time, lived with this 'feature' of Part 29.1 in a similar way; when providing a regulation which requires compliance with the operating procedures and limitation of the Flight Manual, they provide the appropriate alleviation to the HV Limitation in its immediate vicinity.
Hence:
FAR 91.9(a) and FAR 91.9(d);
JAR-OPS 3.005(b) and Appendix 1 to JAR-OPS 3.005(b).
(Proposed) EASA Essential Requirements: Annex V Article 4.1 and 4.2:
4.1. 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.
4.2. Notwithstanding 4.1., for operations with helicopters a momentary flight through the limiting height velocity envelope may be permitted, provided that an adequate level of safety is ensured.
This returns the Essential Requirements to the status quo ante and achieves operational flexibility with the least disruption. It requires no amendment of EASA OPS which were drafted in the understanding that such a clause would be provided.
Jim
The EASA Comment Response Document (CRD) and opinion is now available:
https://easa.europa.eu/document-library/notices-of-proposed-amendment/npa-2014-19
It is extremely gratifying to see EASA accepting informed opinion. What a pity then that nugatory work could not have been avoided - saving time and money.
Jim
gmrwiz
9th Apr 2016, 16:30
The real pity is the NPA 2014 -19 itself.
The reason why it was written is clearly stated in Chapter 2 at 2.1.1 of the NPA:
“ Some aircraft flight manuals present HV envelope with variables for altitude and temperature included, allowing the pilots to insert the experienced values and thereby knowing whether or not operations will be performed inside the HV envelope. Other AFMs present conservative HV envelopes based on worst case scenarios. These are not allowing pilot calculations and are very limiting to operations”.
And the consequence of this poor HV definition (see page 10-24 of the NPA) is:
“ Avoiding the HV envelope requires reduction of landing or take-off masses for some helicopters types whilst others are prevented from operating.”
Therefore, to protect the operability of these helicopters, EASA decided to propose a change to Annex IV to regulation (EC) No 216/2008. The allowance to penetrate the HV envelope during take-off and landing from/to helideck is, in fact, included in the proposal of the European Commission for revision of Regulation No 216/2008 (see the EASA “Executive Director Decision 2016/005/R of 23 February 2016) .
This allowance, if introduced in the revised regulation No 216/2008, is:
a)unsafe because, when the HV really exists, an engine failure inside the HV envelope will be catastrophic
b)unfair with respect to those manufacturers who spent money and executed very dangerous test for defining a detailed HV envelope.
The right decision should have been to impose, to the manufacturers whose HFM did not provide a detailed HV charts, to define them and introduce in the Limitations section of the HFM.
In the USA FAR 91.9 d) gives similar alleviation but only when “ a safe ditching can be accomplished” and for specific helicopter’s configurations.
§91.9 Civil aircraft flight manual, marking, and placard requirements.
c)Any person taking off or landing a helicopter certificated under part 29 of this chapter at a heliport constructed over water may make such momentary flight as is necessary for takeoff or landing through the prohibited range of the limiting height-speed envelope established for the helicopter if that flight through the prohibited range takes place over water on which a safe ditching can be accomplished and if the helicopter is amphibious or is equipped with floats or other emergency flotation gear adequate to accomplish a safe emergency ditching on open water.
Unfortunately this is not the case for the operations in the North Sea that is considered “hostile environment” and, therefore, a safe ditching cannot be accomplished.
In addition to this HV topic, I think that time has arrived for imposing that helicopters operating from/to helideck in CAT operations must:
a)be Category A certified
b)fly the Category A procedures (PC1) for Take-off and Landing from/to helideck
c)be (these procedures) in the Normal and Emergency Procedures sections of the HFM approved by EASA
This because people, regularly flying from/to the oil rigs, are passengers at all the effects and, as such, must be protected with the highest safety standards offered by technology and airworthiness regulations.
The usual justification that the helideck environment is so peculiar that PC1 procedures cannot be executed is inconsistent. In fact the procedures can be, to some extent, adapted to the specific helideck. But the important element concerning the safety is that helicopter is to be operated at the mass derived from the HFM at the Weight, Altitude, Temperature (WAT) curves applicable to the procedure that the pilot wants to fly. And, sometimes, the mass allowed is lower than the MCTOM
It has to be noted that similar obligations already exists in the Air Ops regulation 965 /2012. Annex IV Section 2.
CAT.POL.H.310 (c)(2) for Take-Off and CAT.POL.H.325(c)(2) for landing, require to fly PC2 enhanced procedures for operations from/to helideck for any helicopter operated in hostile environment.
And these procedures, that should not be invented by the operators but EASA approved, correspond to PC1 because allow to survive an engine failure either in take-off or landing from/to a helideck, without ditching.
I am wondering if the National Aviation Authorities (NAA) are imposing them or are granting an exemption.
I say that because when these procedures were introduced by JAR-OPS 3, Amend 5, in July 2007, some NAA’s granted exemptions to the operators with the usual justification that the adoption of these procedures imposed, to some helicopter models, to operate at mass below the MCTOM.
I hope that the European Institutions are sensible to safety and reject the EASA’s request for penetrating the HV envelope.
Sometimes safety should prevail on business.
"I hope that the European Institutions are sensible to safety and reject the EASA’s request for penetrating the HV envelope.
Sometimes safety should prevail on business"
Sounds to me like you are the one interested in the business case rather than safety.
Safety abuse, playing on regulator's paranoia, for business purposes is insincere and cynical.
Where's the safety evidence for PC1? You are an AW salesman I guess? Or someone trying to pitch for a bigger budget?
Garry M
11th Apr 2016, 04:46
This is an obsession with yesterdays problems. The reliability of modern engines in a twin installation is such, that the risk during momentary exposure is practically negligible.There are plenty of other safety matters we should be worrying about. In regards to modern twins, this obsession with HV envelopes given the very specific conditions from which they are derived and are relevant, is beyond me.
Geoffersincornwall
11th Apr 2016, 09:24
.... yes some people seem to make mountains out of mole hills but there is a reason for that. If the regulations reflected the reality of our world then all would be fine but we, or at least some, have found out the hard way that when there is a disconnect between what we accept as the norm and what the rules have to say about it then it can result in the unjust prosecution of the pilot despite all above him giving tacit support to the institutional ignoring of what the rule book says.
A few months ago I pointed out that it is impossible for a night departure from an offshore platform to comply with the rules governing Vmini - but we all do it and will no doubt continue to do it. One day a pilot may end up in the dock because he broke that rule. We all know that night ops offshore would be crippled without the ability to launch off into the inky gloom so it is convenient for all to ignore it.
There is enough documentation supporting the concept off exposure and this should be enough to allow the pilot to escape censure in the event of a crash due to an engine failure at the critical moment - probably!
G :ok:
gmrwiz
11th Apr 2016, 10:26
I think that, instead of defaming me, you should expose your arguments.
And then why should I be an AW salesman and not Airbus or Bell or Sikorsky?
Take care.
Garry M
11th Apr 2016, 15:06
Geoffers.... my point alluded more to the matter of safety in response to this nonsense.
"I hope that the European Institutions are sensible to safety and reject the EASA’s request for penetrating the HV envelope"
Momentary exposure in a modern twin should be allowed... its sensible and the risk is negligible, particularly given the HV curve provides absolutely nothing in the way of absolutes.
Your point regarding a&%e covering is well noted :ok:
I think that, instead of defaming me, you should expose your arguments.
And then why should I be an AW salesman and not Airbus or Bell or Sikorsky?
Take care.
G Mr Wiz
I am sorry I don't mean to be rude to you, and I would be fascinated to known how a rational person being sincere can reach the conclusions you have. Normally it requires an abscence of any rational technical understanding (hence salesman). Also there is one manufacturer that has invested in extremely powerful machines capable of PC1 at MAUW. AW has a strong vested interest in this unfortunately illogical concept.
Margins
13th Apr 2016, 11:48
in this unfortunately illogical concept??????????????? What is illogical in this concept?
Margins
13th Apr 2016, 20:21
Examples of illogical in a sentence
It is illogical to think that things will change on their own.
<the illogical claim that playing basketball makes people taller because one sees so many tall players>
AnFI
Do you have any idea of what you are talking about?
I do
and I am in good company as Nick Lappos has often patiently explained
it's ok for someone that is not particularly technical to believe intuitively that the vast power reserve enabling no exposure at all sounds like a good idea but it really is a badge of ignorance
as far as i have been able to gather there once was a case of an engine failing during this critical phase, really not worth the lost payload potential etc etc
this is a discussion about the subtlties of the stichwork on the Emporer's clothes
Torquetalk
14th Apr 2016, 09:31
Do you have any idea of what you are talking about?
I do
No you don't.
And quasi-enlisting Nick Lappós to back up your bogus argumentation will not make YOUR false conclusions any more reasonable and convincing.
Power does matter. It isn't the only important factor, but it matters.
Anyone who has had to take off from a helideck with barely enough power AEO to do so, and done the same in an aircraft that flies like an elevator will know that.
There are other risks and some of them may be greater in terms of frequency (CFIT for example), but that isn't an argument for focusing on the other risk/s at the expense of one that can be improved/managed.
TT
megan
14th Apr 2016, 11:34
Momentary exposure in a modern twin should be allowed... its sensible and the risk is negligibleYou might not have that opinion if you have been there. I'm well aware of Nick's opinion that engine failures are not a thing to agonise over given their degree of occurrence. My experience is a failure at CDP on a platform TO, and the only thing that saved us was a good wind blowing. Looking at the graph Sikorsky later produced, with out the wind it would be a debate about how many survived the subsequent impact with the platform edge and impact with the sea possibly inverted.
Two years or so later in the same aircraft an engine failure at the commencement of a TO from a runway while Cat B. A failure 30 seconds later would have written off the aircraft. To me it doesn't measure up to the 10*-9 expected of our systems. Would any of you gladly hop on your 737, 320 etc if you knew a failure at V1 was going to end in a possible close encounter with objects in the over run ie having no guaranteed performance accountability?
Helicopters have enough failure scenarios to give you sleepless nights, tail rotors, gearboxes for example, why short change pax and crews by having exposure in an area that is so easily avoided. In saying so I recognise the impact of such an aircraft to operator costs etc.
Garry M
15th Apr 2016, 08:04
Megan
You have to look hard to find specific examples in the offshore world where an engine power loss during a critical phase of flight has been the primary cause of an accident in the recent past, even with older twins. It doesn't mean they haven't happened, nor does it diminish your experiences, its simply a reality.
I'm pleased you brought up the 737/A320 example as it helps make my point about reliability. For all the single engine performance those aircraft have, I can't think of an instance where any of the pilots I know flying those types, or anyone who has been a passenger on them, including me, has ever been in a situation that has required its use in an OEI situation. That's not to say they don't fail, they just fail rarely. Sadly modern airliners still spear into the ground for a whole host of other non engine related reasons. An aircraft's OEI capability gives me no comfort when the people in front run me into the berm at the end of the runway because they don't know how their airplane works (in the case of the Asiana 777 at SFO).
Don't get me wrong, I like flying machines that have plenty of OEI power, however I want regulators to be focusing their attentions on the big picture. As Geoffers rightly points out, we are operating in a regulatory system that no longer reflects our operational realities, perhaps hasn't for a long time. New aircraft have an exciting range of technologies that we can't remotely use to there full capabilities, primarily for regulatory reasons. I want regulators focused on rules that let me use those abilities to there maximum in ways that will really make a difference to safety. Getting bogged down about momentary exposure into a flight envelope that is so imprecise and inexact is a distraction.
Quite right Garry M
and can I just shoot down the 737 arguement right now:
aeroplanes are different
the 737 needs 2 engines because it does not land well enroute, in the wild, it needs a very special arrival surface
the 737 spends it's entire flight time exposed to catastrophic consequences if it lost all power, it's really not the same as the very brief exposure a helicopter might have during t/o
the maths is different for the 737 and the helicopter
there are several reasons why a helicopter may have to ditch, way way down on the list is engine failure during takeoff, so helicopters need to be able to ditch 'safely'
if you factor the chance of engine failure by the proportion of time spent transitioning through the HV curve on t/o you get an incredibly small number even when you do multiply by 2 (in a twin having twice the number of engines with which to have this failure), almost certainly not outweighing the more significant negative downsides of carrying such an excess in engine power
Megan I don't wish to diminish your beliefs founded in your extra ordinary experience but perhaps you could reflect on the statistical phenomenon of having 2 engine failures in 2 years on the same aircraft at this critical phase of flight. It is so statisticaly amazing as to suggest some other causual common factor to these events that almost could not happen otherwise
this is an old fashioned solution to a 'problem' that isn't 'the problem'
XV666
15th Apr 2016, 10:58
Quite right Garry M
and can I just shoot down the 737 arguement right now:
aeroplanes are different
the 737 needs 2 engines because it does not land well enroute, in the wild, it needs a very special arrival surface
the 737 spends it's entire flight time exposed to catastrophic consequences if it lost all power, it's really not the same as the very brief exposure a helicopter might have during t/o
the maths is different for the 737 and the helicopter
there are several reasons why a helicopter may have to ditch, way way down on the list is engine failure during takeoff, so helicopters need to be able to ditch 'safely'
if you factor the chance of engine failure by the proportion of time spent transitioning through the HV curve on t/o you get an incredibly small number even when you do multiply by 2 (in a twin having twice the number of engines with which to have this failure), almost certainly not outweighing the more significant negative downsides of carrying such an excess in engine power
Megan I don't wish to diminish your beliefs founded in your extra ordinary experience but perhaps you could reflect on the statistical phenomenon of having 2 engine failures in 2 years on the same aircraft at this critical phase of flight. It is so statisticaly amazing as to suggest some other causual common factor to these events that almost could not happen otherwise
this is an old fashioned solution to a 'problem' that isn't 'the problem'
More simplistic nonsense to try to bolster a hopeless continuing theme of a second engine being surplus to all requirements in the gospel according to AnFI.
Since the case of a 737 needing two engines because of en-route safety was cited, will AnFI please remind us how a single engine helicopter will avoid ditching after an engine failure whilst en-route to an offshore installation? Safely?
er heli
the 737 point was raised by xxx to argue against the exposure of the brief transit of the hv curve, it is not a valid arguement because the main reason why the 737 has 2 engines is for the enroute phase, where the consequence for the 737 of forced landing is so severe compared to the helicopter.
helicopters do not need to avoid ditching as 737s do, they just need to be able to ditch safely, a feat often demonstrated by twins and sometimes singles too.
ditching isn't bad, dying is
and could you try and avoid being so rude "More simplistic nonsense..."
personally (and for many others) carrying 2 engines is simplistic 1950's nonsense, but at least I have the civility to attempt to proffer logical points. PC12s do well on one engine and helicopters are even more suited to single engine than are aeroplanes (autorotation).
this discussion is more about the brief transit of the hv curve, and it is fairly clear that it is not a significant safety concern, as the salesman from AW was suggesting.
XV666
16th Apr 2016, 00:38
er heli
the 737 point was raised by xxx to argue against the exposure of the brief transit of the hv curve, it is not a valid arguement because the main reason why the 737 has 2 engines is for the enroute phase, where the consequence for the 737 of forced landing is so severe compared to the helicopter.
helicopters do not need to avoid ditching as 737s do, they just need to be able to ditch safely, a feat often demonstrated by twins and sometimes singles too.
ditching isn't bad, dying is
and could you try and avoid being so rude "More simplistic nonsense..."
personally (and for many others) carrying 2 engines is simplistic 1950's nonsense, but at least I have the civility to attempt to proffer logical points. PC12s do well on one engine and helicopters are even more suited to single engine than are aeroplanes (autorotation).
this discussion is more about the brief transit of the hv curve, and it is fairly clear that it is not a significant safety concern, as the salesman from AW was suggesting.
Rating these ideas as simplistic nonsense is stating a fact: it is not being rude.
The concept that "helicopters do not need to avoid ditching as 737s do, they just need to be able to ditch safely" is more of the same drum beating that AnFI has been bringing to the forum for way too long with his crusade to outlaw any more than one engine per helicopter. It is tedious, it is based on poor reasoning and is so predictable that it is bound to detract from any reasonable discussion where twin engine ops are raised on Rotorheads.
Avoiding ditching by having adequate reserve power in any aircraft is a duty owed to the paying passengers and to the crew. Quite how the bears would take to being told they are quite safe in AnFIs flawed logic when flying over a sea state 7 on a dark winter's day in the North Sea because it's OK as long as they can ditch safely, beggars the imagination.
heli - in AnFI's mind, his is a reasoned and coherent argument based purely on statistics - he has no experience of real-world ops in a twin where the number of times the crew is exposed to a dramatic outcome in the event of a SEF is far more than he can conceive.
The dismissal of ditching as an acceptable outcome is typical of someone who has spent little time over the water - especially in large sea states - and has never been dunker trained.
Lies, damn lies and statistics is a well worn phrase - I for one don't trust statistics as anything other than an analysis of what has happened rather than a predictor of what might happen.
gmrwiz
16th Apr 2016, 10:20
Dear AnFI,
you require not to be "rude" (see your response to Heli) but you insist to define me
"the salesman from AW".
I am not a salesman and the proof is that the point I raised is finding a considerable number of supporters. Are all salesmen?
Have a nice weekend.
Heli:
"is more of the same drum beating that AnFI has been bringing to the forum for way too long with his crusade to outlaw any more than one engine per helicopter. It is tedious, it is based on poor reasoning and is so predictable that it is bound to detract from any reasonable discussion where twin engine ops are raised on Rotorheads."
There's no material in there. The mods seem to accept this rude approach provided it is on the twin engine side of the 'discussion'.
As for your point about fare paying passengers and avoiding ditching etc, that is a different point, 2 engines in the cruise over a hostile surface when they are so poor at ditching has a natural attraction, especially in the NoTech mind of the 'bears'. (and I don't know, if you gave them the choice of the heli that can land safely on the water and the one that can't (but theoretically won't need to), maybe they would choose the safer one?)
The excess power to avoid exposure during t/o is a different discussion. There is simply no factual safety case for it AFAIK. It's hypothetical armchair layperson stuff, the kind of hypothetical that Crab doesn't like.
These NS machines seem to have a fairly poor record considering that they are flying the simplest type of flight (mostly autopilot cruise), loaded with safety aids, 2 commercial pilots, huge training / checking.
Crab: "his (AnFi) is a reasoned and coherent argument based purely on statistics" thanks
Crab: "The dismissal of ditching as an acceptable outcome is typical of someone who has spent little time over the water - especially in large sea states - and has never been dunker trained." I note that you are rightly not suggesting that is the case with me, merely that others also share this view. Obviously ditching is an acceptable outcome IMO when one's gearbox is on the way out for example, you don't think so?
(maybe I don't have oversea flying experience, ditching experience nor dunker training. Or maybe I do, but the logic is the point, not a discussion of your relatively limited experience)
If the risk of ditching were reduced to an acceptable level then twins would not need to waste payload on floats. In fact they ditch often enough to need to be good at it. (maybe better than they are)
Crab: "I for one don't trust statistics as anything other than an analysis of what has happened rather than a predictor of what might happen. " .... and Ronnie Regan used to consult astrologers but it's not a really sound way to design aircraft is it.:confused:
gmrwiz, I am sorry I really genuinely don't mean to be rude and I'd love to engage respectfully with you on the issues. As for your suggestion that being an AW salesman is an insult, I think that AW salesmen might be offended by that, AW salesmen have done a superb job and have been very succesful. I was just concerned that you were trying to suggest that prohibiting exposure during t/o had an obvious safety benefit, when it is the opinion of some of the most technically aware on this forum that it does not. (although it is not obvious, there are increased risks consequent from eliminating that one)
The reasoning requires more space than this forum allows but an example of one point is:
If a helicopter can be operated without exposure with 2 pax, but would be exposed with 6 pax. Then is it safer to run 3 flights to move the 6 pax or one flight? One operation has exposure and the other has 3 times all the other many risks (which are also greater riskes than engine failure anyway). Obviously the t/o engine expose case is safer.
Don't expect to hear a logical reasoned counter arguement to this, instead watch the insults roll in :{
Senior Pilot
16th Apr 2016, 23:00
There's no material in there. The mods seem to accept this rude approach provided it is on the twin engine side of the 'discussion'.
Since you have brought me into this, do not (and I mean this) assert your interpretation of discussion on this forum as yet another reason to berate me for not taking your side. Should posts breach the T&C then they will be moderated; this has not happened in this thread. Disagreeing with you is not automatically an insult nor rude no more than your manner of disagreeing with others.
And I strongly suggest that when quoting other members then you include all their post without cherry picking and excluding such defining precursors as were used by crab@, but conveniently left out by you to make it appear that his statements in some way added veracity to your theories.
megan
17th Apr 2016, 04:02
You have to look hard to find specific examples in the offshore world where an engine power loss during a critical phase of flight has been the primary cause of an accident in the recent pastIn the case of my failure at CDP, a highly credentialed person had this to sayIt would appear that you were luckynot to hit the deck edge. I don't want to live my life on the rationale that I, crew and pax get to survive by being lucky.
SP thank you for the feedback, FWIW I say again here (as elsewhere) I think your moderation is excellent, and would not dream of 'berating you'. I thank you in advance for helping me to try and balance the discussion. Quite right about selectivity with Crab, but I didn't detect anything there except slur (that incidentally you know not to be true, and I was under the impression that there were more than one mod?)
I do try to stick to the point. Facts and well structured logic should work.
megan (thank you for debating the issue) indeed it is extra ordinary, and I can understand how you feel, but of course we have no choice but to live in a world of probability, the best we can do is optimise that for you.
So in the example below of moving the 6pax which of the 2 options would you be happiest with?
3 trips with 2 pax or 1 'exposed t/o' trip with the 6?
please could you/would you send me a link to the report on that incident as it is obviously an important 'data point'.
" the main reason why the 737 has 2 engines is for the enroute phase"
So that's what I've been doing wrong all these years :)
phil
wiggy
17th Apr 2016, 07:20
If as a "plank" I may stop lurking for a second:
the main reason why the 737 has 2 engines is for the enroute phase"
I'm bemused as well, there's no doubt most airliners spend the majority of their moving life in the cruise but I wouldn't by extension say that's the reason for 2 engines - I rather suspect that somebody's logic is flawed here.
AFAIK on the large commercial fixed wing side of things multiple engines are required to ensure a safe outcome for the flight in the event of an single engine failure. The regs don't specify a specific flight phase...the principle covers all stages of flight, including take-off - where despite all the 10 to the 9 stuff engine failures do still happen.
I don't know about you rotary guys but personally if I'm going to lose a donk (or even both) on a twin I'd actually much rather take the failure in the cruise rather than just after lift off with perhaps inhospitable terrain/built up area ahead...
Anyhow that's how I see it from my world, two engines is good for me and my passengers, etc, back to lurking..
I don't know about you rotary guys but personally if I'm going to lose a donk (or even both) on a twin I'd actually much rather take the failure in the cruise rather than just after lift off with perhaps inhospitable terrain/built up area ahead... wiggy - no need to lurk - your views are exactly aligned with pretty much every pilot here with one clear exception..........
AnFi - this .... and Ronnie Regan used to consult astrologers but it's not a really sound way to design aircraft is it. must be your best, most irrelevant and utterly pointless reply so far on this or any other thread - well done, keep taking the medication.
the thread is supposed to be about exposure for hv curve transit
not much material coming back on that?
the clear question is:
in the example below, moving the 6pax, which of the 2 options would you be happiest with?
3 trips with 2 pax or 1 'exposed t/o' trip with all 6?
what is your view on that wiggy, heli1, megan, crab ?
wiggy the maths isn't really the same for aeroplanes
in helicopters the engines have a common gearbox and common power delivery unlike the aeroplane
there are also more critical dynamic systems
the helicopter is able to land with significantly less kinetic energy than the 737
etc etc
I accept what heli1 says this is a simplistic argument and factors like the irrational beliefs of pax are material
crab I was merely pointing out that your dismissal of stats as damn lies etc (although understandable) is one of the material complexities of the issue ie "I don't care what the facts are I just know I feel better ... etc"
I don't think I am being rude to you am I?
There are exciting possibilities with asymetric engines for instance, having emergency power for just 2minutes, would give you the advantages of a single with the 'easy landing option' of spending 2 (or maybe 5?) minutes landing gently in the water (in the case of the NS). AB have some thoughts on this concept. Rules should be about the outcome required etc
megan
18th Apr 2016, 02:15
When I gave up the business over a decade ago there were only two classifications, Cat A & B, none of the new Performance 1 etc.
The take off procedure laid down in our Ops Manual of the time implied guaranteed success from a failure at CDP on a platform take off, and this was backed up with sim training at West Palm, where no matter what numbers were dialled in, you were always able to fly away, providing you didn't do something absolutely stupid. But it took a conversation with an expert a few days ago to open my eyes that our procedure did not guarantee success, and his analysis was that the failure occurred a couple of seconds after CDP, which agreed with the copilots observation. Had it occurred at CDP, which was my impression, we would have impacted the deck edge. Who can guess the result of a helo freefalling 100 feet into the water, would we have incurred eleven fatalities? The industry would have sat up and took notice had that occurred I bet.
§29.63 Takeoff: Category B.
The horizontal distance required to take off and climb over a 50-foot obstacle must be established with the most unfavorable center of gravity. The takeoff may be begun in any manner if—
(a) The takeoff surface is defined;
(b) Adequate safeguards are maintained to ensure proper center of gravity and control positions; and
(c) A landing can be made safely at any point along the flight path if an engine fails.
Mention is made of momentary exposure in posts, how does that align with (c) above?
Or is it a case of regulations not keeping up with ingrained industry practices, as suggested in some posts?
one is aircraft certification and the other is operating manner
'safe landing' does not mean 'does not crash'
which hypothetical case do you prefer for the 6 pax to be moved? - exposure can be safer
JimL is the expert at this field, nobody else understands it as he does. The mess he is trying to sort is made by people that dont understand it.
Of course if a 'safe profile' is flown then the HV curve should not apply, since there is 'accountability', but there is the question of interpretation between at least the USA, EU, ICAO, and the analysis of risk has historically been a little dodgy (eg you can't meaningfully square 1x10^-5) and seems to make you and crab distrustful of the stats
best wishes
bpaggi
18th Apr 2016, 12:39
Or is it a case of regulations not keeping up with ingrained industry practices, as suggested in some posts?
Operations over oil rigs under Category B envelope do not protect from engine failures during the takeoff and landing phase even if you operate outside of the H-V curve. This is because in all the RFMs, the H-V envelope has been determined for a complete different type of surface and there is no possibility to determine a H-V envelope on this type of surface.
The NPA has been issued only to try to fix an operational issue through a bureaucratic approach and the possible revision of the basic regulation, if any, will never add any safety to these kind of operations.
gmrwiz
18th Apr 2016, 18:37
AnFI
in the example below, moving the 6pax, which of the 2 options would you be happiest with?
3 trips with 2 pax or 1 'exposed t/o' trip with all 6?
I think that this case is not appropriate. A 6 passengers helicopter is a Part 27 and HV is performance information.
More appropriate is the case of a 20 passengers helicopter:
Carrying 20 pax require exposure while with 15 pax you can fly PC1 procedure . Which one do you choose? I have no doubt : 15 pax.
g..wiz great answer you are spot on
are you familiar with George Bernard Shaw asking a Lady on a train if she would 'sleep with him' for a hundred million pounds (inflation adjusted)? she said "yes", so then he said (to cut a long story short) that he had established that she was a whore but now they were just haggling about the price!
In the same way we should quantify where the threshold is. It certainly is not 20 to 1, you say it is 20 to 15 ... the threshold is somewhere, and a little logic and maths can help us find 'the right answer', it is not an absolute.
We are smart and we should apply some science and logic, not just knee jerk reactions and gut-feel We can do better than that.
Maybe exposure, maybe even a B3 with 2 pax on board, floats, emersion suits, modern avionics, sliding doors and dingies is justifiable? Maybe? Many more pilots employed for starters.
Exposure can be right, there's a level at which it works.
(despite what the AW salesman(?) bpaggi says)
thanks for answering the point, much respect, and i don't mean to be rude
gmrwiz
19th Apr 2016, 07:42
AnFi, Congratulations. You discovered another AW salesman. Why don't you apply for a job with the Mossad?
212man
19th Apr 2016, 08:10
AnFi, Congratulations. You discovered another AW salesman. Why don't you apply for a job with the Mossad?
Pretty sure he has nothing to do with sales - his user-name would suggest he's in their Flight Test dept! So, not so remarkable a discovery at all:ok:
https://www.ainonline.com/sites/default/files/pdf/esarotorcraftsymposium2015.pdf
bpaggi
19th Apr 2016, 09:12
AnFI please stop labeling people, if you do not have enough technical arguments just leave the thread.
Mr Paggi
A) you are an AW employee !
B) you are a salesman ! (selling HOGEFAP (Hover Out of Ground Effect Fly-Away Performance)
C) your technical arguments are susspect (selling HOGEFAP) because they are likely to support the interests of your employer
D) there is nothing wrong with my technical understanding, thank you.
Itally has a very fine heritage of design (Savoia, Macchi, Piagio, Ferarri etc etc, way groovier that the Germans or French ever managed etc how can you tollerate allowing that heritage to be sold out to bureaucrats, wtf do they know about design? You know better, or at least you should!)
Why don't you honestly answer the question about 'exposure' ?
It CAN be safer, true?
What's your answer in the example? If you want then replace 6,1,3,2 with w,y.x and z and then say where you think the safety threshold is? but the point is it IS somewhere, right?
Perhaps even a B3 with 2 pax, 2 dingies and floats and 2 sliding doors would be safer?
More pilot employed also.
We can't have aviation design poilcy made from commercial interest nor amateur guesswork, unless you want protectionism?
Don't disparage my technical credentials if you don't know what they are pls.
you have been
AnFi'd
gmrwiz
19th Apr 2016, 19:39
AnFI,
about your
In the same way we should quantify where the threshold is. It certainly is not 20 to 1, you say it is 20 to 15 ... the threshold is somewhere, and a little logic and maths can help us find 'the right answer', it is not an absolute.
I have to admit that you are very clever to ridicule my thoughts.
So let me explain the rationale behind my example
15 Pax vs 20 shows that flying PC1 with a medium helicopters, like those operated in the North Sea, does not increase significantly the number of flights: 4 flights instead of 3 for moving 60 pax. The increment is 1 over 3 equal to 33%.
While in your example, 2 pax vs 6, applicable to a B206, the increment is 2 flights over 1 equal to 200%.
So I was not playing with numbers but only trying to demonstrate that
"no exposure" does not increase dramatically the operational costs if you compare with the costs , in human life and economic, associated with a potential accident.
Gee Mr Wizz
I definately mean not disrespect, quite the opposite infact, I have a lot of respect for you, like wise for Paggi really, although we have to be aware that it is difficult for him to be objective since his job is to promote a particular technical solution.
A serious understanding of these concepts is vital.
The point about the 200% against the 33% is we do accept that there is a number. Now we have to look at whether that number is important or unimportant.
I would like to suggest that it is more important than is obvious.
We could simply take the proportion of the total losses that are caused by engines and divide by the total losses.
If this number were, say then 50% then your 33% deal would be worth it.
If that number is 5% then it is not worth it. We have then made it more dangerous in the misguided attempt to make it safer.
It is an example of too much emphasis on egines, at the expense of weight/payload that would be available to spend on higher yielding safety features. (like fuel maybe)
AnFI - so far your total contribution to this thread (as in so many others) is to get poeple's backs up and make random statements to try and enforce your rather random opinion whilst trying to use pseudo-science to give validity to your viewpoints.
You will only be happy when everyone is flying around in single-engine aircraft happily ignoring the constant exposure because, according to your statistical analysis, engine failures don't count as a risk because they happen so infrequently.
If the great and good (and far more technically knowledgable) of the aviation world shared your views then we wouldn't have multi-engined aircraft................but they don't!
Now be a good troll and bother someone else since you clearly don't have anything of value to add.
Crab I cannot tell if you are making a technical point.
Are you in favour of exposure or not?
So far I understand that you don't like statistics, you disagree with me (on what specific point we don't know), and instead of actually making a point you'd like to be rude to me. If you carry on being rude to me then I am sure that I'll be banned for it, you have been warned.
You seem to be (deliberately?) misconstruing what I am saying also:
"according to your statistical analysis, engine failures don't count as a risk because they happen so infrequently."
That isn't even nearly what I said. ( the simple version of what I said is if you eliminate a small risk at the expense of creating a larger one then you have not reduced the risk but increased it)
Do you have anything to contribute beyond your attacks on me?
AnFI - I don't think anyone deliberately misconstrues what you say - it is just that you are not very good at putting your point (which apart from single engine is better than twin we don't really know) across.
Which exposure do you mean? Flying across the sea on one engine, temporarily entering the H-V curve in a twin, ditching a 737???
I know I flew defensively in a single and had to constantly consider the OEI performance in a twin in the low speed environment and there were some situations where an engine failure would have been very unpleasant whether in a single or a twin - but that was all in military ops where the risk/ reward balance is different.
if you can remove some risk relatively easily then you should do it - therefore flying pax in a SE helo is always going to be more risky (in terms of outcome following a single engine failure) than it will be in a twin.
As ever, you love to tease and play games with what your experience is or isn't - it's rather tiresome and you have no credibility on this forum when you do so - don't be surprised if people are rude to you.
Crab "Which exposure do you mean? Flying across the sea on one engine, temporarily entering the H-V curve in a twin, ditching a 737???"
We are talking about "temporarily entering the H-V curve in a twin", I guess you actually agree with me but find that difficult?
Did you ever ditch?
Did you ever have any engine failure? (how did that work out for you?)
HeliTester
21st Apr 2016, 21:24
Before it got hijacked, this thread featured relevant discussion about an important topic.
AnFi:We are talking about "temporarily entering the H-V curve in a twin", I guess you actually agree with me but find that difficult?
I am trying to keep it on track.
JimL, Nick Lappos and I beleive that Exposure (in the sense above, being discussed) makes sense.
Mr WIz, Mr Paggi do not agree.
It is not clear where Crab stands on this issue.
I have given a pretty clear example of how this type of exposure can be safer
HT I am guessing that you are in the HOGEFAP camp?
We are talking about "temporarily entering the H-V curve in a twin", I guess you actually agree with me but find that difficult? No, I don't, not when carrying pax - it is duty of care and you are totally responsible for their safety.
This discussion is about poor legislation and certification vs the need to get the job done but the overriding argument has to be about safety.
As has been asked before - would you travel or put your wife and kids on an aircraft if you knew that an engine failure at a critical stage of flight would result in a hazardous visit to the scenery? Or would you rather that the certification and operating procedures ensured a safe landing or safe continued flight with no period (however short) of extra risk?
At TDP on an aircraft that needs penetration into the H-V curve, you are working the engines at MTOP - and if one is going to fail, that is the most likely time.
Yes I have had an engine failure in a twin but not at a critical stage of flight so no drama - would have been much more exciting in a single though.
gmrwiz
22nd Apr 2016, 08:12
crab, I can't agree more with your last post. Very well written and very clear. Congratulations.
Hughes500
22nd Apr 2016, 09:15
This is getting quite amusing as a bystander here , but to put some sanity into the HV argument who can answer the following probability questions from actual information
1. chances of any engine failing at any point in the flight regime
2. chances of engine failing within HV curve
3. chances of a mechanical failure at any point
4. chances of mechanical failure within HV curve
5. chances of pilot error within any point of flight regime
6. chances of pilot error within HV curve
Once we know this information a sensible risk assessment can be made so ANFi can argue his point with actual information
Yes there is a risk to everything we do but ......
Before I get shot down too much I have had an engine failure at 100 ft 30 kts coming into land. Have had miss running engines requiring a landing 3 times in 7500 hours
I have taught my daughter to fly and yes into the H/v curve you have to to get a PPL. Flown my wife in and out of the H/V curve in both singles and twins, as i believe the risk of engine quitting is remote.
Yes you can argue what you want that a twin is better than a single but you could also argue what happens if the combining gearbox decides to take a break ??? Could have 3 engines doesn't make any difference. Again what is the probability of that.
It is all about weighing up risk and everyone has a different view. I would suggest that the pilot is the biggest risk not the machine.
Incoming
Since my views with respect to 'Exposure' have been referred to, it is probably best that they be accurately expressed. Rather than provide a lengthy monologue, anyone who is interested in them can read them in soon to be published RAeS Discussion Paper shown in draft here:
https://www.dropbox.com/s/vq36s43on3j624f/Setting%20Appropriate%20Levels%20of%20Safety%20for%20Operati ons%20with%20Exposure%20%28extended%29.pdf?dl=0
The link to the RAeS paper will be provided when it is published.
Two other issues that need clarification are:
Contrary to what has been stated, an engine failure within the Category B profile does require a landing within the serviceability limits of the helicopter in the take-off and landing profiles.
The scope of the H/V diagram was explained earlier in the thread in post 29 and was:
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.
Jim
Thanks for that link Jim - I think every pilot should be made to read that document.
JimL:
Thank you so much for that, it's exactly what this debate needs, a framework for constructive discussion.
Crab:
I am grateful to you for answering the point.
And hopefully this answer to your questions will help you look at it in a different way(?):
Q1 "would you travel or put your wife and kids on an aircraft if you knew that an engine failure at a critical stage of flight would result in a hazardous visit to the scenery?"
Yes definately, and most certainly if the overall flight risk were less (obviously?).
Eg:
I would put them in a PC12.
I would not let them get in the 1970's Barron (which is mandated for PT, due to the type of logic you have used)
Q2: "Or would you rather that the certification and operating procedures ensured a safe landing or safe continued flight with no period (however short) of extra risk?"
No I would not like them to be subject, without a choice, to the increased risk associated with this approach. 2 Pilots, trained to a tickbox level, checked according to the CAA required level of competance, bored and ignorant, flying a 'look how bug my chopper is' ego trip machine. So no, the certification process, provides no confidence, hampers talented designers, creates absurd committee designed aircraft, with ludicrous gearboxes, fuel systems that even talented ex military pilots can't operate (apparently). So YES I'd be happy for them to be exposed to (the miniscule) engine risk in exchange for not having to suffer the additional risks disproportionately encountered in the (misguided) attempt to eliminate that obscure emotional risk.
I am yet to read all of JimLs paper but the probability analysis is at least a sound way to look at it. We just have to convince crab that a little probability theory is not as evil as he thinks, we are out of the dark ages aren't we?
There is a REALLY great way to look at risk. It is called the MICROMORT.
It is a unit of exposure to risk of 1:10^6 (ie 10^-6) of death.
It helps put in context the risks one takes and to get things into a rational perspective.
1 micromort is encountered when travelling by car 200 miles, motorbike 6 miles.
Being exposed to 9 seconds of 'exposure' adds about 0.02 of a micromort, whereas in the UK we face 0.8 micromorts per normal day (for non-natural death).
We do need protection from the logic that disregards science and fills people's heads with superstition. "Just imagine how terrible it would be if the engine quit just at this or that special moment, we must do something about it, we have a duty of care"
And if this (slightly mean spirited) mechanism were used then we could get it in perspective also:
"Value of a Statistical Life (VSL) - or Value for Preventing a Fatality (VPF) - to evaluate the cost-effectiveness of expenditure on safeguards."
A reduction in risk from one (already a very very low proportion of accidents) cause cannot justify increased risks in the other areas that are a much higher proportion of the accident causes.
(Crab, just curiousity, but for your one engine failure, what exact phase of flight were you in, cruise... over a rough sea at night? or a calm sea of about 10deg C in daytime? It's likely to have been the legendary 'dark and stormy night' in your old line of work i imagine)
Micromorts - FFS - more utterly pointless statistical analysis but I guess it is the sort of thing bean-counters love to bits.
2 Pilots, trained to a tickbox level, checked according to the CAA required level of competance, bored and ignorant, flying a 'look how bug my chopper is' ego trip machine. So no, the certification process, provides no confidence, hampers talented designers, creates absurd committee designed aircraft, with ludicrous gearboxes, fuel systems that even talented ex military pilots can't operate (apparently). if this is the opinion you have of your fellow professionals in the aviation business, maybe you should look elsewhere for employment.
My engine failure - which isn't relevant since it was in a military aircraft not subject to any civil performance criteria and not flying CAT - was a 100' crossing the airfield at RAF Valley for dispersal with a student in the RHS. No dramas and a safe running landing to the nearest taxiway.
Back to the wife and kids - if you put them as fare-paying pax into an aircraft that then crashed because additional exposure was experienced and the engine failed at a critical point - would you sue?
Hughes500
24th Apr 2016, 19:23
Crab
Just s thought for you the NTSB is now very concerned that pilots of PT planks are now losing their skills and suffer from immense boredom monitoring instruments. The manufacturers are trying to make the ac fly itself and keep pilot out of the loop, well that is airbus view. Boing view is that the pilot is part of the aircraft.So perhaps AnFi's 2 pilots just ticking things off is right !!!!!!! Don't shoot the messenger here !
Crab "Back to the wife and kids - if you put them as fare-paying pax into an aircraft that then crashed because additional exposure was experienced and the engine failed at a critical point - would you sue?"
No I don't think so. I think I would focus on the constructive future. I think I would be happier to live in a world where I am not forced into the irrational by the paranoid for the sake of irrelevant risk overreaction. You do realise that the twin loss rates have been fairly high over the last 10 years? The problems don't seem to be engines.
Your engine fail, fair enough, and in a single you would have been fine also I guess, with at least half the chance of it occuring at all.
Statistics help people make rational decisions, despite irrational knee jerk desire to respond to distorted impression of risk. Micromorts are a clear way to convey rationality to people who are challenged otherwise.
H5 thanks for the support
Statistics help people make rational decisions, despite irrational knee jerk desire to respond to distorted impression of risk. Micromorts are a clear way to convey rationality to people who are challenged otherwise. No, the big problem with statistics and probability is that they tell you how often something might happen not when it will happen - that is why you can have 1000's of flying hours with no fatals and then 2 on the same day.
It doesn't make for good safety planning, especially in terms of customer expectation, it just gives the bean counters a means to quantify the cost of a life.
Yes, CFIT is a bigger killer than engine failure but the corrections to the 2 issues should run in parallel, not in competition.
Hughes - you are absolutely right, skill-fade due to automation-reliance is very real in the FW world and is spreading into the RW world. I'm an old-fashioned boy (perhaps dinosaur) and rather believe if you have a pilot in the cockpit, he should be capable of flying the aircraft really well.
ShyTorque
25th Apr 2016, 07:44
Having trained on single engined aircraft (FW and RW), flown them as an instructor and wrt helicopters, operationally, I have since flown twins for quite a long time.
I maintain the view that I'd rather have a well equipped single than a poorly equipped twin.
However, the argument for and against SE isn't just about the likelihood or not of engine failure. It's about duplication of other systems, such as electrical generators, especially with regard to IFR operations.
I have flown in IMC in both single engines fixed and rotary wing aircraft (trained to do so and done quite legally) but i do look back and think that I'm very glad not to have to do it now.
Shy:
"I maintain the view that I'd rather have a well equipped single than a poorly equipped twin."
Quite right
"However, the argument for and against SE isn't just about the likelihood or not of engine failure. It's about duplication of other systems, such as electrical generators, especially with regard to IFR operations."
Agree on the other systems, so they should not be linked to number of engines, let singles duplicate if that is appropriate. Anyway duplication does not equate to more reliable, (the opposite often, magnetos are a classic example)
"I have flown in IMC in both single engines fixed and rotary wing aircraft (trained to do so and done quite legally) but i do look back and think that I'm very glad not to have to do it now." Sure, but a B3 now does not have a significant downside from only having one engine, but does have a significant downside in not being more capable wrt equipment (esp legality of IMC equipment)
Crab "skill-fade due to automation-reliance is very real in the FW world and is spreading into the RW world. I'm an old-fashioned boy (perhaps dinosaur) and rather believe if you have a pilot in the cockpit, he should be capable of flying the aircraft really well. " I am completely with you on that one, although there are significant operators who think that there's not enough understanding of the automatics either.
As for your views on statistics and probability I don't think you have logic on your side on that one.
The numbers in my (oversimplified) example surely illustrate that small point (?)
XV666
25th Apr 2016, 09:17
You do realise that the twin loss rates have been fairly high over the last 10 years? The problems don't seem to be engines.
But what about the helicopters (and fixed wing) that have made it safely back because they had a spare engine to keep them going after a failure?
The constant banging on by AnFI about a second engine not being needed seems to conveniently ignore the realities of the complete flight regime, and I notice that we still don't have a response from him about how a safe ditching can be achieved following a SE helicopter engine failure over a sea state 6, as he previously posted.
No, I am not an Agusta salesman.
AnFI - look at it this way - which helicopters are written off or badly damaged the most? Oh, that will be single engined ones then.
Why? because they are used for training and some of that training is touch-down autos (EOLs). Why? because the effect of a single engine failure in a single is usually much worse than in a twin so dealing with that becomes quite high up in the priority list.
Why bother? according to your viewpoint and 'statistics' you are as safe in a single yet AFAIK all authorities around the world require that EOL skill (even if the examiners might not be up to it any more).
The British military (and others) are going to twin-only training, even for basic helicopter trg, all Police and AA in UK are twins, SAR is in twins - even the Queen flys in a twin.
So, has everyone else in the world got it wrong and you are the true voice of reason???
Discuss:ok:
Crab:
"The British military (and others) are going to twin-only training, even for basic helicopter trg, all Police and AA in UK are twins, SAR is in twins - even the Queen flys in a twin.
So, has everyone else in the world got it wrong and you are the true voice of reason???
Discusshttp://cdn.pprune.org/images/smilies/thumbs.gif"
It is not the most sensitive time for me to put my views, as I imagine is very obvious with these recent events.
I think the excessive emphasis on engine failure is not sound.
Engine redundancy comes at a price that needs to be factored in and not ignored.
It was referred to by H500:
"Yes you can argue what you want that a twin is better than a single but you could also argue what happens if the combining gearbox decides to take a break ??? Could have 3 engines doesn't make any difference. Again what is the probability of that.
It is all about weighing up risk and everyone has a different view. I would suggest that the pilot is the biggest risk not the machine."
gmrwiz
20th Dec 2016, 08:08
Has the revision to the EASA Basic Regulation 216/008 allowing, in Annex IV, the penetration in the H-V region been issued?