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biz-buz
25th Aug 2009, 21:26
I am in the middle of a major discussion with EASA, the DGAC and Eurocopter regarding the compliance of the AS355 F and N series with the FAR 27 and FAR 29 criteria for Category A Certification equivalence. A real farce. :mad:

Despite the fact that there are a large number of aircraft in EASA airspace which currently operate to these criteria, nobody can produce any official DGAC or CAA for that matter, certificate which clearly states that with the retrofit parts installed, the aircraft complies with the Engine Isolation requirements. What a joke! :ugh:

I thought perhaps that amongst the wealth of professional operators present, somebody might have a copy of an official document which clearly states that if fitted with the necessary retrofit bits, the AS355 F and N series comply and so have Cat A equivalence. To further confuse the situation EASA actually refer to the AS355 in the latest draft of NPA Ops 38 F.4.7, see page 9 of 203.

It is also worth noting:
The AS355 NP is now certified (See EASA site TCDS) as being Cat A equivalent.
The F, N and NP apart from the engines and minor transmission mods, are identical, except that the NP has the retrofit bits installed on the assembly line!

I would be most grateful for any documents relating to this Cat A equivalence question , or any comments from any interested parties who currently operate these aircraft what they plan to do after 2010.:ok:

JimL
26th Aug 2009, 06:42
It is not clear what certificate might be issued. The information that is provided in ACJ OPS 3.480(a)(1) and (a)(2) paragraph 2. depends upon an assessment of 'engine isolation' that is described in AC 27 MG 3 - the preamble to which is shown below:

AC 27 MG 3. DEFINITION OF ENGINE ISOLATION FEATURES AS APPLIED TO §§ 27.79(b)(2), 27.141(b)(1), and 27.143(d)(1) (Amendment 27-19).

a. Explanation.

(1) Each of the cited performance and flight characteristic sections of Part 27 mention multiengine rotorcraft meeting transport Category A engine isolation requirements or refer to engine isolation features which ensure continued operation of the remaining engine. Unlike normal category fixed-wing (Part 23 § 23.903(c)) and the transport category fixed-wind and rotorcraft regulations, Part 27 does not provide a general engine isolation rule to make this determination.

(2) While it is clear that Part 27 does not require complete engine isolation, if credit for this feature is claimed (i.e., sudden complete engine power failure is not considered in showing compliance with the cited section), criteria must be established to allow a satisfactory isolation assessment.

(3) An approach which the FAA/AUTHORITY would find acceptable in making a Part 27 engine isolation determination is given. The FAA/AUTHORITY logic for establishing this criteria is also presented.
Jim

biz-buz
26th Aug 2009, 08:16
Jim,

Thank you for your reply.

I appreciate the legislation is not overly precise which is why I wished to avoid any discussion as to whether the AS355 F or N, in anybody's opinion, fulfilled the criteria or not. This is a separate discussion and one which will hopefully take place in early September between Eurocopter and EASA. In any case it is the responsibility of the TC holder to fight this particular battle, EASA will discuss but not debate it with me!

My point is that these aircraft have been operating with CAT A equivalence for years now, yet suddenly there is no tangible, documentary proof that they have CAT A equivalence. Due to the time gap (1980's), nobody seems to have any original documentation, from any of the major European Aviation Authorities, which supports this claim. The Flight Manual certainly has the required tables and instructions, there are also various Service Bulletins (26-01, 65-03), Service Letter (1779-00-06) and documents from Eurocopter which confirm this is the case, but nothing from the DGAC or anybody else which confirms this proposition.

I am currently trying to encourage Eurocopter and EASA to accept to work backwards from the recently agreed CAT A equivalence for the NP and show that the F and the N, with their retro fit SB's, are equivalent to the NP. Rather than to start from square one with proving all the individual requirements.:ok:

In parallel, I am trying to find a copy of any relevant original document, which would be very helpful, as nobody seems to have one!! (They are all hidden in archives) Armed with a copy, I might be able to convince EASA to update the TCDS without further ado. We can all hope for miracles I suppose.:hmm:

Biz-Buz

biz-buz
26th Aug 2009, 09:13
As a more general request, there must be some rotorheads out there who operate, or whose company operates these aircraft to Class 1. Please could you ask your operations director what documentation they have to justify operating to Cat A equivalent; and more generally what is going to happen post 2010.

The AS355 is an old aircraft now but never the less a valuable one to operate either as a spare or on minor surveilance or EMS contracts, where the revenue does not justify a more modern aircraft.

biz-buz

biz-buz
26th Aug 2009, 09:21
Jim,

Further to your last, I think what I could expect is a document confirming Eurocopter's statement that the aircraft, with the correct retrofit parts, fitted, complies with the Engine isolation requirements, and if flown according to the corresponding part of the Flight Manual Supplement fulfills the Cat A equivalence requirements.

Obviously as the parts are not fitted on the assembly line, no definitive certificate can be issued (as per the NP), but as for certain versions of the BO 105, which is in the same boat, some sort of compromise can be reached I am sure.

Biz-Buz

Hullaballoo
27th Aug 2009, 13:05
The concept of "equivalent Cat-A" is interesting, since:

- it is an operational term (i.e., found in JAROPS-3 and not the certification rules). Does this imply that its use requires an Ops approval from a National Authority?

- it only provides for engine isolation (as JimL notes), but not guaranteed performance following loss of the critical engine.

- the term is not be found in the FAR's (27, 29, 91, or 135).

JimL
27th Aug 2009, 14:42
Hullaballoo,

'Equivalent Cat A' is not a definition per se but a language construct; it is provided because there are still, in operation, a number of Part 27 twins that were built before the introduction of Appendix C to Part 27 (AS355, Bo105, A109). JAR-OPS 3 acknowledges this fact and permits a route for acceptance of such twins if they meet the set of conditions that are provided in ACJ OPS 3.480(a)(1) and (2).

If you read and understand the text, you will see that it is an attempt at setting the minimum standard necessary to permit these aircraft to operate over a hostile environment. It is in fact the build standard that is provided in Category A certification (and is a minimum subset of the requirements of Part 27 Appendix C - which itself contains pointers to Part 29 rules).

Reading Paragraph 3 of the ACJ will also provide insight into the deficiencies in the provision of performance data in Part 29 - before revision 39. It indicates that (additional) scheduled performance data might be necessary to meet the requirements of Performance Classes 1 and 2 (Subparts G and H).

You will not find 'equivalent Cat A' in Parts 91 or 135 because those codes do not have performance standards for helicopters. Part 27 and 29 have no need for the description as they contain the certification codes for Category A.

As biz-buz has pointed out, the flexible part of the ACJ is in the assessment of engine isolation; this is written in those terms because MG3 of Part 27 contains guidance material for such an assessment.

As has been discovered by biz-buz, it is quite difficult to provide a definitive compliance document for each aircraft - hence the assessment sits in the lap of the Gods. The transition from JAR-OPS to EASA Ops has not made this any easier.

Jim

Mark Six
28th Aug 2009, 00:27
Don't know whether it helps but I have an old "EASA Approved" 355N Flight Manual Supplement which states "Though the helicopter is not certificated according to FAR 29 for Category A operation this supplement deals with the procedures and performance allowing the aircraft to be operated in a similar way". This particular supplement does not appear in later versions of the flight manual.

I also have a letter from DGAC which states "DGAC is pleased to confirm that the DGAC standard of AS355N is fit for the UKCAA Group A performance".

JimL
28th Aug 2009, 06:18
Mark Six,

You can see from the statement that this does not provide proof of compliance (in fact it confirms non-compliance); it deals with the provision of data for performance, not the additional elements (of ACJ OPS 3.480(a) and (b)) that are required for operations over a hostile environment.

Whilst that might suffice for some (non-JAA) States, it does not satisfy the basic requirement for certification in Category A (or assessment of equivalence).

Most of you will also know that whilst UK CAA Group A can provide a method of compliance with the objective set in ICAO Annex 6 Part III for PC1, the boundaries between the segments and the required climb performance are not the same as Category A. It might therefore be difficult (but not impossible) to establish compliance with the PC1 and 2 profiles that are described in Subparts G and H of JAR-OPS 3 as they were built around the parameters of Category A as provided in Parts 27/29.

Jim

Hullaballoo
29th Aug 2009, 21:47
Equivalent Cat A' is not a definition per se but a language construct

JimL,

Great points, and well articulated as always. I guess I've always taken the view that if a term is used in the regs, it's more than a "language construct"!

But I wonder if the the term truly only applies only to the older Part 27 twins? The 355NP is the perfect example -- it is the latest variant of the 355, and apparently meets some/most/not all, of Appendix C. (Then again, I suppose one could argue that it is "older aircraft," as I assume it carries the legacy cert basis :ugh: )

As to Paragraph 3: how does an operator come by the additional scheduled performance for PC 1 or 2? Is it left to each operator to develop and have approved? Or is he required to get data from the OEM? Confusing stuff!

In pointing out that the term isn't used in Parts 91 and 135, I was trying to highlight the fact that these parts don't even have performance requirements for FULL Cat-A, which is really too bad!

Thanks for you insight...

JimL
30th Aug 2009, 15:25
Hullaballoo,

As has been discovered, manufacturers are willing to provide scheduled data when it comes to selling new helicopters but have little interest for helicopters that are out of production. This is entirely logical because scheduling data requires a helicopter which has been instrumented for the task.

Manufacturers have provided continued development of sophisticated procedures such as: the extended TDP CAT A Procedures; back-up procedures with obstacles in the back-up path; and offshore procedures. Some of these procedures have resulted in scheduled data and others, in accordance with operational requirements, have been provided on the basis of modelled data (the offshore HAPS procedures, extensively used in the North Sea and elsewhere, are examples).

Some States have been willing to accept flight trial data from non-manufacturing organisations in support of operator defined procedures - the CAT A back-up procedure for the BO105 comes to mind (these are scheduled procedures).

One of the issues that has been problematical is the provision of data for PC2 and PC3; in ICAO Annex 6, PC2 and 3 take-off procedures are conducted AEO. This has never been a problem for helicopters certificated under BCARs (UK CAA) because there is a requirement for the provision of scheduled data to show the AEO distance to clear 50ft at a defined speed. This stemmed from ICAO Annex 8 Standard and is reproduced below:

Part IVA

2.2.3.1.4 Take-off distance required. (For performance Classes 2 and 3 helicopters only.) The take-off distance required shall be the horizontal distance required from the start of take-off to the point where the best rate of climb speed (Vy) or the best angle of climb speed (Vx) or a selected intermediate speed (provided this speed does not involve flight within the avoid areas of the height-velocity diagrams) and a selected height above the take-off surface are achieved, all engines operating at approved take-off power.
This is never an issue for Part 29 helicopters as it is covered by Part 29.63:

Sec. 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.
However, if you look at Appendix C of Part 27, this rule is not called up. The result is that, unless a helicopter has been certificated to BCARs, it is unlikely that the data will be in the Flight Manual.

In order to show obstacle clearance in the take-off phase of Performance Class 2, this data is required. Further, unless this distance is known, early entry into IFR cannot be established.

There is a further complication in that in Annex 14 - Heliports, there is necessity to provide this distance in order that the surface for a safe-forced-landing can be provided by the heliport designers. There is a table in ICAO Doc 9621 that gives estimated data but, without the appropriate graphs in the Flight Manual, compliance cannot be shown.

Most of these points are esoteric to most helicopter pilots but you did ask.

By the way, none of this has anything to do with the original subject which was about establishing compliance with the rest of the rules in ACJ OPS 3.480(a)(1) and (2).

Jim

biz-buz
31st Aug 2009, 09:40
JimL, Hullaballoo, Mark Six,

As you have proved, the whole issue is fraught with minor details, in essence the operational legislation provides for the method of operating the aircraft, and the certification legislation gives you the aircraft criteria which you need to fulfill in order to be able to operate to these minima. The F and the N already possess the Flight Manual Supplement, 11.2 for the F and Supplement 2 for the N, which give all required operational data to fly to PC1 through CAT A equivalence. The other various Eurocopter documents tell you what you have to do in order to comply with the Airframe requirements. On the performance side of things, it just means that you have to reduce your take-off weight in order to maintain the necessary OEI performance to be able to land safely or fly away, rather than have an organized crash!!:eek:

In order to accommodate existing aircraft, particularly in countries in EASA-land which may not have such a developed rotary infrastructure, ie which still operate a high proportion of the old twins, aka BO105, A 109, or AS355 F or N, the EASA operational team have fine tuned the Cat A certification requirements through the "Acceptable Means of Compliance" documentation which in effect through "grand-fathering" rights allow certain older types to operate, through CAT A equivalence.

The problem arises now because nobody is willing to step forward and give the EASA certification officer (Mark Winstanley) a copy of the DGAC approval letter which confirms that the AS355 has Cat A equivalence, ie does conform to legislation which was brought out after it was originally certified.

Thank you Mark Six for the kind offer of a copy of your DGAC letter, I would be very grateful if you could send me a good quality scan of this by mail; I will pm you now. If anybody else out there has any other relevant documents issued by the DGAC , however old, I would be grateful if you could let me know.:ok:

I will repost back here when this is sorted out, which will hopefully be soon!!

Biz-Buz