AW139 Cat. "A" and Cat. "B" discussion

[Bravo73]

Originally Posted by Copter Man

Yes Bravo thanks for clarifying it. So you can take off from a confined area at up to 6800 but not a wide open heliport with no obstructions around it. Yeah sure makes sense to me.

You need to read your RFM more carefully.

There is a difference between the vertical profile (6.4t) and the 'not quite vertical' (ie confined area - 6.8t) procedure. As Margins has pointed out, confined area/helipad is effectively just an Agusta definition. Not a physical restriction.

[tottigol]

CopterMan, if you don't mind, is it possible to know where did you receive your initial AW139 type training?
I am try to get some statistics going here, not trying to be indiscreet.

You can PM me if you want. Thanks.

[TunaSandwich]

I have a couple of questions about CAT A procedures for the AW139. For reference I am looking at RFM
Supplement 12 Cat A operations,
Supplement 50 6800kg and
Supplement 68 Phase 5 additional functions.

According to supplement 12
"For a Ground Level or Elevated Heliport/Helideck, without obstacles in the
take off flight path, the Vertical procedure with TDP fixed at 35ft can be used."

Nowhere does it say anything about a 20ft TDP option for the Elevated Helideck portion in supp 12. However in supplement 68 it talks about the CAT A takeoff symbology for ELEV HELIPAD which gives a 20ft TDP as default. It would be easy to assume that this option is for the Offshore Helideck Procedure, which uses a 20ft TDP, but the procedure for that in Supp 12 clearly states that a variable PI target should be used taken from the graph given. Therefore the symbology cannot be used as this gives a flat hover PI plus 23% at all hover PI's.

The caution below in supplement 68 comes with no reference and I was wondering if anyone knows more details for its meaning if there is no profile given for a 20ft TDP (except the offshore helideck)

Take-Off Symbology - Vertical Profile

The Take-Off profiles indicated on the PFD are to be used with the fol-lowing Supplement 12 CAT A Operation PARTs:

— HELIPAD - PART A - Ground Level and Elevated Heli-port/Helideck Vertical Take Off Procedure

— SHORT FIELD - PART B - Shortf Field Take Off Procedures

— ELEV HELIPAD - PART A - Ground Level and Elevated Heli port/Helideck Vertical Take Off Procedure

— BKUP HELIPAD - PART C Ground Level and Elevated Heliport/ Helideck Back-Up Procedure

When on the ground after selection of any vertical Take-Off profile the TDP height magenta bug is presented on the Rad Alt tape at the default value of 35 ft (85 ft for BKUP HELIPAD). This value should be modified, as required, for the profile being carried out using the DH rotary knob.

CAUTION

The ELEV HELIPAD displays a default TDP value of 20 ft which is lower than the PART A - Ground Level and Elevated Heliport/ Helideck Vertical Take Off Procedure TDP minimum so requires adjustment.


I'd like to know if anyone knows the correct use for the ELEV HELIPAD 20ft TDP symbology. It would be logical to me to say that it is intended for the Ground Level or Elevated Heliport/Helideck procedure when the elevation of the Heliport/Helideck is at least 15ft above the ground. But this is not mentioned in the RFM as far as I can see.

Thanks for your help.

[evil7]

Question Codeen

What I want to know exactly is:

What type of take-off/landing affords the HIGHEST level of safety during take off and landing of the AW 139 helicopter?

Answer

Definitely a rolling take-off / landing from / onto a runway

[Outwest]

Cat B procedures provide for minimum exposure to critical flight regimes during takeoff and landing. This also includes planning for a safe landing area in the mediate vicinity of the takeoff/landing spot should a loss of power be experienced. This procedure typically pertains to single engine machines but can be applicable to multi-engine aircraft that do not have the ability for continued flight after sustaining a loss of one engine. i.e. S-76A operating in Denver, CO

I guess that depends on the aircraft in question. The S61 RFM defines Cat B as the ability to attain a 10 ft wheel height. No mention what so ever about exposure during any phase of flight. I would hope we have come a bit further along since then but whenever I ask anyone at AW what is the definition of Cat B is they say " whatever is not Cat A"

[bpaggi]

Cat B Definition

The definitions of Cat B are fully defined in the airworthiness requirements which are CS/FAR 29 for large helicopters.
There are two types of Cat B envelopes (CS29/FAR29); one for helicopters with 9 or less passenger seats and one for more than 9 passenger seats.
Basic AW139 RFM provides the Cat B envelope for the more than 9 passenger seats configuration while Supplement 51 covers the 9 or less passenger seats configuration.
In the Basic RFM configuration the Cat B envelope provides assurance that for any take off/landing carried out outside of the H-V envelope within the maximum weight defined by the WAT charts a safe reject can be succesfully achieved after an engine failure provided this happens over a flat and prepared surface and up/from 50 ft height of the profile. Furthermore a climb capability at OEI CONTINOUOS rating is assured if the Vy is achieved. There is a undetermined portion of the take off profile from the climb out speed (50 KIAS) at 50 ft up to Vy where the regulation does not require a safe OEI capability (nonetheless the 139 is still capable in most of its envelope). The 139 in this Cat B enevlope guarantes also the in ground effect low speed controllability up to 40 kts from all directions.
The other Cat B envelope, that is included in Supplement B, there are no limitations (as per regulation requirements) other than the HIGE performance for take off and landings. Climb out or rejects are not required to be demonstarted although also in a considerable part of this envelope the 139 has such capabilities (providing a suitable surface is available for rejects).

[Geoffersincornwall]

Outwest et al

From a practical point of view there has to be something other than a Cat A procedure for take off and landing for it is simply not possible for all types of operations to comply with it's rigid protocols. This observation is especially poignant when the RFM emphasises that any deviation from the profiles defined in Supplement 12 etc. will render the performance data inapplicable. What constitutes a 'deviation'? Ten knots? five? twenty feet? ten? Very tricky to teach when you have that degree of inflexibility.

For those non Cat A operations (i.e.. the majority) they must do the best they can to manage the risks of operating from ad hoc sites (HEMS, POLICE, SAR, Corporate, VIP, VVIP, Private). Of course it would be handy if you could use the published Cat B profile but that was developed (or so I understand) in order to deliver the certification requirement (to state the distances required to land and take off over a fifty foot obstacle).

I suggest that it cannot be the case that no other take off or landing profile is permitted, if that were the case then we have a problem. The reality is that you do what you have to do and minimise the exposure to an engine failure. The AW139 has to be one of the best, if not THE best medium machine in that respect.

Teaching Cat B in the sim (and we are assured that the sim's performance mirrors the real aircraft) I can demonstrate that in the event of an engine failure during take off it's possible to bring ground speed back to zero or close to it at weights up to 6400 and thereby cope with poor terrain with minimum damage to the airframe.

The emphasis of Cat A is on climb performance whereas Cat B - or maybe I should call them 'non-Cat A' profiles - do not necessarily require a climb capability as long as you can see and avoid the obstacles.

So from my viewpoint it would be OK to say that a Cat B take off is anything that is not Cat A. In other words it is a profile that comes with no performance guarantees. Mr Baggi is an expert on the certification process and I bow to his knowledge and expertise in this respect but the operating world is much much bigger than that defined by the certification criteria. Maybe it will be necessary to have another way of describing profiles that are operationally essential but unable to fit those described by the certification process or we simply call the PC2 or PC3.

There are many out there who will use a familiar profile but are unable (or unwilling) to comply with the mass requirements or unable to quantify the obstacle environment with the accuracy required by the Cat A protocols. There are also those that do use a Cat A profile AND observe the mass limitations but due to operational constraints also have the problem of quantifying the obstacle environment. This is common when using ad hoc operating sites. None of these can be described as Cat A Operations and so they are unlikely to be PC1 compliant either.

G.

[Mars]

From 29.1 Applicability

(e) Rotorcraft with a maximum weight of
9072 kg (20 000 pounds) or less but with 10 or
more passenger seats may be type certificated as
Category B rotorcraft provided the Category A
requirements of CS 29.67(a)(2), 29.87, 29.1517,
and of Subparts C, D, E, and F are met.

Read the rules (understand the text) and follow the threads. You will find that the specified rules equate to the performance for Pure PC2 (with the condition of the surface defined only in operations regulations). This is because compliance with 29.1517 establishes a Limitation in the Flight Manual (which is required by regulations to be observed). Alleviation from 29.1517 may be provided by operational regulations under specified circumstances.

(f) Rotorcraft with a maximum weight of
9072 kg (20 000 pounds) or less and nine or
less passenger seats may be type certificated as
Category B rotorcraft.

These rules equate to Pure PC3 if the published Category B take-off and landing procedures are followed, and PC3 with exposure if they are not.

[pitpilot]

CAT A Class 2 Downwind Takeoff?

Here's one that has been doing the rounds recently. Anyone know if you can do a CAT A Class 2 downwind take off?
Looking in the RFM it says in all graphs that I can find tailwind is prohibited for CAT A. Therefore since Class 2 is grouped under CAT A along with PC1 etc.. It would seem that you cannot do this and you must use CAT B which has different profiles.
Looking at the post here I'm wondering if Class 2 refers only to Part of Class A certification I.e. The airframe regulations or to the performance side as well?
I know CHC used to do Class 2 departures downwind, however there seems to be a lot of confusion over the difference between class 2 and CAT B, with trainers sometimes assuming they are the same thing?

[HeliTester]

"Anyone know if you can do a CAT A Class 2 downwind take off?"

Are you asking can you do a Category A, Performance Class 2 takeoff? If so, I think they are mutually exclusive. (Perhaps Mars can help me out with that one). I think you can only do a Category A, Performance Class 1 takeoff. There are a lot of different terms here: CAT A, Class 2, PC1, Class A, Class A certification. Does Class 2 mean PC2? What does Class A mean, and what is a Class A Certification? Are we mixing apples and oranges? That is, are we mixing/interchanging certification regulations with operations regulations?

[[email protected]]

Cat A and B are what the aircraft are certified to do - PC1,2,2e etc are the profiles flown to meet the regulations and criteria pertaining to Cat A and B.

[Torquetalk]

CAT and performance classes
Here is a small attempt to sort these ideas out a bit for some of the posters (and perhaps readers) who are trying to sort them out: It isn’t meant to be definitive and is not aimed at those who have a good knowledge of this stuff.


CAT A – is about certification of complex helicopters with more than one engine. The key concept for pilots is stay up capability following an engine failure. Only got one engine? You can’t. So single engine helicopters are never certified CAT A. And neither are some twins; because they don’t meet other design criteria, or because they are pretty rubbish at staying aloft following an engine failure at their certified max weight.
CAT B – not CAT A (not meeting design criteria for certification or having no stay-up capability).
Performance classes – important if you operate where CAT A is broken down into full stay-up capability and stay-up capability once the helicopter has reached a certain speed. Perhaps the best example is offshore operations in Europe, such as the take-off from a platform:
Performance class 1 – stay-up capability (and the ability to climb) following an engine failure after the take-off decision point (no need to ditch), or a safe landing before (land back on the platform).
Performance class 2 – stay-up capability (and the ability to climb) following an engine failure once the aircraft has reached a certain airspeed, or a forced landing before (you’ll have to ditch).Until you reach that speed there is “exposure”.
So CAT A, Performance Class 1 is the gold standard (for this particular risk). A properly defined and flown procedure means the aircraft can suffer an engine failure at any stage of the flight and the outcome should be no risk to aircraft or occupants.

[JimL]

Hi Torquetalk,

It's very brave of you to set yourself up as a target.

(Most of that which is said below applies when more than nine passengers are carried.)

As Mars posted, the absolute performance requirement is set out in Part 29.1; however, caution is advised because, I am reliably informed, no helicopter has been submitted solely for certification in accordance with 29.1(e) - i.e. all the Category A requirements except for Subpart B - Flight (with the exception of those three stipulated). Manufacturers submit their helicopters for Category A certification when equipped with more than nine seats - i.e. they ignore the break at 9,072 kg.

When compliance is shown with 29.1(e) (specifically, in compliance with 29.25 and 29.67(a)(2)) the resulting performance graph represents the Category A WAT - which can be used for establishing the PC2 take-off mass.

The difference from certification in 29.1(c) and 29.1(e) is the requirement to provide the Category A 'procedures/profiles'; as Mars said, the three rules mentioned are those which equate to operations in PC2 - i.e. the provision of an HV diagram, its stipulation as a limitation and second segment performance.

The main reason this is being penned (apart from providing additional information), is because of the statement in your post:

"because they don't meet other design criteria, or because they are pretty rubbish at staying aloft following an engine failure at their certificated max weight"

That can only be true for Part 27 twins (which have not been submitted for Category A certification), or Part 29 twins that are not intended for passenger transport (I don't know of any).

The whole amendment of Part 29.1 in 'FAA NPRM 80-25' (and the introduction of a discriminant of more than 9 passengers) was to permit a lower certification basis for utility helicopters only (or utility operations for those submitted for dual certification).

Jim

[SFIM]

isn't the root of the confusion here that Agusta are using confusing terminology.

they talk about "CAT A and B profiles" when they mean PC1 and PC2.

PC1 and PC2 require "CAT A certification" which the 139 has.

the CAT A operations are in Supplement 12 in the RFM rather than the basic RFM because the helicopter was originally approved under "CAT B certification" then was upgraded to "CAT A certification" later.

I blame Agusta me, comments

Update :- clearly I am wrong based on Geoffers comments below, but in my experience almost everybody is confused about this one way or another.

[Geoffersincornwall]

SFIM

No confusion at the helicopter division of Finmeccannica - Cat A and Cat B are certification standards and the RFM is written as part of the certification requirements.

The PC1, PC2 and PC3 operating standards are mandated only in those areas that accept this ICAO definition. EASA being one of them. Elsewhere you will find an assortment of FAA and hybrid approaches to operating standards or none at all. A

As things stand at the moment there is the prospect of the two (Certification standards and operating standards) being found in the same official manufacturer's Flight Crew Operating Manual. Coming your way..... one day...

Watch this space.

G.

[JimL]

In certification, the provision of Category A and/or Category B procedures/profiles is required. The manufacturer provides these, meeting the specific conditions set out in the requirements (hopefully, utilising the guidance). They ensure that, following a power-unit failure, a safe landing (to the conditions required) can be achieved by an average pilot:

• The Category B procedure/profiles ensures that flight is conducted outside of the HV Diagram (the surface over which the take-off/landing is conducted is defined);
• Category A procedures/profiles are flight tested to ensure that they can be constrained within a safe flight envelope (i.e. the HV Diagram is not applicable).

The question of whether these procedures/profiles are mandated is moot; for Category A, it really depends on the contents and intent of the definition of 'Category A' applied in the State of Operation. In European regulations, they are not mandated.

In ICAO Standards and EASA regulations, only the objective criteria is specified, the procedure/profile to be flown is not. Provided the criteria can be met, any profile is available to the pilot. If there are constraints, they are to be found within the instructions issued by the organisation that has Operational Control.

Procedures contained in the non-approved section of the Flight Manual do not have to have Approval by the Certificating Authority; they are offered as best practice for acceptance by the Operational Oversight Authority.

For those with more than a passing interest in the Category A/Category B certification discussion (described above, for the AW139, by Dino Baggi), Appendix B of the following document contains a dissertation on "Appropriate Standards for Passenger Carriage".

https://www.dropbox.com/s/uh634o35dh...A-CHC.pdf?dl=0

https://onedrive.live.com/redir?resi...int=file%2cpdf

Other parts of the document describe elements that are germane, mostly, to the application of the HV diagram - although they do chart the history of the amendments to Part 29.1 (and associated rules) with respect to Passenger Carriage/Utility Operations (aerial work) and the nexus between certification and operations.

Jim

[bpaggi]

CAT A procedures for the AW139

TunaSandwich

I'd like to know if anyone knows the correct use for the ELEV HELIPAD 20ft TDP symbology. It would be logical to me to say that it is intended for the Ground Level or Elevated Heliport/Helideck procedure when the elevation of the Heliport/Helideck is at least 15ft above the ground. But this is not mentioned in the RFM as far as I can see.

The ELEV HELIPAD 20 ft TDP symbology needs adjustment to a minimum of 35 ft for the correct usage. This was initially develloped for the intended use on oil rig (Cat A Offshore) but never completed. This simbology must be used as per the HELIPAD simbology (duplication) either ground base or elevated.
It should not to be used for Cat A Offshore procedures, this profile is not included in the simbology.

[TunaSandwich]

Thanks a lot bpaggi for the explanation and confirming my suspicion. It does cause a lot of misunderstanding though as several operators are using that symbology for CAT A offshore helideck procedures.
TS

[TunaSandwich]

bpaggi

The ELEV HELIPAD 20 ft TDP symbology needs adjustment to a minimum of 35 ft for the correct usage. This was initially develloped for the intended use on oil rig (Cat A Offshore) but never completed. This simbology must be used as per the HELIPAD simbology (duplication) either ground base or elevated.
It should not to be used for Cat A Offshore procedures, this profile is not included in the simbology.

Is there any improvement or clarification with phases 7/8 that you know of?

TS

[bpaggi]

Is there any improvement or clarification with phases 7/8 that you know of?

At the moment there is no plan to update the symbology but the revision that will be certified in a few days will include an enhanced Cat A Offshore procedure that will slightly change the technique (harmonized with 189) and will provide greatly improved takeoff performance.
This technique is ground speed based without reference to attitude changes maintaining the AEO procedures.
All the other procedures are unaffected.