AW189
Can you please share with us what CatA/PC1 profiles are available for the AW139?
PT5.
Ok. So we have a very modern helicopter that can't carry out a Cat A/Class 1 Clear Area departure from the hover?
And you don't think that this is an 'issue'? Eurocopter/Airbus Helicopters must be laughing their heads off.
And you don't think that this is an 'issue'? Eurocopter/Airbus Helicopters must be laughing their heads off.
Join Date: Nov 2005
Location: Worldwide
Posts: 26
Likes: 0
Received 0 Likes
on
0 Posts
tottigol has it right regarding sale rates I reckon. 
There have been plenty of people available to cut down the AW139...meanwhile AW quietly continued to saturate the market with their product.
Lets not forget that when the AW139 first come out it had a payload of 6400kg's and many a comment was made about much the same things as we see on the AW189 thread right now
Some here are a bit sensitive on the subject...but in the end the ball will keep bouncing. I reckon we just need to take a breath and see what happens during the first year or so of operation by the industry to know where AW are at with their new toy.
SS
There have been plenty of people available to cut down the AW139...meanwhile AW quietly continued to saturate the market with their product.
Lets not forget that when the AW139 first come out it had a payload of 6400kg's and many a comment was made about much the same things as we see on the AW189 thread right now
Some here are a bit sensitive on the subject...but in the end the ball will keep bouncing. I reckon we just need to take a breath and see what happens during the first year or so of operation by the industry to know where AW are at with their new toy.
SS
Join Date: Nov 2005
Location: Worldwide
Posts: 26
Likes: 0
Received 0 Likes
on
0 Posts
TS-ouch 
chill Winston
You have surmised that the AW189 can only carry 8 pax a short range...and then deduce that it's not impressive without knowing why this flight and payload took place...well your POV is as valid as anyone's here I guess.
In the meantime the ball keeps bouncing
SS
chill Winston
You have surmised that the AW189 can only carry 8 pax a short range...and then deduce that it's not impressive without knowing why this flight and payload took place...well your POV is as valid as anyone's here I guess.
In the meantime the ball keeps bouncing
SS
‘Bravo73’, the situation with respect to the AW189 performance is far more complex than you or ‘tottigol’ have portrayed.
Leaving aside the ‘clear area’ procedure for a moment and looking at the Category A vertical procedure using ‘ISA’ as a reference point (+15C and 0 PA), it has an RTOM of 8050kg (MCTOM 8300 kg):
(In the performance section of the RFM, a similar WAT curve (for vertical reject and fly-away) is provided for all categories – in fact it appears to be a mirror image of the reject curve. This replaces the H-V Diagram, quite legitimately, using the converse of the wording from 29.1517 “if a range of heights exist at any speed, including zero, within which it is not possible to make a safe landing following power unit failure…”)
In the performance section, there are WAT and take-off procedures for Category B: one from a HIGE and a second with a rolling start; there is a ‘Category B take-off distance chart’ that applies equally to both. It is not clear if there is any advantage for one over the other because, for both techniques, the RTOM are identical. The MCTOM of 8300 kg applies for quite a wide operating envelope.
There is presently only one Category A ‘clear area’ procedure – rolling to 25kts (how does the pilot know when that has been achieved unless it is GPS derived and displayed on the PFD?); at 25kts GS the reference Tq (PI target – the Tq to achieve a 2m hover) is pulled and the helicopter is climbed to the TDP of 30ft. it is not intuitively obvious what advantage is gained by using this rolling technique bearing in mind that the mass for this procedure is not much greater than that for the vertical (at ISA, 8300 kg as opposed to 8050 kg).
One disadvantage with this procedure is that it cannot be used in PC2 under circumstances where the surface would permit a safe-forced-landing but not a running take-off or reject.
There is no Category A take-off mass WAT as specified in 29.25(a), 29.67(a)(2) and required by 29.1519 but this is not unusual for European helicopters certificated by EASA (we know not why)! AH do provide this in the performance data for the AH225 but not in the limitations section (the S92 has it in the limitations – i.e. in compliance). This data is required for operations in PC2 in order to determine the second segment climb and therefore the take-off mass.
Comparison with other helicopters is difficult because of the unique way that data has been provided.
I stand to be corrected on any/all of this.
Jim
Leaving aside the ‘clear area’ procedure for a moment and looking at the Category A vertical procedure using ‘ISA’ as a reference point (+15C and 0 PA), it has an RTOM of 8050kg (MCTOM 8300 kg):
- the procedure is to climb vertically to 110’ (TDP};
- following an engine failure at, or before, 110ft it can reject vertically to the helipad;
- following an engine failure at or after TDP, it can perform a Continued Take-off (CTO) clearing the surface by 15ft.
(In the performance section of the RFM, a similar WAT curve (for vertical reject and fly-away) is provided for all categories – in fact it appears to be a mirror image of the reject curve. This replaces the H-V Diagram, quite legitimately, using the converse of the wording from 29.1517 “if a range of heights exist at any speed, including zero, within which it is not possible to make a safe landing following power unit failure…”)
In the performance section, there are WAT and take-off procedures for Category B: one from a HIGE and a second with a rolling start; there is a ‘Category B take-off distance chart’ that applies equally to both. It is not clear if there is any advantage for one over the other because, for both techniques, the RTOM are identical. The MCTOM of 8300 kg applies for quite a wide operating envelope.
There is presently only one Category A ‘clear area’ procedure – rolling to 25kts (how does the pilot know when that has been achieved unless it is GPS derived and displayed on the PFD?); at 25kts GS the reference Tq (PI target – the Tq to achieve a 2m hover) is pulled and the helicopter is climbed to the TDP of 30ft. it is not intuitively obvious what advantage is gained by using this rolling technique bearing in mind that the mass for this procedure is not much greater than that for the vertical (at ISA, 8300 kg as opposed to 8050 kg).
One disadvantage with this procedure is that it cannot be used in PC2 under circumstances where the surface would permit a safe-forced-landing but not a running take-off or reject.
There is no Category A take-off mass WAT as specified in 29.25(a), 29.67(a)(2) and required by 29.1519 but this is not unusual for European helicopters certificated by EASA (we know not why)! AH do provide this in the performance data for the AH225 but not in the limitations section (the S92 has it in the limitations – i.e. in compliance). This data is required for operations in PC2 in order to determine the second segment climb and therefore the take-off mass.
Comparison with other helicopters is difficult because of the unique way that data has been provided.
I stand to be corrected on any/all of this.
Jim
Join Date: Oct 2002
Location: 1 Dunghill Mansions, Putney
Posts: 1,797
Likes: 0
Received 1 Like
on
1 Post
Originally Posted by Swinging Spanner
when the AW139 first come out it had a payload of 6400kg
Mods - Further to Swinging Spanner's point about tracking the performance and perception of the AW189 over time, could you merge all of the various threads into the original to maintain a single comprehensive thread, in common with what we have for the S-76D and EC175?
I/C
Some additional info following Jim's points: http://easa.europa.eu/system/files/d...1587(b)(6).pdf
The S92 graphs go to 300 ft, and it's a vertical procedure - though one could argue that the geometry is such that to maintain the sight picture there is a default movement back and left.
I have my doubts, however, that there are sufficient visual reference to reject vertically from this height to an elevated helipad, let alone higher).
Originally, there was no DfT spec for the number of aircraft but there was an availability requirement.
The rescue capabilities and RoA were as follows.
Lot 1: "... minimum rescue capacity per aircraft of 8 casualties/survivors (2 of which are stretchered) and a minimum radius of action of 200nm (250nm at Stornoway)".
Lot 2: "... minimum rescue capacity per aircraft of 4 casualties/survivors (2 of which are stretchered) and a minimum radius of action of 170nm"
Amongst the bidders it is understood that there were proposals for 7 aircraft per lot, probably consisting of one servicing spare and one accident spare.
Then the DfT got cold feet (around the time of the 2 Super Puma ditchings). The spec then became 2 aircraft per base with the theory being that if one type was grounded then the other type could provide coverage.
Bristow now state the S-92 RoA as 250nm and the AW189 as 200nm. The interactive coverage map on the Bristow SAR website shows the coverage.
SAR Coverage Map | Bristow Search and Rescue
At least 70% of UK SAR helicopter jobs are land jobs. Full tanks are unhelpful for Land SAR search jobs since aircraft turn up unable to deploy enough searchers. First indications are that the AW189 may be less prone to this drawback than either SK or S-92 but the proof of the pudding is in the eating.
Some musing on AW189 performance.
Leaving aside the issue of the requirement for the H-V diagram when Category A is not mandated, let’s see what the performance data tells us.
For Category A: we can see that the ‘clear area’ procedure permits maximum mass operations up to 4000ft and 20⁰C. The ‘vertical’ procedure at MSL and 15⁰C permits a RTOM of 8,050 kg with nil wind increasing to 8,200 kg with 20 kts (all accountable headwinds are already factored at 50% in the graphs). Like most others I am baffled by the ‘rolling take-off’ clear area procedure (as stated earlier); some explanation would be extremely helpful.
There is a strong correlation between the Category A ‘vertical’ procedure and the Category B graphs for ‘reject’ and ‘fly-away’ (if one take the Category A ‘vertical’ procedure with its TDP at 110ft and reconstructs it with the Category B ‘reject’ and ‘fly-away’ graphs with the same drop down, one mirrors the other). The reject graph however, has a maximum height of 200ft!
With respect to Performance Class 2; the flight manual states that the second segment climb performance (150ft/min required) is assured if the Category B ‘fly-away’ graph is used. However, that doesn’t tell us enough (because that may not be the profile that is used). What can be seen from the performance graphs however is with the offshore regime (the ISA conditions of +15C and MSL) at Vy with MCTOM of 8300 kg:
We already know that the ‘reject’ graph provides us with sufficient data (reliably) to predict what will result from an engine-failure before the ‘Rotation Point’ (RP - which we can choose) or after ‘Committal Point’ (CP - which we can also choose). The ‘fly-away’ graph permits us to tailor our take-off mass to the drop-down – both for take-off and landing. The ‘fly-away’ graph has wind accountability (without factoring) - although the first 20 kts of wind is ‘shaded’ because it is said that the airspeed system is unreliable up to that speed (without knowing whether that might be a factor in performing the fly-away’ profile, it is difficult to assess whether it is or is not an issue; realistically, we have a reasonable accurate wind vector from the rig which we could factor and apply). Working backwards from the drop-down height, we can establish safe* Performance Class 2 take-off or landing masses.
* With the proviso that we cannot assure deck-edge clearance – so what’s new?
Now to calculate some figures: using the established average deck height in the North Sea of 98ft, and the height of the RP and CP as our sea-miss distances (once again using ISA conditions) – the PC2 take-off mass and landing masses (without ditching exposure) will be:
Leaving aside the issue of the requirement for the H-V diagram when Category A is not mandated, let’s see what the performance data tells us.
For Category A: we can see that the ‘clear area’ procedure permits maximum mass operations up to 4000ft and 20⁰C. The ‘vertical’ procedure at MSL and 15⁰C permits a RTOM of 8,050 kg with nil wind increasing to 8,200 kg with 20 kts (all accountable headwinds are already factored at 50% in the graphs). Like most others I am baffled by the ‘rolling take-off’ clear area procedure (as stated earlier); some explanation would be extremely helpful.
There is a strong correlation between the Category A ‘vertical’ procedure and the Category B graphs for ‘reject’ and ‘fly-away’ (if one take the Category A ‘vertical’ procedure with its TDP at 110ft and reconstructs it with the Category B ‘reject’ and ‘fly-away’ graphs with the same drop down, one mirrors the other). The reject graph however, has a maximum height of 200ft!
With respect to Performance Class 2; the flight manual states that the second segment climb performance (150ft/min required) is assured if the Category B ‘fly-away’ graph is used. However, that doesn’t tell us enough (because that may not be the profile that is used). What can be seen from the performance graphs however is with the offshore regime (the ISA conditions of +15C and MSL) at Vy with MCTOM of 8300 kg:
- At OEI 2 minute power, the ROC is in excess of 700ft/min (to above 50⁰C);
- At OEI MCP, the ROC is in excess of 350ft/min (to above 35⁰C);
We already know that the ‘reject’ graph provides us with sufficient data (reliably) to predict what will result from an engine-failure before the ‘Rotation Point’ (RP - which we can choose) or after ‘Committal Point’ (CP - which we can also choose). The ‘fly-away’ graph permits us to tailor our take-off mass to the drop-down – both for take-off and landing. The ‘fly-away’ graph has wind accountability (without factoring) - although the first 20 kts of wind is ‘shaded’ because it is said that the airspeed system is unreliable up to that speed (without knowing whether that might be a factor in performing the fly-away’ profile, it is difficult to assess whether it is or is not an issue; realistically, we have a reasonable accurate wind vector from the rig which we could factor and apply). Working backwards from the drop-down height, we can establish safe* Performance Class 2 take-off or landing masses.
* With the proviso that we cannot assure deck-edge clearance – so what’s new?
Now to calculate some figures: using the established average deck height in the North Sea of 98ft, and the height of the RP and CP as our sea-miss distances (once again using ISA conditions) – the PC2 take-off mass and landing masses (without ditching exposure) will be:
- Zero wind = 7,800 kg;
- 20 kts wind (factored) = 8,200 kg
Join Date: Jul 2013
Location: UK
Posts: 193
Likes: 0
Received 0 Likes
on
0 Posts
With lot 1 and 2 base transitions commencing on 1st April 2015, we should see initial platform deliveries to cover pre-transition training on their way pretty soon and then we will know fact from fiction.
Scottish Mountain Rescue
Casbag Edn 34
"This is a new aircraft type and certification of the oil and gas variant by the European Aviation Safety Agency was issued on the 7th May 2014. The first example of the SAR variant is [late May 2014] being built in Milan and is expected to be completed shortly. This will be a major watershed in the project, allowing significant progress with test and certification, aircrew training and operating procedures. The second example will be built at Yeovil and is expected to be ready by late October 2014.
The top specification of flight simulator, configured for the AW189, was certified at Milan in March 2014 and this supplements a flight training device (without motion systems) that was certified in September 2013. A flight simulator configured as a SAR AW189 is due to be installed at Bristow in Dyce in mid-2015. AW189 maintenance dominates the Agusta Westland Training Academy engineering course calendar for the remainder of 2014.
... ...
The target for EASA certification of the SAR variant is believed to be October 2014. Even then, the Full Icing Protection System (FIPS) will not be certified and aircraft will enter SAR service in April 2015 with the standard icing protection system [LIPS] only. This is an improvement on Sea King capability so it is not a huge impediment to operations. FIPS test and certification requires winter conditions and there is no replacement for a full season of challenging conditions. The final outcome is expected to be an aircraft ready to take full advantage of all that dense winter air.
November might be a more realistic target for certification of the SAR variant but if it creeps out beyond the end of the year then things start to get difficult. The DfT have stated that they are satisfied with Bristow’s back-up plan should the AW189 not be ready to enter service in April 2015. However, neither the DfT nor Bristow have stated what that plan is. Two versions exist in the helicopter industry rumour network. Version One involves using S-92 airframes but where those airframes are to come from is not clear. New S-92 for Sumburgh and Stornoway, before 2017, are also rumoured and if such a plan is in place then its delay might provide the necessary airframes. The S-92 version allows full Contract Lot 2 capability. This version alters the training load because of the need for S-92 aircrew who will later fly in AW189. Version Two involves using Agusta Westland AW139 SAR airframes. Two such aircraft are said to be currently in build. This is similar to the aircraft currently operated by CHC at Lee-on-Solent and Portland. This version of events is not compliant with the contract because of the aircraft’s smaller cabin and reduced radius of action so it would be expected to attract contract fines. EASA reports indicate the likelihood of a reduced type-rating course, allowing credit for prior experience on AW139, so the training load is expected to be reduced. The number of mountain rescuers carried would probably be no more than in a fully fuelled Sea King on a hot summer afternoon, except all the time. Hopefully, we will never need to know which version is correct."
Sources:
DfT/MCA/Bristow/AW/Pilot1/Pilot2/A N Other1/A N Other2
Casbag Edn 34
"This is a new aircraft type and certification of the oil and gas variant by the European Aviation Safety Agency was issued on the 7th May 2014. The first example of the SAR variant is [late May 2014] being built in Milan and is expected to be completed shortly. This will be a major watershed in the project, allowing significant progress with test and certification, aircrew training and operating procedures. The second example will be built at Yeovil and is expected to be ready by late October 2014.
The top specification of flight simulator, configured for the AW189, was certified at Milan in March 2014 and this supplements a flight training device (without motion systems) that was certified in September 2013. A flight simulator configured as a SAR AW189 is due to be installed at Bristow in Dyce in mid-2015. AW189 maintenance dominates the Agusta Westland Training Academy engineering course calendar for the remainder of 2014.
... ...
The target for EASA certification of the SAR variant is believed to be October 2014. Even then, the Full Icing Protection System (FIPS) will not be certified and aircraft will enter SAR service in April 2015 with the standard icing protection system [LIPS] only. This is an improvement on Sea King capability so it is not a huge impediment to operations. FIPS test and certification requires winter conditions and there is no replacement for a full season of challenging conditions. The final outcome is expected to be an aircraft ready to take full advantage of all that dense winter air.
November might be a more realistic target for certification of the SAR variant but if it creeps out beyond the end of the year then things start to get difficult. The DfT have stated that they are satisfied with Bristow’s back-up plan should the AW189 not be ready to enter service in April 2015. However, neither the DfT nor Bristow have stated what that plan is. Two versions exist in the helicopter industry rumour network. Version One involves using S-92 airframes but where those airframes are to come from is not clear. New S-92 for Sumburgh and Stornoway, before 2017, are also rumoured and if such a plan is in place then its delay might provide the necessary airframes. The S-92 version allows full Contract Lot 2 capability. This version alters the training load because of the need for S-92 aircrew who will later fly in AW189. Version Two involves using Agusta Westland AW139 SAR airframes. Two such aircraft are said to be currently in build. This is similar to the aircraft currently operated by CHC at Lee-on-Solent and Portland. This version of events is not compliant with the contract because of the aircraft’s smaller cabin and reduced radius of action so it would be expected to attract contract fines. EASA reports indicate the likelihood of a reduced type-rating course, allowing credit for prior experience on AW139, so the training load is expected to be reduced. The number of mountain rescuers carried would probably be no more than in a fully fuelled Sea King on a hot summer afternoon, except all the time. Hopefully, we will never need to know which version is correct."
Sources:
DfT/MCA/Bristow/AW/Pilot1/Pilot2/A N Other1/A N Other2
Further musings on performance
In a previous post, reference was made to the ‘clear area’ procedure and the rolling take-off to 25 kts GS. On further examination, it is seen that this is not the only reference to ground speed in the Category A performance section; it is also used in: failure before TDP (rejected take-off); approach to LDP (balked landing); LDPs; and to refine the balked landing manoeuvres – in fact anywhere a reference speed is 40 kts or below.
For the flight testing regime, the ‘allowable wind’ is for the flight test team to decide but, for vertical take-off and landing, general guidance is that it should be at ‘0 to 3 knots’ (AC 29.45(b)). It is likely therefore that an instrumented helicopter has accurately demonstrated all the points/manoeuvres referred above. I can imagine that there was a discussion in certification with respect to speeds below 40 kts, where the (raw data) ASI is known to be inaccurate, leading to this inappropriate use of GS to be applied.
Most of the referenced points/manoeuvres are airspeed sensitive (not ground speed) and reference to GS is therefore non-sequitur. This unique way of describing reference points/manoeuvres either has to be conditioned by explanation along with examples of practical use or a reversion to airspeed applied. It strikes me that providing an RFM to suit the certification process and not the pilot is not such a good idea.
Flight operations in the higher latitudes rarely encounter calm conditions (luckily) – in fact the mean wind offshore is 20 kts. It is unlikely that the pilot will reference the ground speed during his scan of the instruments (it usually sits on its own in an undefined location somewhere in the PFD/MFD), and only the most sophisticated autopilots can fly to the lowest speeds referred to in the RFM. In fact only with respect to siting over/near the landing spot will GS be an issue.
For these reason, reference to ground speed in the RFM is of little use unless the wind conditions are calm – which they rarely are – and/or ground speed becomes a primary reference parameter (as it has become from some offshore approach procedures).
Jim
In a previous post, reference was made to the ‘clear area’ procedure and the rolling take-off to 25 kts GS. On further examination, it is seen that this is not the only reference to ground speed in the Category A performance section; it is also used in: failure before TDP (rejected take-off); approach to LDP (balked landing); LDPs; and to refine the balked landing manoeuvres – in fact anywhere a reference speed is 40 kts or below.
For the flight testing regime, the ‘allowable wind’ is for the flight test team to decide but, for vertical take-off and landing, general guidance is that it should be at ‘0 to 3 knots’ (AC 29.45(b)). It is likely therefore that an instrumented helicopter has accurately demonstrated all the points/manoeuvres referred above. I can imagine that there was a discussion in certification with respect to speeds below 40 kts, where the (raw data) ASI is known to be inaccurate, leading to this inappropriate use of GS to be applied.
Most of the referenced points/manoeuvres are airspeed sensitive (not ground speed) and reference to GS is therefore non-sequitur. This unique way of describing reference points/manoeuvres either has to be conditioned by explanation along with examples of practical use or a reversion to airspeed applied. It strikes me that providing an RFM to suit the certification process and not the pilot is not such a good idea.
Flight operations in the higher latitudes rarely encounter calm conditions (luckily) – in fact the mean wind offshore is 20 kts. It is unlikely that the pilot will reference the ground speed during his scan of the instruments (it usually sits on its own in an undefined location somewhere in the PFD/MFD), and only the most sophisticated autopilots can fly to the lowest speeds referred to in the RFM. In fact only with respect to siting over/near the landing spot will GS be an issue.
For these reason, reference to ground speed in the RFM is of little use unless the wind conditions are calm – which they rarely are – and/or ground speed becomes a primary reference parameter (as it has become from some offshore approach procedures).
Jim
Join Date: Feb 2003
Location: Somerset
Posts: 282
Likes: 0
Received 0 Likes
on
0 Posts
maybe a dumb question....
but if the ASI isn't reliable at low speeds, what other speed are you going to use apart from ground speed?
I guess the Flight Test Team knew what they were doing and the Cert authorities are happy with the RFM produced, so why question what it says?
DM
I guess the Flight Test Team knew what they were doing and the Cert authorities are happy with the RFM produced, so why question what it says?
DM