AS350 Astar/Squirrel

[victor papa]

When do you check your oil level and replenish? It is critical to chk the level as soon as possible after shutdown and no longer than 15 min after shutdown as stated in the FLM. The oil drains back into the MO1 so the level you see is not representative of the oil in the system but only in the reservoir. If after shutdown the level is on min or just above it is correct and do not add oil afterwards even if you can see no oil level in the side glass-if uncertain do a ground run to oil t 65 degrees and shutdown and check or open the spout and normally if level is ok you will see the oil.


She is dumping the excess oil out the breather to prevent over pressurising the system. Continuous over filling will lead to the mag seal in the MO1 and MO5 starting to leak.


Hope this helps

[Bush350]

Thanks for the reply. We know those things and run the oil level as low as possible to reduce the amount available to vent, but this doesn't seem like it is making any kind of difference. Adding oil as req'd is a no brainer but I am trying to figure out a way to stop the constant venting. Operating in the colder temps of N Canada makes for one very ugly a/c but in reality, there is no logical reason for the design to be just pulling oil out of the reservoir. I am hoping to find someone who has adjusted the vent pipe or changed the rigging on the line or something to significantly reduce the 1L/20 hrs of oil getting blown out the back end.

[victor papa]

Ok, clearly the biggest culprit is eliminated then. Next thing is to check rooting of pipe from reservoir where it makes the circle before the firewall. The circle in the pipe has to be a certain diameter as per the AMM. Biggest problem is tie wraps. Often the pipe gets tie wrapped tightly to the MGB stay on 2 places. This causes a kink or narrowing or square shape whatever you want to call it in the pipe. If tie wrapped then try without and ensure circle correct and pipe diameter constant in shape and diameter. Its very sensitive esp in cold weather due higher initial pressure. If you look at the T junction on the vent line just behind the starter whos drive is the breather, is their signs of oil mist or sogginess on the rubber pipe joining the T piece?

[Bush350]

When we first got the machine, one of the first things we did was change the loop on the vent line as it was too small. As far as the rest of your comments go, I am not on shift right now but will pass on your thoughts to the guys working on it now.

Thanks and will let you know how it works out.

[chiefedge]

One other thing to check is for coking in the vent tube its self, near the exit to the exhaust.
Look down the tube from the exhaust, you maybe surprised at the amount of carbon build up that is restricting the airflow.
We are having similar issues with the EC130.

[ROCK DOCTOR 123]

Funny how most B3 will vent excessively, We took it upon ourselves to reverse the vent tube angle as a trial a few years ago and fixed the venting problem on our 5 B3s They are brerathing much better these days. Turbomeca is aware of the inharent venting and of our modification but did not discourage our practice..

[Bush350]

We cleaned the coking out of the tube pretty early but of course the problem persists. But reversing the angle of the tube is a new one. So you turned it down so that it faces the ground? It would actually make sense as I think the exhaust probably creates a vacuum and that is probably the greatest issue to overcome. Do you have a pic?

Thanks

[Nubian]

Is your goal to reduce the oil-consumption to zero? Good luck
1L/20hrs is really not a bad stat. 1L/5hrs is the limit and from Turbomeca's side acceptable, specially if it is working hard.
We had a B3 suddenly using 0,5L an hour, and that turned out to be a partly clogged oil return line.

I don't think Rock Docktor turned the went line upside down, but changing the angle of the top of the went line i.e cutting it slightly. I have heard this been done, but for me the most important thing is to never overfill the reservoir. I always add oil just after shutdown as Victor Papa mentioned, and never more than half way between the bottom of the glas and the MIN line when parked flat.

[ROCK DOCTOR 123]

Your correct the vent tub is in its original location but just has the tube cut angle ground the opposite angle at 30 degrees open against the exhaust flow.

[Bush350]

That makes more sense. I will pass it on and see if it makes any difference. I can see reducing consumption to zero as nearly impossible but for an engine to be just sucking out oil and spraying it on the tailboom makes no sense at all.

[victor papa]

I didn't wanted to be so blunt as to suggest to run the oil level below min due some attitudes here. However, I played with oil levels on our machines and marked a new minimum where they breath least but maintain the level-some 100hr to 100hr. I had various discussions with the factory and 350 team at Marignane and they admit its a known problem but due certification can not change the level indicator. On the 365 its even worse as shes got the same tank with the same marking yet the engines are below the reservoir level so you need to chk quickly otherwise halve the reservoirs oil is in the MO1.


The key to the ARRIEL oil system is the breathing system. On machines that work hard and hovers a lot at MAUW I check the breather tube of the MO3 rear bearing regularly and clean it out-one just have to respect the AMM procedures whilst doing it carefully to avoid disaster. Oil mist or wetness on the rubber external tube running from the breather is a sign of breathing issues whether it is too much oil or a dirty or partially blocked breather tube internally or externally. The return line tube on the MO3 rear bearing can also cause major issues if partially blocked as the only place to get rid of the oil is threw the breather tube then. First sign of trouble will be coking of the MO3 rear bearing breathing tube and of course the flow check on the 600hr.


For machines that spend their life hovering a black tailboom is a given. Not all the oil from the MO4 bearing is scavenged and a very small amount gets dumped. In forward flight it spares the boom but in hover not.

[Bush350]

Yeah, I get it VP but as a long time Astar pilot, I know there have been a few different Oil Reservoirs over the life of the Astar so I find it strange that the res can't be modified. Heck, the original Lycoming used an opaque reservoir that would be perfect for this issue. That being said, I don't know enough about certifications to have a fair comment. And based on previous comments, you wouldn't know that I am probably the greatest Astar salesman in the world but since I spend a lot of time on the end of a longline, I find it a little disconcerting not really being able to tell what my oil level is or if there has been a sudden change in oil burn/consumption. Kinda sad that the operators have to be fixing the manufacturer's problems.

[Bell_Flyer]

Earlier in this thread there was discussions on counting cycles on the Turbomecca engined Astar. Can someone explain how cycles are counted and if they are different to the Ng Reference Cycle and Operating Cycles for the TM engines? Is there a Honeywell article that explains how to count cycles on the interwebs? Thanks.

[mlagersson]

I know its an old post, but Im sure someone will come across this again.
I found this interesting article; 2000-11-01 RON BOWER SOLOY ALLSTAR (http://www.bowerhelicopter.com/2000-11-soloy%20allstar.htm)
Interesting, but I also saw that Alexair is selling their, so who knows. I like the idea that there is a lot of people out that knows how to work on the 250 series, especially c20. And the c30 isnt that far off..

[The Tox]

Yeh, Jayrow had a few of them, got rid of them or converted them to Ds. The last one they had was in KTA and was the best money making machine ever, temp limited all the time and wouldn't pull the skin off a rice custard. Depending on the day, it was able to cruise some where around 95kts (maybe) and customers were paying by the hour. God bless 'em... lost a lot of money after that conversion with the LTS 650, it went a lot faster... Darn it!!

[Gemini Twin]

Your best bet today if you don't want to stay with the Turbomeca is Soloy's SD1 conversion kit using a Silver 600A-3A. Find out what the 1B will cost to overhaul and compare with the Soloy total kit price of $401,000.00.
It makes even more sense if you were to upgrade the helicopter to BA configuration at the same time. This engine in a BA runs rings round the standard ship at any temp. and altitude.

[fadecdegraded]

The reason the N1 (and TQ) are low when doing this is the blades are in autorotation and being driven. The FCU senses this and drops the engine rpm back to a lower amount. TQ will also be on zero ( or a very low amount) because there is no TQ the rotor system is in autorotation.

The guy in the video obviously did not know his machine, and by all accounts is a instructor and flight examiner. It was either a big show or he had no idea at all what was going on, i think the later.
Theres no way i would want to do a check ride with him with his lack of knowledge let alone do a rating with him, imagine the lack of knowledge the student would come away with, it would be dangerous.

[fadecdegraded]

Can only assume you meant TQ not NG.

The reason is the blades are being driven by the autorotation not by the engine.
If you simulate a auto with the rrpm a little bit high you will see the TQ on zero pull a bit of pitch and you will see the TQ rise as the engine starts to contribute the the power demands of the rotor system

[Nubian]

....that seems to be normal then I suppose...

Yes, that is normal.

The Delta NG gauge on the B2, is a ''somewhat early model'' of the FLI on the B3.(Only for NG of course) as it will depict your Altitude-Temperature corrected Max T/O power setting when the needle is pointing to 0 when NG is your limit.

So, the ''dropping to zero'' you're referring to is in reality below the -10 mark on the gauge and not 0 which is right at the top.

[jymil]

Your statement "the NG gauges needle dropping to zero when the NG is on 83" sounds like there is some confusion about what is shown in the gauge.
The pointer shows deltaNg whereas the digital display shows the absolute Ng value in percent.

The AFM states: 98%Ng = -3.5 deltaNg. The minimum deltaNg value shown by the needle is -10 or so. This means any Ng value under 91.5% goes together with the needle at the minimum position. The zero deltaNg position is actually in the middle of the gauge (max takeoff rating, i.e. the end of the yellow arc).

As for the video: the only reason why the intermittent sound goes on is high RPM. Corrective action would be to pull collective and cross-check with the NR gauge. If NR is green and agrees with Nf (in non-autorotative flight of course), then you can conclude the RPM gauge is telling you the truth and the horn is not.

[Shawn Coyle]

Edboldie:
I'd have the servos checked. There should be no stickiness, and you should never be on the stops of the controls (as long as you're within CG limits).

[Fun Police]

maybe try cleaning the cyclic friction cups first. it would be the simplest thing to start with.

if you are not two huge guys with very little fuel on board, i don't think that you should be anywhere near the rear stop on the cyclic in the hover. 350's are quite forgiving W&B - wise.

rigging perhaps?

fp

[Fun Police]

not that it would make THAT much of a difference; but do you have the battery in the tailboom?

fp

[Fun Police]

well then, i don't know why your cyclic would be on the aft "stop" in the hover unless there are C of G issues (assuming cabin loading has been accounted for).
have you calculated the weight and balance?
have there been any significant configuration changes recently?
please post what your engineer finds, i'd be interested to know what mechanical reasons there might be for this.
fp

[belly tank]

Ive flown the B2 for 8 yrs in utility work, namely fires and power line survey and never heard of these symptoms.

As Shawn has said check your servos and rigging. Id also check your accumulator pressure is at required values whilst your at it.

Another point, is your hyd pump supplying required pressure?.

Check your frictions are not binding also, i like to fly with a little friction on both controls but i always check they are full and free on control checks prior to applying a little friction.

I like others are interested in your outcome.:ok:

[helimo]

I am looking for an EASA certified EMS Kit for the 350/355 series. Used condition and preferably from Europe would be the best. Any ideas ?

[Ready2Fly]

I am currently waiting for our Part 145 facility to get back to us but maybe somebody of you has heard about this phenomenon:

2012 AS350B3e with a NAT AMS 43 TSO – ICS and as soon as the HORN switch engages, you hear a very high frequent tone in all headsets.

When you switch to pilot isolated, the pilot's headset goes quiet, everybody else still hears it.

This is also with headsets in the back (and/or copilot) unplugged.

When you disengage the HORN, it goes away immediately.

Switching to a Garmin GMA340H ICS could help :} but is not the favoured solution for the problem at the moment :E

Any ideas? TIA

[RVDT]

RTF,

I think your ICS may be OK.

I assume that there are no warnings and this is with the engine running at normal NR?

If on the ground and engine stopped you will have several warnings obviously.

No doubt you are aware that in the B3 you are obliged to have 2 functioning headsets ( Pilot and Co-Pilot) and ICS as per RFM Limitations.

The Pilot ISO is just doing as it should - isolate the ICS.

I would guess that your warning unit and/or sensor that talks to the warning unit is duff.

[Ready2Fly]

Hi RVDT
RTF,

I think your ICS may be OK.

I assume that there are no warnings and this is with the engine running at normal NR?

If on the ground and engine stopped you will have several warnings obviously.

No doubt you are aware that in the B3 you are obliged to have 2 functioning headsets ( Pilot and Co-Pilot) and ICS as per RFM Limitations.

The Pilot ISO is just doing as it should - isolate the ICS.

I would guess that your warning unit and/or sensor that talks to the warning unit is duff.

You are right, engine at flight idle and ready to depart. I did not test it with all the bells and whistles because you probably would not recognise it anyway. I did unplug the headsets to see whether it makes any difference.

Some people (i.e. older) might not even hear it as it is very high frequent tone and not very loud. It is clearly linked to anything which engages with the HORN switch and the warning unit is a good start...

Thank you for the hint. I will relay it ... and get back as soon as I know what it was.

[helimo]

hey guys I'm posting this again because we are still looking for an EASA certified EMS Kit for the 350/355 series. Used condition would be the best. Any ideas ?

[Gemini Twin]

Can anyone explain and define the meaning in Airbus service manuals of the following acronyms: OTL and SLL?

[Flyting]

Helimo
PM me... I have one for you

[Rigidhead]

Gemini,

OTL is "Operating Time Limit" for various items, such as T/R Driveshaft Bearings
Etc. These limits usually have an allowable margin for operational convenience.
The time limit may be in Hours or Calendar time.

SLL is "Service Life Limit" and is the ultimate allowable life of an item and has no
Margin allowed.

Regards,

Rigidhead

[John Eacott]

Some may find this table useful, but I hasten to add that I haven't checked it for accuracy!

http://www.eacott.com.au/gallery/d/7028-1/Squirrel+difference+table.jpg

[Gemini Twin]

Cheers RH. Some have explained to me that OTL's are recommended limits and not considered mandatory, but I don't think this is correct.

[Ready2Fly]

Hi RVDT

.
.
.

Thank you for the hint. I will relay it ... and get back as soon as I know what it was.

The warning unit output simply was too high. Reducing the output level via the poti helped to eliminate the problem.

[zippiesdrainage]

May be a simple mistake or oversight, in the flight manual it states that when experiencing a fire in flight to switch off the booster pumps, while the Eurosafety App that I have for my phone doesn't include this step. Is this a mistake in the app or has there been some revision in the manual or elsewhere that I can't find?

EDIT: Never mind. I contacted Eurosafety and it was told that it was a mistake in the app.

[Ian Corrigible]

Robertson Fuel Systems and Vector Aerospace to offer 'direct replacement primary fuel tank' for AS350, featuring "multiple safety enhancements including all new modernized fuel retention technology, new components and increased fuel capacity (567 L vs. 552 L)."

Vector to display AS350 primary fuel tank at Heli-Expo (http://helihub.com/2015/02/26/vector-to-display-as350-primary-fuel-tank-at-heli-expo)

I/C

[RVDT]

In June 2011, Vector Aerospace was acquired by Eurocopter Holdings, the holding entity of the Eurocopter Group and a subsidiary of global aerospace and defense giant EADS.

Somewhat circular argument?

[AlfonsoBonzo]

Does any of you fine people know if it is possible to get an EASA AS350 type rating outside of Europe? Somewhere were it might be a little cheaper than in the EU?

[adnanjaffar]

Having time to spare the other day, I was reading through 350's FLM. Being used to Bells and german side of EC's I was amazed at 350's rate of climb performance charts. Two charts, one for corrected weight and the other for rate of climb.

Why the corrected weight chart and what is the catch behind it?

Hi.. did you find answer to this question of urs?

[Cyclic Hotline]

Interesting report.

http://www.tsb.gc.ca/eng/rapports-reports/aviation/2016/a16p0045/a16p0045.asp

[paco]

It sure is! A phenomenon of any single-system helicopter? Outside the approved flight envelope? There would be a few pilots who would disagree with that.

[[email protected]]

Shock horror - wazzing and zooming at high AUM and speed to show off to pax often leads to disaster!

As discussed on this forum before, the 350 has exactly the same problems with servo transparency/jackstall as the Gazelle so its not like it should have come as a surprise to Airbus/Eurocopter/Aerospatiale.

Every Brit Mil helicopter pilot trained on the Gazelle will have been shown the entry to and recovery from jackstall/servo transparency exactly because it is dangerous.

[Thomas coupling]

I remember it well - even to this day. It was something the instructor showed us literally hours into flying a helicopter and it was very scarey.
Dive to near Vne (163kts I believe) and then pull firmly back on the cyclic:eek::eek::eek::eek:
I recall the Gazxelle lurching up and to the right (retreating blade side???). Completely out of control for about 1 or 2 seconds as it then automatically pulled itself out of Jackstall. The pilot then regained control.
I went on to teach it hundreds of times as an Instructor and loved doing it by then!
The MoD stopped it shortly thereafter because it was damaging the control runs.

I often wondered if anyone in civvy street came across this phenomena and until this incident never heard of anyone experiencing it.

Looks like a very very lucky man surviving this incident, so, too the pax:ugh::ugh::ugh:

[paco]

They are not exactly the same - the Gazelle is predictable - it is not necessarily so in the 350 as was found on several occasions in Canada. One of our guys had a run in with it on the ground.

[[email protected]]

One of our guys had a run in with it on the ground. how on earth did he manage that?

[Thomas coupling]

How do you get jackstall on the deck FFS? You need to be on the extreme edge of RBS for starters???

[paco]

He had a cyclic runaway during the preflight checks - he could bench press 180 lbs and couldn't stop it. Canadian helicopters had one too, though they didn't report it. Given that, to the French "servo transparency" means that the jack may as well not be there, to me that is a very similar effect (perhaps I should have said equivalent in the previous post). There have been reports of people getting it flying at 40 kts round a fire and coming off the top of a mountain. There is no way that the 350 version is as predictable as the Gazelle's, which does it every time, right on cue.

phil

[[email protected]]

Ah, so it was a jack hardover as opposed to a jack collapse (which is essentially what jackstall/servo transparency is) That makes more sense.

[paco]

If only they could get the translation right. I'm assuming that jackstall makes the controls rigid? But yes, hardover describes it better, though still similar to me. It makes the point that it doen't do to skimp on the hydraulic training for this beast....

[[email protected]]

No, the jacks collapse as the aerodynamic backloads from the rotor overpower the hydraulics.

Since the highest aero loads are on the retreating side, aft of the lateral position, it displays the same symptoms as retreating blade stall - ie a roll to the right and a pitch nose up.

Just like RBS, it is encountered at high AUM/high speed/harsh manoeuvring/ham-fisted piloting combinations.

On the Gazelle, it was demonstrated in a dive to VNE at MPS (168 kts with about 14.5 degrees of pitch) and still required a hard pull to get it in.

The other demo was in a hard left turn with a hard pull - never done in a right turn as you could end up inverted.

[Thomas coupling]

Ah - a servo runaway as opposed to aerodynamic forces overcoming the hydraulic input. Got it. Chalk and cheese, methinks.

[paco]

Yes, apologies for the mix up.

[[email protected]]

Paco, if someone of your extensive experience and knowledge had misunderstood it, it is no surprise that the knowledge of newer pilots in the industry is sketchy on the subject:ok:

[paco]

Yes, that's the disturbing thing! Constantly trying to battle myth and legend!

[albatross]

If only they could get the translation right. I'm assuming that jackstall makes the controls rigid? But yes, hardover describes it better, though still similar to me. It makes the point that it doen't do to skimp on the hydraulic training for this beast....

Jackstall does not make the controls 'rigid' you can still move them. (350D) It was discussed in the RFM. We used to demonstrate in training. It felt a little like a hyd. failure on a 206 until you recovered from the condition.
Perhaps someone with access to an AS350D RFM will be kind enough as to post the actual reference.
As an aside we had a new Astar pilot trucking along at max cruise who pushed the hyd. cut off on the 350D collective..He said it got really interesting as the beast pitched up and banked right in a most startling manner.

[oldbeefer]

The other demo was in a hard left turn with a hard pull - never done in a right turn as you could end up inverted.

On my QHI course, my instructor did just that and we did a complete roll back to wings level. Instructor change the next day!

[[email protected]]

Fortunately you didn't do that to me on mine!!!:)

[oldbeefer]

Once was enough!

[MitchStick]

From AS350B3e RFM

Maybe that's what you're referring to Albatross..

[[email protected]]

Where it says 'reduce the severity of the manoeuvre' it really ought to specify that if you have pulled up or rolled and pulled into a turn, you need to reduce the aft cyclic as the increase in G is what has overloaded the jacks.

[albatross]

From AS350B3e RFM

Maybe that's what you're referring to Albatross..

Not what I remember from the 350D but close enough.
Many moons since I flew and did training in the D.
Can't find my manual...it is buried deep in a box in the basement.
The 355 had a "limit light" (due to the dual HYD system ) to advise you had reached the G limit of the aircraft.
Thanks.

[[email protected]]

The 355 had a "limit light" (due to the dual HYD system ) to advise you had reached the G limit of the aircraft. They took that idea onto the 365 as well and it illuminated as the aerodynamic backloads compressed the stbd lateral jack (retreating side again) and made a microswitch there.

[Red Ant]

Anybody flying the AS350B3+ finding that the N1 limit changes with altitude? Manual gives it as 101.1% N1 take-off limit(5 minute limit) at Hp = 0 ISA.
I am hitting the N1 limit at 100.4% to 100.6% at around 7000-8000' PA & 20 degC.

Any info from the guys with high time on B3+ would be greatly appreciated,

[Jimmy.]

They took that idea onto the 365 as well and it illuminated as the aerodynamic backloads compressed the stbd lateral jack (retreating side again) and made a microswitch there.
Yes, 330 daN if I remember correctly. It also illuminates and "gong" for Ng and Q limits.

[GOMflyboy76]

I no longer have the manuals, so can anyone tell me please, AS350B3 Power check when you have "BAD" numbers, what are the parameters? (+/- %)

[JimEli]

I no longer have the manuals, so can anyone tell me please, AS350B3 Power check when you have "BAD" numbers, what are the parameters? (+/- %)

Insufficient information. 2B, 2B1 or 2D?

[MitchStick]

AS350B3 has a 2B, otherwise he would have said B3+ or B3e I assume

[JimEli]

AS350B3 has a 2B, otherwise he would have said B3+ or B3e I assume

To my knowledge, I don’t believe the ‘+’ was ever adopted as the official nomenclator, at least never in the US. The RFMs simply refer to the variants as “AS 350 B3 Arriel 2B” and “AS 350 B3 Arriel 2B1”. The current model designation is “H125”, however the RFM is still entitled “AS 350 B3e”. IMHO, in the US, the manufacturer has always clouded the differences to the point of it ostensibly being a contributing factor in several accidents.

[ApolloHeli]

To my knowledge, I don’t believe the ‘+’ was ever adopted as the official nomenclator, at least never in the US. The RFMs simply refer to the variants as “AS 350 B3 Arriel 2B” and “AS 350 B3 Arriel 2B1”. The current model designation is “H125”, however the RFM is still entitled “AS 350 B3e”. IMHO, in the US, the manufacturer has always clouded the differences to the point of it ostensibly being a contributing factor in several accidents.

Curious to read about the accidents you're referring to?

Here in Europe it's very clear;
If you look at the EASA Type Rating list, it uses the following names for each variant:
-AS 350 B3) - Ecureuil
-AS 350 B3 Arriel 2B1) - Ecureuil
-AS 350 B3e) - Ecureuil

The B3 Arriel 2B1 (a.k.a. B3+ for short) and B3e only require familiarisation training between them, the B3 requires differences training. If someone simply uses "B3", I think it's safe to assume they mean "B3".

P.s. I believe the "B3+" may have come from Airbus initially (similar to their use of + for EC135's). Even if it's not official, it is clear which variant it refers to and is shorter than writing "...Arriel 2B1" every time.

[JimEli]

Curious to read about the accidents you're referring to?

Here in Europe it's very clear;
If you look at the EASA Type Rating list, it uses the following names for each variant:
-AS 350 B3) - Ecureuil
-AS 350 B3 Arriel 2B1) - Ecureuil
-AS 350 B3e) - Ecureuil

The B3 Arriel 2B1 (a.k.a. B3+ for short) and B3e only require familiarisation training between them, the B3 requires differences training. If someone simply uses "B3", I think it's safe to assume they mean "B3".

P.s. I believe the "B3+" may have come from Airbus initially (similar to their use of + for EC135's). Even if it's not official, it is clear which variant it refers to and is shorter than writing "...Arriel 2B1" every time.

Are you aware the factory training manual refers to the AS 350 B3 Arriel 2B as the "B3 Mod"?

As for the accidents, here's a start:

All three B3 variants incorporate a FADEC and an identical red GOV caution light. The light, requires similar but different responses in the 2B1 and 2D, but completely different in the 2B variant. In the 2B, the pilot must manually control engine RPM via a twist grip after the red GOV light illuminates. The 2B was initially produced with a red mechanical “slider” lever used to unlock the throttle range above the flight detent. After numerous incidents involving misunderstanding/misuse, the manufacturer removed the slider and replaced it with an electrical solenoid that automatically allowed access to the increased range. However, the solenoid was unreliable, subject to seizing and demonstrated to the factory to overheat and fail after a very short period of time. The solenoid mechanism went through another re-design to address these additional issues. A resulting alert service bulletin imposed preflight requirements and limitations upon the aircraft. Throughout this process, a bewildering array of conditional revisions to the flight manual and emergency service bulletins, all which required cross-referencing created confusion among operators and pilots, many of which were never aware of them. The manufacturer has a habit of addressing design flaws via procedural changes (examine the dual hydraulic option to unravel another human-factors nightmare). Here are a few accidents (in no specific order) related to 2B manual governor operations from which you can draw your own conclusions:

Report #1 (https://app.ntsb.gov/pdfgenerator/ReportGeneratorFile.ashx?EventID=20060608X00715&AKey=1&RType=Summary&IType=TA)
Report #2 (https://app.ntsb.gov/pdfgenerator/ReportGeneratorFile.ashx?EventID=20041104X01758&AKey=1&RType=Summary&IType=LA)
Report #3 (https://app.ntsb.gov/pdfgenerator/ReportGeneratorFile.ashx?EventID=20001212X21898&AKey=1&RType=Summary&IType=LA)
Report #4 (https://app.ntsb.gov/pdfgenerator/ReportGeneratorFile.ashx?EventID=20140119X64330&AKey=1&RType=Summary&IType=TA)
Report #5 (https://app.ntsb.gov/pdfgenerator/ReportGeneratorFile.ashx?EventID=20030513X00645&AKey=1&RType=Summary&IType=GA)
Report #6 (https://app.ntsb.gov/pdfgenerator/ReportGeneratorFile.ashx?EventID=20020906X01541&AKey=1&RType=Summary&IType=LA)

[JimEli]

Curious to read about the accidents you're referring to?
...


Continuing the accident discussion you inquire about...

Historically, the manufacturer has a pattern of generating incomplete solutions for correcting flawed systems. How long did it take the factory to incorporate a simple guard over the ACCU TEST switch to prevent inadvertent activation? The ACCU TEST switch removes stored hydraulic pressure in the tail rotor yaw-compensator, significantly increasing the forces required to move the pedals. Incidentally, in many aircraft the ACCU TEST switch is adjacent or very near the landing/taxi light switches. And for years, the ACCU TEST switch was referred to as HYD TEST, which probably contributed to operator confusion. The manufacturer used both labels throughout the flight manual for many years.

See this accident report (https://app.ntsb.gov/pdfgenerator/ReportGeneratorFile.ashx?EventID=20041217X02006&AKey=1&RType=Summary&IType=FA), and this report (https://app.ntsb.gov/pdfgenerator/ReportGeneratorFile.ashx?EventID=20031112X01883&AKey=1&RType=Summary&IType=LA).

When the factory started to offer a dual-hydraulic option, it continued to obscure switch labels, compounding the confusion. The dual version removed the 3 accumulators on the main rotor servos, yet retained the yaw-load compensator in the tail. Thus, the function of the ACCU TEST switch was altered, but to this day, it retains the ambiguous label.

At the same time, the HYD CUTOFF (“yaw servo hydraulic switch, is also called the hydraulic pressure switch or hydraulic cut off switch in various Airbus Helicopters rotorcraft flight manuals” – FAA’s statement) switch on the collective head also changed function since it was now impossible to actually “turn off” the hydraulics. Further contributing to the confusion, is that the physical switch and their locations are identical to the single-hydraulic version.

In addition, the RFM was (and still is) written from the perspective of a single-hydraulic configuration. All of the dual-hydraulic information is contained in a brief supplemental chapter inserted into the back of the RFM. The supplement highlights changes to the operating procedures which must be incorporated into the manual’s runup, shut down and emergency procedures. Imagine flying NVGs on an EMS flight and asking the nurse, an FAA required crew member for off-airport NVG landings (?) to find the dual-hydraulic emergency procedure so you could review it?

Next followed a series of incidents/accidents in which it was believed pilots made procedural failures, by attempting takeoff with incorrect switch positions. These inappropriate switch configurations, and resultant loss of control were never alluded to in the RFM. Further exacerbating these flaws was the fact that the cockpit lacked a warning indication of the potentially grave misconfiguration.

See this accident report (https://app.ntsb.gov/pdfgenerator/ReportGeneratorFile.ashx?EventID=20140409X31907&AKey=1&RType=Summary&IType=FA), and this report (https://app.ntsb.gov/pdfgenerator/ReportGeneratorFile.ashx?EventID=20140630X31517&AKey=1&RType=Summary&IType=IA) the author is aware of additional related incidents which didn’t result in the creation of an NTSB report.

What followed next, was a failed attempt to address the design short-comings by publishing a series of communiques describing the functions of the dual-hydraulic system and the inadequate established procedures for preventing incorrect switch configuration. The result was the somewhat predictable, yet horrific accident at Frisco, Colorado.

See this accident report (https://app.ntsb.gov/pdfgenerator/ReportGeneratorFile.ashx?EventID=20150703X00859&AKey=1&RType=Summary&IType=MA).

Oddly, the immediate response to this accident was to change the runup and shutdown procedures via an emergency service bulletin. The altered procedures mandated a confusing series of page swaps to the RFM, which had the pilot now perform the runup check during shutdown. This has the extremely odd and useless consequence of performing a check of a critical system after the flight is completed. Subsequent revisions to the manual left operators confused as to it's proper arrangement. A follow-on “pen and ink” change to the RFM included the addition of the almost laughable statement, “The yaw servo hydraulic switch (collective switch) must be in the “ON” (forward) position before takeoff.” A command to a pilot which seemingly forbids him/her from making a switch configuration mistake!

The factory then modified the warning system to alert the pilot of misconfigured switches. However, the modification was only installed on new aircraft and offered for optional purchase to install on existing aircraft. The manufacturer finally designed a new mono-stable ACCU TEST switch which would prevent the incorrect switch configuration, and thus the heartbreaking saga of a human-factors nightmare is closed.

[ApolloHeli]

Thanks for the information guys - I hadn't known using the manual throttle in the B3 was an issue; seemed simple enough among the pilots I know here in Europe, but the learnings from those reports make for good reading and show even the red CWP procedures which appear simple on paper can be dangerous in the stress of a real emergency.

Anyway, as I said I was simply curious about the accidents relating to confusion between which type was being flown as was mentioned earlier. The main intent of my earlier post was to clarify the question from GOMflyboy76 below, which led to confusion over which variant they referred to:

I no longer have the manuals, so can anyone tell me please, AS350B3 Power check when you have "BAD" numbers, what are the parameters? (+/- %)

Per my initial reply, it's safe to assume he's talking about the B3.

[MitchStick]

To my knowledge, I don’t believe the ‘+’ was ever adopted as the official nomenclator, at least never in the US. The RFMs simply refer to the variants as “AS 350 B3 Arriel 2B” and “AS 350 B3 Arriel 2B1”. The current model designation is “H125”, however the RFM is still entitled “AS 350 B3e”. IMHO, in the US, the manufacturer has always clouded the differences to the point of it ostensibly being a contributing factor in several accidents.


So do you have the answer to the original question by GOMflyboy76 or not?

[JimEli]

So do you have the answer to the original question by GOMflyboy76 or not?



Yes.

Dependent upon engine version.

Two charts and a table are utilized to make the determination, there is no +/- %, a check is simply pass/fail. And there are two components to a complete check, TRQ and T4 margin. Furthermore, to my knowledge, under newer versions of the VEMD software, an INCORRECT check is always failure. With older versions of software, you can manually determine an allowance for an INCORRECT T4 MARGIN, but not an INCORRECT TRQ MARGIN. However, in all cases, when computing the EPC manually, one calculates a corrected T4 value. Beyond that, the conditions under which the check were performed are needed to help determine pass/fail.

Oh, and if there is an IBFS installed, it's RFMS probably alters the RFM procedure in some manner.

[MitchStick]

Yes.

Dependent upon engine version.

Two charts and a table are utilized to make the determination, there is no +/- %, a check is simply pass/fail. And there are two components to a complete check, TRQ and T4 margin. Furthermore, to my knowledge, under newer versions of the VEMD software, an INCORRECT check is always failure. With older versions of software, you can manually determine an allowance for an INCORRECT T4 MARGIN, but not an INCORRECT TRQ MARGIN. However, in all cases, when computing the EPC manually, one calculates a corrected T4 value. Beyond that, the conditions under which the check were performed are needed to help determine pass/fail.

Oh, and if there is an IBFS installed, it's RFMS probably alters the RFM procedure in some manner.


You kind of answered by not answering.
At least for me being a dumb pilot.

Lets make a practical example

torque tot margin 16.4% on a H125

what do I get from this? The more margin the better?

[JimEli]

You kind of answered by not answering.
At least for me being a dumb pilot.

Lets make a practical example

torque tot margin 16.4% on a H125

what do I get from this? The more margin the better?



The OP asked what to do for a failed check. My answer completely covered his options. Basic familiarity with the type would lead to an understanding of what I stated.
As for your contrived and incomplete example, you have a 16.4% margin. More margin is more margin. If you have ever looked at the charts in chapter 5 of the RFM you would fully understand what the margin represents. I would suggest duplicating a VEMD EPC using the charts. No explanation required.

[tandemonium]

JimEli,

Thank you for your input in this thread--getting me back in the books. I have digital versions of the B3e and 2B1 RFMs, but I can't find any differences for the EPs regarding yellow or red GOV lights. Are you seeing anything different? My source materials might be out of date.

Cheers.

[JimEli]

JimEli,
Thank you for your input in this thread--getting me back in the books. I have digital versions of the B3e and 2B1 RFMs, but I can't find any differences for the EPs regarding yellow or red GOV lights. Are you seeing anything different? My source materials might be out of date.
Cheers.

You are correct. In the latest versions of the "harmonized" manuals, the procedures are the same.

[kiwi_andy]

Can someone either explain to me (or point me to a reference doc) how the cycles remaining on the Power turbine are calculated, I believe there are 2 different methods/options?
Thanks
Andy

[helisdw]

Which engine are you operating (or going to operate) - Arriel or Lycoming?

The cycle counting methods vary a bit between each manufacturer. Also for Lycoming / Honeywell there can be different methods of cycle counting depending on which PT disc is installed in the engine.

[kiwi_andy]

Its a Super D2 so has the Lycoming engine. The part number for the PT Rotor assy is 4-141-290-18 if that helps narrow it down?

[wrench1]

Its a Super D2 so has the Lycoming engine. The part number for the PT Rotor assy is 4-141-290-18 if that helps narrow it down?
If I recall there is a Lycoming SL that provides two separate methods to count cycles. Unfortunately I no longer have access to any mx docs that may help you. Perhaps an email to Soley who owns the SD2 STC may get you a free copy of the SL?

[helisdw]

Service Bulletin LT 101-71-00-0002 contains all the information for LTS101-700D2 engine cycle counting and should be accessible via Honeywell's website.

There are two methods for working out the Ng cycles - Method 1 is simpler but it can only be used up to max 103.3 Ng and is also conservative so you may well not get all the cycles out of the engine. Method 2 is a bit more complicated as you have to count 'minor' and 'major' cycles (unless you have Gas Generator Disc 4-111-062-XX with Titanium Impeller 4-11-052-64/-65 installed which eliminates need for minor cycle counting).


Method 1:

each engine start = 1.1 operating cycle; each flight during that start ('flight' is defined as a landing / surface contact) = 0.2.
total Ng operations for each engine start = 1.1 + (landings x 0.2)



Method 2:

major cycle = max Ng attained between each start and subsequent shutdown (correlate with a table e.g. 96 Ng = 0.5, 97 Ng = 0.6, etc.)
minor cycle = difference between max and min Ng multiplied by number of operations in this range (correlate with a 'factor matrix' e.g. min 70 Ng to max 102.5 Ng = 0.2)
total Ng operations for each engine start = major cycles + minor cycles



Np also needs calculated for each flight - this is based on the maximum Main Rotor RPM and there's a table in the SB.


It's easy to see why electronic cycle counters are popular! Saying that, if you can eliminate the minor cycles from Method 2 then noting the max Ng and max MR RPM for each engine start isn't too arduous.

[kiwi_andy]

OK thanks very much for the explanation... I have downloaded a copy of the SB, but I prefer your explanation!
I'm looking to buy a machine and want to establish whether my expected service life will be limited by hours, or cycles.... need to do some maths!
Thanks again!

[helisdw]

@kiwi_andy No problem at all - glad it was of some help.

If you’ve got a specific aircraft in mind then it’s worth taking a close look at the Power Turbine and Gas Turbine components - different S/N of the same P/N can have varying cycle / hour limits (these should be listed in the SB).

Cycle consumption will certainly be influenced by the type of flying you’ll be doing - lots of heavy load lifting with large fluctuations between max and min Ng can rack up the cycles (unless you can get the disc / impeller combo that does away with minor cycles). Lots of short flights and multiple starts will also quickly eat into your cycles but this is probably true of most turbine engines! The other thing to consider is whether you are frequently going to have to spool down from flight idle to ground idle - this also constitutes a proportion of an Ng cycle and can add up by the end of a busy day.

[kiwi_andy]

thanks again for the further clarification, and useful info. I will ascertain what Gas Generator disk is fitted.
Without a cycle counter fitted, there may be scope for the accuracy of any previous operators correctly counting cycles to affect the real cycle count particularly if the operating environment is quite varied.

[kiwi_andy]

Where can I search an AS350 airframe number to see where it was registered (anywhere in the world?) prior to its current owner?

[wrench1]

Where can I search an AS350 airframe number to see where it was registered (anywhere in the world?) prior to its current owner?
ROTORSPOT - Rotorcraft Registrations Database (Worldwide) (http://www.rotorspot.nl)

[kiwi_andy]

Perfect thanks!