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Bell 206 85%TQ 82KT flight limitation exceeded


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#21 helonorth

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Posted 27 December 2017 - 10:51

Mike...I guess my avatar accolades are misunderstood. Cheif flight instructor/135 pilot probably should read Chief flight instructor for the flight school of our company/line pilot on charter/tour/film flight line. And therefore its been updated to reflect my experience more precisely. ;)

We have three companies in one, Charter/School/Maintenance The company Chief Pilot is the 135 Company Check airmen or lead check airmen. Also a DPE.

My reference to the issue at hand came from speaking to our DOM as well we have a close... very close relation with Bell. Sure there was an exceedence, never said not to speak up about it. I simply said no mention of what to do about it leaves your DOM at his own discretion on how to proceed.

Its like in school students read in their Robinson POH, blades must turn within 5 seconds of clutch engagement. So when it takes 8 seconds they shut her down and run in saying OMG!! we are gonna die cant fly it.

Yet in reality, there is a specific runout time Maintenance manuals give, and when within that limit the 5 second rule is overridden. No pilot knows this unless they read it themselves or are shown by Maintenance.

Sometimes certain limits are there simply to provide the necessary window for component life limits, not because its gonna explode on ya.

Serious limit exceedance occurrences are definitely listed with replacement and maintenance schedules. Calling your OEM everytime something is not listed is about as effective as going to WebMD for a diagnosis..your going to end up in the ER regardless...paper cut, sliver, broken bone...yet we have experienced life enough to know how to address certain issues. So has a well seasoned DOM.

Now that said, there are better ways to do things, such as power checks, and there are several ways to skin a cat. Some are effective and yield possitive results, some are effective and may cause damage too, some ways are just plain retarded.

My opinion from asking and learning from those that know more about maintenance and repair than I do, and trust based on how particular their standards are to begin with in all other areas of maintenance observed, the ship is most likely perfectly unharmed. But..retrain expected proceedures for future longevity concerns for the ships.

 

Just tell the guy to contact Bell if they can't find the inspection procedure in the maintenance manual. I would stop trying to down-play and explain away your previous bad advice.



#22 WolftalonID

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Posted 27 December 2017 - 13:12

I didnt down play anything I said. And he already has contacted bell. Who are you to come at me like that?
Sometimes we think we know it all....only later to discover we only knew all we had learned. Never stop learning.

#23 iChris

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Posted 06 January 2018 - 00:35

Im working for a company flying H125 B3e overseas. However they have one Bell 206 which I rarely fly. However while doing a recurrent training flight for the pilot who flys the 206 all the time I discovered that the power checks were being done at 90% TQ 6000PA in level flight, which gives over 100KT airspeed. Needless to say this practice has immediately stopped. We looked in the maintenance manual but couldnt find an unscheduled inspection for this exceedance of the flight limitation.

 

I have decided not to fly in this aircraft until I have a response from Bell tech rep that no maintenance action is required. This is a remote underdeveloped country so that may take some time.

My question is does anyone have experience with exceedance of this limitation? I was taught the limitation is because of mast bending at high TQ airspeed combinations.

 

There is no conditional inspection or other additional maintenance action required. What you’re experiencing is not new. This is one of those limitations which is unfortunately misunderstood and most often neglected especially during power checks. It’s a misleading limitation, the 80 KIAS, for some people and often misunderstood as a five-minute limit for airspeed too.

 

That 100kt works out to a 25% overage. However, at best, IAS is no better than 10% accuracy, so you’re somewhere between 90 – 110kt or 12.5 - 37.5% exceedance. Engineering has factored in exceedances and over torques into their inspection requirements and life limits.

 

The best you can do is document/log as follows:

 

1. How many times VNE exceedance were exceeded?

2. Time duration per exceed?

3. Type of operations?

4. Reason on why the VNE was exceeded?

 

Pass it along to Bell @ pselight@bh.com  They’ll give it a ticket reference number. Bell’s reply can then be documented together with your original request to ensure that all these issues were documented and the airworthiness of the aircraft was never in doubt.

 

These were short duration exceedances and in your case, it’ll probably stand as no conditional inspection or additional maintenance required.

 

Below as an exchange along the same line as yours…

 

 

To: Bell Helicopter Technical Support Group

 

Ref: Bell 206B3 Flight Manual, BHT-206B3-FM-1, Page_1-4 (See Attached)

 

Per a recent conversation with your Technical Support Group, I would like to request a more detailed explanation into the reasoning for the Airspeed limitation between 85 - 100% torque for the 206B3. There is no inspection, maintenance actions, or airworthiness requirements listed in the Maintenance Manual if this Airspeed limitation is exceeded. Moreover, there is much confusion to whether or not this limitation regards airworthiness, control characteristics, trim, or longitudinal stability issues.

 

An explanation that may or may not be true is, this limitation is about mast bending. The exceedance puts pressure on the mast, mast bearing and transmission components. 

 

Therefore, in order to eliminate such confusion and misconceptions, I would like Bell's explanation into the reasoning for the Airspeed limitation between 85 - 100% torque for the 206B3.

 

I thank you in advance. 

 

----------------------------------------------------------------------------------------------------------------------------------------

 

Dear Sir,

 

The airspeed restriction while in the torque takeoff power range is to limit torsional stresses on the mast, combined with bending moments which occur at airspeeds above 80 KIAS.  This limitation has been established to limit the rotor loads that increase significantly in that range. The loads induced at these power settings, over a period of time, may cause premature failure of drivetrain components.  This restriction also prevents flying with takeoff torque settings indefinitely. 

 

Best Regards,

 

Bell Helicopter
Product Support Engineering

Toll-Free:+1 800-363-8023

Office: +1 450-437-2862
Fax: +1 450-433-0272
pselight@bh.com

 

----------------------------------------------------------------------------------------------------------------------------------------

 

To: Bell Helicopter Technical Support Group

 

As a Follow-up question, what should you do if this limit is exceeded? should it be logged and after a given number of occurrences warrant some type of inspection or component replacement.

 

 

----------------------------------------------------------------------------------------------------------------------------------------

Dear Sir,

 

Please provide more detailed information about the VNE exceedance limitations that may have been exceeded.

  1. How many times these VNE exceedance were exceeded?
  2. Type of operations?
  3. Reason on why the VNE was exceeded?
  4. S/N of the helicopter?

Best Regards,

 

Bell Helicopter
Product Support Engineering

Toll-Free:+1 800-363-8023

Office: +1 450-437-2862
Fax: +1 450-433-0272
pselight@bh.com

----------------------------------------------------------------------------------------------------------------------------------------

 

To: Bell Helicopter Technical Support Group

 

This is a general question on why airspeed exceedance doesn’t have any recourse action in the flight manual or maintenance manual. This was a question asked by an FAA inspector during a recent flight evaluation. Our answer was there’s no written actions specified or documented by Bell.

 

The FAA inspector suggested that we should log each occurrence and report them to Bell for further guidance. The FAA inspector was familiar with the 80 kts. max between 85 - 100% torque limitation being violated by a few flight training schools using the Bell 206, mostly low time flight instructors and student pilots. 

 

 As a theoretical, what should we do if given the following:

 

1. 15ea VNE exceedance during the last year, airspeed 90kts. torque above 90% but less than or equal 100%, 3-5 min each occurrence 

 

2. During level flight conducting engine power checks, trying to obtain highest torque level

 

3. Pilots unfamiliar with correct engine power check procedure.

 

----------------------------------------------------------------------------------------------------------------------------------------

 

Dear Sir,

 

Thanks for providing the feedback and answers on the questions from our previous email.

 

At this time, there is no conditional inspection or other additional maintenance action required for when the 80 kts. max between 85 - 100% torque limitation is not observed by the pilots.

 

You may report this condition to Product Support Engineering (PSE) if it occurs during operation as mentioned by the FAA.

 

Best Regards,

 

Bell Helicopter
Product Support Engineering

Toll-Free:+1 800-363-8023

Office: +1 450-437-2862
Fax: +1 450-433-0272
pselight@bh.com

 


Edited by iChris, 06 January 2018 - 02:12.

  • Wally, Fred0311 and WolftalonID like this
Regards,

Chris

#24 Eric Hunt

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Posted 07 January 2018 - 04:41

Some good plain answers there, Chris, well done.



#25 Nearly Retired

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Posted 09 January 2018 - 01:48

You may report this condition to Product Support Engineering (PSE) if it occurs during operation as mentioned by the FAA.

 

 

...Or you may not. Your choice.



#26 Whistlerpilot

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Posted 01 March 2018 - 19:39

The Bell tech reps response was pretty much as iChris described. In the end some numbers were exchanged and the power check is now being done as it should be. Lucky for me I don't need to fly this aircraft often. On my way to the Bell factory March 12 for the 505 course. The company is buying 2 505's though the B3e is still the aircraft of choice for high altitude flying in Nepal. There is competition for the "bottom" end of the market and for some strange reason my company wants to spend outrageous money for the 505 rather than just using a cheap B2. So I will keep you all posted on flying the 505 in the Himalaya. Too bad the Van Horn tail rotor isn't STC'ed yet but perhaps with that long tail boom the tail rotor has some oomph. Good times Pheriche, Dingboche, Lukla, Kathmandu shuttles. Everest Base Camp will be a little beyond what it can do.
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#27 WolftalonID

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Posted 02 March 2018 - 09:37

WP, if you want some early feedback on the operational performances of the 505 at altitude, email Mark Taylor over at Rocky Mountain Rotors in Montana. He has been flying one this last year around the area, upto and around the 10k ft altitudes. He has some great comparisons from his 407 and 206b3.

I have not flown the machine myself, but the feedback has been interesting to learn so far.
Sometimes we think we know it all....only later to discover we only knew all we had learned. Never stop learning.




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