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Power Assurance Check

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Power Assurance Check

Old 26th Jan 2018, 19:21
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Power Assurance Check

How often do you perform a Power Assurance Check? As I know some aircraft do it every 100-150FH as a scheduled maintenance but I think the better way for engine trend monitoring is 10-15FH. What is your opinion? I am not sure but some FLM requires to perform PAC every flight day. I hope you might know more about it. This is quite inconvenient especially in HEMS missions.
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Old 26th Jan 2018, 22:10
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H145T2 every 25 hrs required, if that helps
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Old 26th Jan 2018, 22:17
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If your engines are succeptible to FOD or the operating environment makes FOD damage more likely, every day would be best for trend monitoring.... if you see a big jump in values you might have ingested something! U.S. Military helicopters often require one daily.
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Old 27th Jan 2018, 00:49
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Don't quite follow your question as most Part 135 ops define the when/where of these checks, at least on this side of the pond. Also while different OEMs can use different terminologies a power trend check is different than a power assurance check.

Without knowing your specific aircraft/engine here are some general points.

The ops I familiar with, EMS and Oil & Gas, use a daily power trend check depending on aircraft type. This is usually taken in cruise at a defined altitude and torque setting. The pilot would record OAT, TOT, and other data as required. It varied between aircraft models but served the same purpose.

In most cases a power assurance check is only used if the trend checks show a problem, a scheduled inspection as you mentioned, a post-maintenance requirement, or other similar event.

I don't recall any aircraft that required a daily assurance check unless it was operator specified. I've seen some external load guys do one pending conditions to see how the aircraft performed prior to flying a load in confined areas.

So it all depends on the circumstances.
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Old 27th Jan 2018, 03:04
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I seem to remember that the Bell 222 required an acceptable daily (before first flight) power assurance check prior to performing CAT A Operations, however I don't know of any other helicopter having a similar requirement although it does make good sense.
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Old 27th Jan 2018, 03:17
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Originally Posted by tomek_m22 View Post
... I am not sure but some FLM requires to perform PAC every flight day. I hope you might know more about it. This is quite inconvenient especially in HEMS missions.
Depending on the aircraft, not inconvenient at all. Just push a button and the PAC happens automatically.
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Old 27th Jan 2018, 03:35
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If You've a VEMD/FADEC then it's too easy, I do one every day, or every start to observe the trend. If it's manual calculations then I still try & do one a day during the cruise....watching for a change
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Old 27th Jan 2018, 08:35
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AW139 - Required prior to each Cat A departure but most companies operating PC1 do it before the first flight of the day only. Cat B operations require PAC every 50 hours. Daily checks will provide trend data that is very valuable for those operating in salt-laden atmospheres (offshore) or in sandy/dusty conditions.
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Old 27th Jan 2018, 09:55
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We check stuff to death in helicopters, logic, practicality and statistics take second seat to dogma. OEM’s cover themselves, regulators oblige. You can do a 15 leg Cat A operation after a morning PA check, but because the clock ticks past midnight you suddenly have to do another. Same could be said for all kinds of checks. Some AC are better with more sophisticated DECU/FADEC systems, but a really good system would constantly monitor PA in normal flying and advise of any deterioration. Second best is the push button in cruise type. In some future century the helicopter industry will follow the auto industry to OBDII type monitoring.
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Old 27th Jan 2018, 16:38
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To answer the question

The maintenance manual for the engine and or the PFM will clearly state under what conditions or at what times you should be doing power assurance checks. Various customers may have their own requirements but in lieu of those go to the books.
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Old 27th Jan 2018, 16:44
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The USFS, and some of our powerline customers require them every 10 hours. We can then show a trend and it "can" show impending problems.
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Old 27th Jan 2018, 19:44
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when the DOM said get it done ! Was nice in the S76 C++ as could be done in flight. Just took a photo and texted it over. It would not auto-sample in flight when super cold out. Nobody could ever figure out why.
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Old 27th Jan 2018, 21:09
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I used to do them everyday, as requested by the engineers, on our EC135.
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Old 27th Jan 2018, 21:25
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Originally Posted by MightyGem View Post
I used to do them everyday, as requested by the engineers, on our EC135.
According PFM it's required every 100 FH for CAT A ops...

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Old 27th Jan 2018, 22:39
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Hi Tomek

I can only offer my observations for the EC135 and 145T2 which as flying Bull and Skadi point out have a requirement for the power assurance check on an hourly basis but both also have a requirement for trend monitoring to be established if operated in cat A (class 1). The frequency isn't specified,to the best of my knowledge, but daily seems sensible because it is much easier for us more forgetful pilots to remember to do something every day rather than to note when the aircraft is going to hit its next ten hour anniversary!
For the EC145T2, the power assurance check is exactly the same as the trend check i.e. both are carried out at 70% torque (not very obvious if you follow the on screen instructions of the Helionix which just call for flight above Vy!)


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Old 29th Jan 2018, 05:39
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Thanks for many comments. You confirmed my opinion the more often the better trend monitoring but there is an optimization point what is the best interval... We perform PAC in interval 20-25FH on EC135 but wondering to do it quite more often. On EC135 we also have an option to do In-flight Power Check at 60% TRQ but as I remember only Power Assurance Check at 75% on the ground is required by EMM for trend monitoring.

One PAC takes about 8-12min - 1.5-2min stablization for each engine on the ground so it is quite a bit of time to do it daily I think. In the past stabilization was set at 1min for each engine but then we had many problems with enough time for stabilization which led to inaccurate results. The engineering team during data analysis had even problems to find the stabilization period in the check caused by windy conditions, unintended pilot moves, yaw etc. So we've increased the time and results are much better now.

How are you doing with stabilization and results accuracy for PAC on the ground? Especially those, who do it every day. Do you have similar problems?
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Old 29th Jan 2018, 14:21
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are we talking about the same EC135 ???
For Cat A ops Power Check is to be performed every 100 flight hours...

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Old 29th Jan 2018, 18:04
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Hi Jacek!

To be precised 100FH is FLM requirement for Cat A as you said. However, if we are going to do an effective trend monitoring definitely better way is increased PAC frequency. EMM recommends to do it every 10FH or less for trend monitoring purposes. The reason is early detection of engine problem or more accurate trend line for example. The more samples the more accurate really engine state I think

PS Probably the same heli
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Old 21st Aug 2019, 21:15
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Hi All,

can you please advise me if power assurance check should be performed as daily routine on Bell 206 and Bell 407? If so, then as a normal procedures or it is required by special operations like Cat.A or any improved hover performance?
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Old 21st Aug 2019, 21:51
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To summarize

You asked about power assurance, not trend or hit checks. 3 places to find this information. HINT: one of is not on this forum.

1. Aircraft maintenance manual- ask your maintenance provider

2. Aircraft flight manual or POH- read it yourself

3. Part 135 or customer operations manual or contract- again read it yourself

You can exceed these requirements if you and your boss agree. You don't want to get fired for being too careful and burning some extra fuel.
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