DynaVibe Blog

Why Statically Balanced Props Still Need Dynamic Balancing

Monday, March 14, 2016

A balanced propeller assembly is important not just for having a smooth flying experience, but also for the health and longevity of an airplane’s engine, instruments and airframe.  Statically balancing a propeller can help reduce vibrations, but to reduce prop imbalance-induced vibration to the minimum, dynamic balancing is recommended. 

This story of a Beechcraft Super Musketeer illustrates the importance of dynamic prop balancing, even after static balancing has been performed.  This Beech had a 200 horsepower Lycoming engine and a constant speed prop.  The airplane had long experienced a vibration problem, but the owner had never attempted to resolve it.  The airplane’s propeller was last statically balanced in 2000.

Even though a prop has been statically balanced, once mounted, things can change because the entire propeller assembly comes into play, not just the perfectly balanced, ready-to-mount prop.  

It takes just the slightest change in mass anywhere in the propeller assembly to change the balance and introduce a vibration.  These numbers illustrate this reality:  a perfectly balanced prop, offset by just .0005 inches during installation, can cause a vibration of .6 Inches per Second (IPS)!  This scenario occurs more often than most pilots or owners know, because many props don’t have an indexing mechanism to ensure that during mounting, the prop it is perfectly centered with the crankshaft.  The dynamic balancing process corrects these “coupling” errors that can result when mounting a prop.

In the case of the Super Musketeer, the prop imbalance was discovered when the owner brought it in for some maintenance.  The mechanic had access to a DynaVibe balancing system and did a quick prop balance check.  This check revealed a severe vibration of 1.5 IPS, well above the FAA specified maximum limit of 1.2 IPS for prop vibration.  A vibration of this magnitude mandates removal of the prop for static balancing.  The mechanic pulled the prop off and sent it to a prop shop for inspection and static balancing.  The mechanic and owner were surprised to discover that during the previous static balance from 15 years ago, the weight had been added to the wrong prop blade, making the balance and vibration problem worse, not better.  The owner had lived with this problem, simply assuming that some level of vibration is a product of combustion. 

After the static balancing was complete, the mechanic remounted the prop on the Super Musketeer and dynamically checked the balance.  The static balancing process had reduced the prop vibration by about half, to .67 IPS.  Using the weight solution provided during the initial dynamic balancing check, the mechanic added the prescribed weight where indicated and did a second balancing run, which showed the vibration had dropped to .04 IPS, well below the level that is discernible by the pilot or passengers.  The following report was generated by the DynaVibe GX2 and shows the results of the dynamic balancing runs, including the level of vibration detected and the weight solution calculated to resolve the detected vibration, and where to install it:

The owner’s feedback after dynamic balancing was that his Musketeer felt like a totally new airplane!  Static balancing, followed by dynamic balancing, is a great way to get a smoother flying experience and take stress off of the engine, instruments and airframe.  You can get similar results:  shop for DynaVibe in our online store, or if you have questions, please call us at 650.800.3092, send email to sales@rpxtech.com or enter your email address in the form below.  


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When Prop Balancing Isn't Enough: Troubleshooting Complex Vibrations

Friday, February 26, 2016

This webinar was part of the EAA webinar series and was originally broadcast on February 24, 2016.  It features RPX Technologies co-founder Matt Dock as presenter.


 

To learn more about using DynaVibe to dynamically balance your prop, or to conduct a vibration survey to pinpoint more complex vibrations, please call us at 650.800.3092 or by email:  sales@rpxtech.com.  If you prefer, enter your email address in the form below and we'll contact you! Shop for DynaVibe by visiting our online store.

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Video: Vibration Surveys with DynaVibe

Tuesday, February 23, 2016

There's increasing talk about vibrations surveys - what they are, why and how to do them - for good reason: vibrations damage aircraft. A vibration survey will allow you to pinpoint the source of a vibration so that you don't have to pay for speculative maintenance in an effort to resolve it.  We've written a lot recently in this blog about vibration surveys, and now we've done one better: we can show you the process in our new video!

We set up an RV-12 with a Rotax 912 engine for balancing and vibration surveying with the DynaVibe GX2, our dynamic prop balancer that also has vibration survey capability.  In just over three minutes, the video will show you the process sequence and sensor placement for collecting a vibe survey.  You can watch it here:

If you are new to the concept and practice of vibe surveys, please review some of our older posts that discuss this subject.  Even better, we welcome your inquiries on how and why to perform vibe surveys, and how to interpret the results you're seeing.  Feel free to call us at 650.800.3092, send email to sales@rpxtech.com or simply fill your email address in the form below to have us contact you.  To shop for a DynaVibe system, visit out online store.

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Airboat Balancing with DynaVibe

Monday, February 15, 2016

Props are every bit as critical to the performance of airboats as airplane propellers are to aircraft.  DynaVibe balances both equally well, as the principles of balancing don’t differ from airplanes to airboats.  The benefits are also similar:  less stress on the engine, the propeller, the mounts, instruments and hull.

Airboat propeller balancing with DynaVibe

Here are two stories of airboat prop balancing with DynaVibe.

An owner who had installed a modified 502 V-8 engine in his airboat experienced a problem on the 5-bladed prop he was using.  After just 10 hours of use on the prop, the blades cracked, resulting in a catastrophic failure.  Because the owner had balanced the prop at installation with DynaVibe, he had the diagnostic data to allow the blade manufacturer to rule out imbalance as the cause of the failure.  Instead, the manufacturer determined that there wasn’t sufficient blade surface for the horsepower of the engine: the powerful engine was spinning the blades too fast.  The manufacturer provided a new, 6-bladed prop at no charge to this owner.  The new prop was also balanced, going from an initial vibration of .65 Inches Per Second (IPS) to .06 IPS on the final run.  This owner shared, “It felt really good having the information from the DynaVibe balancing runs to go to the prop manufacturer on a warranty claim, which they quickly honored.”

Another airboat owner got help balancing his prop from a DynaVibe GX2 user.  This airboat was running a Whirlwind prop on a Chevy engine with a Rotator brand reduction, and it was experiencing a pretty bad vibration in RPM transition at about 1/3 power.  This initial balancing run revealed a severe vibration of 2.35 IPS, which after a series of balancing runs was reduced to .13 IPS.  The GX2 owner shared, “At the last weight addition, it (the vibration) cleaned up significantly.”  The following photo shows the balancing setup for this airboat:

An airboat prop set up for balancing with DynaVibe

DynaVibe owners can use their existing systems to balance airboats to get better performance and improve reliability.  To learn more about using DynaVibe to balance airboats, call us at 650.800.3092 or enter your email address in the box below and a DynaVibe team member will contact you.  Visit the online store to shop for DynaVibe.  We welcome your questions!


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Propeller Vibration Levels Guide

Thursday, January 28, 2016

Many owners and operators ask about what acceptable levels are for propeller vibration and what to do about it.  DynaVibe has prepared the following chart as a guide to understanding prop vibration and when balancing is recommended based on vibration levels:

Aircraft propeller vibration guidelines  

This chart is for information purposes only, and is not intended to replace, supersede or contradict any information in FAA Advisory Circular 20-37E which describes maintenance procedures for owners, operators and FAA certified maintenance personnel for aircraft propellers.  AC 20-37E is a great resource for field propeller maintenance, and it includes a very useful checklist for propeller annual inspection.

Dynamic propeller balancing is easily accomplished using the DynaVibe Classic, for simple balancing, or the DynaVibe GX2 to balance and complete vibration surveys.  The DynaVibe team is always happy to discuss balancing, vibration analysis and resolution, so please contact us if you have questions.  You can reach us by telephone at 469.708.8779, by email at sales@rpxtech.com or simply complete the form below and we'll contact you.  To get pricing or buy a DynaVibe system, visit our online store.

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Making Money with DynaVibe

Friday, January 08, 2016

Many repair stations and service centers are using DynaVibe to offer prop balancing and vibration analysis services, adding a nice revenue stream to their bottom line.  We’ve shared some of their stories on this blog:  KSFB Aircraft Maintenance Center, Stillwater Aircraft Services, Base Leg Aviation and Skywest Aviation to name just a few.

We’ve collected some insight from listening to how our MRO customers are using DynaVibe to let us share the good, better and best ways to use DynaVibe to boost service revenues, grow your business and create happier customers in the process.  Here is what we have learned:

Good

Simply adding “Dynamic Propeller Balancing” services to your menu of service offerings is a good thing.  You’ll gain some business specifically because some customers need their propellers balanced, and when they learn you offer these services, they'll come to you for them.  Promoting the fact that you offer prop balancing and vibration analysis (something the DynaVibe GX2 can do) will generate some new service revenue for you.  While this approach will generate some service revenue, it is a passive approach as it depends on the customer seeking a provider of these services.

Better

A better approach is to recognize that many owners and pilots don’t realize their prop could be out of balance, or that they have a vibration.  Paul Dye, editor-in-chief of Kitplanes Magazine, in a recent article wrote of this phenomenon of not realizing that over time, vibrations gradually creep in and grow, but go unnoticed.  We covered this phenomenon if a recent blog post, and we regularly hear from those who are amazed at how smooth their airplane is after balancing.  A better approach therefore is to ask every customer that comes in if they want their prop balanced while their airplane is in for service.  A surprising number of them will say “yes” particularly when they understand the benefits.

Best

The best approach, the one that serves the MRO and owner or pilot best, is to use DynaVibe to complete a free baseline vibration survey on every airplane that comes into the shop.  If there is a vibration, whether propeller imbalance induced or caused by something else, the vibration survey will show it.  DynaVibe produces reports that the MRO can share with a customer that show the magnitude and type of vibrations that exist.  When made aware of this information, most customers will want to have these vibrations resolved, and they often are through dynamic prop balancing.  Furthermore, the vibration survey is a great preventative maintenance tool, providing a historical record to compare to a new vibration survey the next time that airplane comes into the shop.

Repair stations, service centers and mechanics can maximize their service revenue using the “Best” approach with DynaVibe.  Furthermore, service revenue opportunities beyond prop balancing and vibration analysis exist.  Ascutney Air uses its DynaVibe system to also offer airplane tire balancing services as well.  To increase your service revenue with DynaVibe, visit our online store to buy your system.  If you have questions about how DynaVibe works or how to use it, please get in touch with us at sales@rpxtech.com, by telephone at 469.708.8779 or by entering your email address in the form below.    

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Interpreting Vibration Analysis Data

Tuesday, December 15, 2015

Pilots, aircraft owners, builders and mechanics are increasingly discovering the benefits of vibration analysis as a way to identify and resolve complex vibrations.  Spectral analysis, vibration analysis or vibrations surveys are very helpful in pinpointing the source of an elusive vibration or simply doing engine trend monitoring as a preventative maintenance approach. 

The DynaVibe GX2 is a prop balancer and vibration analyzer.  When you use it to perform vibration analysis, it detects and reports the various vibrations that are affecting an airplane.  For example, DynaVibe might detect a vibration that is occurring once per prop rotation – what is commonly referred to as a 1-per vibration.  There are also half-per, 1.5-per, 2-per and many other vibrations that can occur.  What do these vibrations indicate?

One way to find out what a vibration means is to contact the DynaVibe team.  We’re always happy to help customers understand how to use DynaVibe for spectral analysis and explain the results of a vibration survey.  We have also put together the following vibration table using the excellent material originally published by John Schwaner of Sacramento SkyRanch.  We hope you find it helpful, with the following disclaimer:  this data is for educational purposes only.  If your engine is exhibiting symptoms of vibration, properly rated professionals using diagnostic equipment should check it.

Table of airplane vibration orders with explanations

This table is a good place to start in understanding the cause of vibrations detected through analysis with the DynaVibe GX2.  If you would like to know more about vibration orders and causes, we can help.  Just reach out to us using the contact information or form below.

The DynaVibe GX2 is he most affordable full-spectrum vibration analyzer on the market.  To learn how to use DynaVibe for vibration analysis, enter your email address in the form below to be contacted by a DynaVibe team member.  To purchase a DynaVibe, visit our online store, or simply call:  469.708.8779.

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EAA Sport Aviation Article

Tuesday, December 08, 2015

RPX Technologies co-founder Matthew Dock contributed an article in the December 2015 edition of Sport Aviation - the Experimenter section (pg. 22) of the magazine: "When Prop Balancing Isn't Enough."

In the article, Matt discusses what to do when dynamic prop balancing isn't enough to eliminate a vibration. Click the cover image above to read the article! If what Matt describes sounds like a problem you're having, DynaVibe can help detect a vibration's source, so you can eliminate it.  

If you'd like to learn how the DynaVibe GX2 can help you troubleshoot complex vibrations, contact RPX Technologies by entering your email in the form below or simply call us at 469.708.8779

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Upgrade your DynaVibe Classic to a GX2!

Monday, December 07, 2015

If you're a DynaVibe Classic owner, RPX Technologies has a limited-time upgrade offer that can put a new DynaVibe GX2 in your hands.  The GX2 supports two accelerometers for simultaneous data acquisition, providing substantially more diagnostic capabilities than the Classic.  The GX2 is a prop balancer and vibration analyzer, and it is the technology platform into which RPX is building product enhancements. 

Here’s the short list of what you get when you upgrade from a Classic to a GX2:

ü  Automated prop balancing solutions. The Autobalance feature of the GX2 saves time, letting you balance in fewer runs, with increased accuracy and to lower vibration levels. 

ü  Vibration spectrum analysis.  When vibrations are not related to prop imbalance, the advanced diagnostic capabilities of the GX2 let you troubleshoot and pinpoint other, complex vibration sources.

ü  Full color report generation.  Save the reports the GX2 generates for record keeping or to give to customers, a very useful feature for mechanics, shops, repair stations and service centers.  These reports show propeller balance and vibration analysis details as well as customer and aircraft information.

Here is how to upgrade your Classic to a GX2:

1. Visit the RPX Technologies online store and purchase the Classic to GX2 upgrade (scroll to the bottom of the store page to see the offer). The cost is $2,995.  You’ll receive a $1,000 trade-in credit for your Classic. We’ll reuse your photo tachometer, accelerometer, and case, then provide you with a new GX2 system and 2nd accelerometer.

2. After you’ve purchased your GX2 upgrade in the online store, you’ll be contacted by DynaVibe and provided with a Return Authorization Number and shipping instructions.

3. Ship your entire DynaVibe Classic kit back to RPX Technologies per instructions. Once we receive it, we can usually turn your upgrade order around the same day.

All DynaVibe GX2 systems come with NIST certification, so you’ll have a new NIST certificate as well!

If you have any questions about upgrading your DynaVibe Classic to a DynaVibe GX2, just enter your email in the form below, or call us:  469.708.8779.


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Mitchell Flying Service Monitors Engine Trends with DynaVibe

Sunday, November 29, 2015

Matthew Mitchell operates Mitchell Flying Service, an agricultural aviation operator based out of Perry Municipal Airport (F22) in Oklahoma.  Mitchell has been flying since 1990 and puts about 250 to 300 hours per year on his Grumman Ag-Cat, for which he has two TPE-331 engines that he rotates as needed.  The rigors of agricultural aviation have shown Mitchell the value of keeping the prop on his Ag-Cat in good balance, which is done using a DynaVibe GX2

Anytime something changes with the prop, such as maintenance or mounting the prop after an engine change, Mitchell likes to have a dynamic balancing performed.  “It is essential to have the prop balanced,” states Mitchell.  Doing so eliminates vibration caused by propeller assembly imbalance, which reduces wear on the engine, airframe and instruments.  Dynamically balancing a propeller is an excellent preventative maintenance approach that can help eliminate future engine problems that might otherwise ground an operator.

Mitchell Flying Service

Another significant benefit to using the DynaVibe GX2 is the vibration survey capability it provides.  “DynaVibe checks other vibration ranges besides the propeller,” says Mitchell.  “It’s a good way to keep an eye on the engine, because you may not feel a vibration that DynaVibe can detect.”  Anytime Mitchell puts an engine together, he likes to have a baseline vibration analysis done.  This allows him to do trend monitoring on the engine with DynaVibe to monitor the health of that engine while it is in use.  Regular vibrations surveys can help operators like Mitchell to identify problems before they cause a shutdown or result in a failure.

The DynaVibe GX2 is a dynamic prop balancer and vibration analyzer that can improve performance and maintain engine health.  To get your own DynaVibe GX2, visit the RPX Technologies online store, enter your email address below or simply call us at:  469.708.8779.


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Questions? Contact us at sales@rpxtech.com