Air2 innovated the provision of helicopter-assisted utility construction and maintenance services for extra-high voltage (EHV) transmission lines throughout North America. The company maintains and flies a fleet of MD 500 helicopters with pilots, crew, and mechanics that are highly trained and specialized for the work they do.
The high voltage power lines the crews at Air2 work on are too in demand to take out of commission for repairs. The Air2 team flies their helicopters into very close proximity to these lines, taking advantage of a thorough understanding of the properties of electrical transmission. The same properties that allow birds to land on power lines without getting electrocuted allow Air2 crews to do their important work, actually transferring linemen from the ship to the line while in hover just feet away from the line. It’s a process you must see to fully appreciate:
Given the critical nature of the work that Air2 does, keeping its ships maintained and in proper track and balance is essential. Tim Galeotti is an Air2 mechanic who helps maintain the eight-ship fleet. Performing regular track-and-balance procedures is part of the maintenance routine. “Well, track and balance, of course, affects the whole aircraft,” says Galeotti. “The closer you can get that reading or vibration down to none in the aircraft, of course, extends the life of your aircraft parts.”
Before acquiring a DynaVibe GX3 with the DynaTrack optical blade tracking accessory, Galeotti had access to two track-and-balance systems from different vendors. Both of these systems had their limitations and both were complicated to use. One broke frequently, and the software on the other one was unreliable. Given the importance of the track-and-balance procedure and the frequency with which Air2 does it for their fleet, having reliable track-and-balance gear is important. Another important factor is gear that is easy to use and allows mechanics to complete the process quickly, “because time is money,” states Galeotti.
Having used other track-and-balance gear, Galeotti was impressed with how easy it was to perform the main rotor track and balance on the MD 500 using DynaVibe with DynaTrack. “I was quite impressed because I've used several other devices,” said Galeotti. “What I found really nice was how user friendly it was. I mean, you didn't have these multiple buttons you had to push to get your result, and all we need is a clock angle, its reading; then, we can just plot it out on a chart. Also, with the tracker, it was nice to show exactly how to move that blade up and down in terms of how many inches or half-an-inch, or whatever you need to do.”
One reason the DynaVibe system with DynaTrack is easy to use is because you don’t need another person to hold, aim, and operate a light gun to do blade tracking. A single person can do everything needed to capture accurate readings. The DynaTrack optical blade tracking accessory attaches to the inside of the ship’s windscreen via a suction cup. The pilot or mechanic simply presses the “push-to-talk” button to measure one or two channels of vibration plus blade track, logging results from up to eight flight conditions per flight. “Holding like a gun... it's hard to hold there and get that image,” says Galeotti about the gun tracking systems he’s used, “but this [DynaTrack] here just takes it. I like that.”
The DynaVibe GX3 and DynaTrack is portable, allowing Galeotti to take the system anywhere the ships go, enabling the track-and-balance procedure to complete even in the field. “It's one of the simplest devices I ever used, and the smallest and lightest. In comparison to others I've used, it's top-rated I'd have to say. For the money that you spend on that, in comparison to others, you all have a product which is cheaper and works better.”
RPX is experiencing record sales for its helicopter track-and-balance kit. The helicopter community is responding enthusiastically to the solution’s ease-of-use and affordable price.
As we work with customers to help them obtain and use DynaVibe with DynaTrack to perform track-and-balance procedures, we get lots of questions about how our system works. This post will share a collection of questions we routinely get, with our answers. If you have questions or want more information about how to track-and-balance your ship, please contact us!
Q: What is the difference between DynaVibe and DynaTrack? Do I need one or both?
A: The DynaVibe GX3 is the handheld system that enables dynamic balancing, vibration analysis, and track-and-balance. An optical tach (a.k.a, phototachometer or phototach) attaches to the GX3 to measure RPM, as do one or two accelerometers to measure vibration magnitude. DynaTrack is an optional optical blade tracking GX3 accessory that enables blade tracking. A complete track-and-balance kit consists of a DynaVibe GX3 (which includes the optical tach and accelerometer) with DynaTrack.
Q: Is the DynaVibe and DynaTrack kit suitable for track-and-balance of 3 or 4 blade helicopters?
A: Yes. The kit will let you work with helicopters that have up to 6 blades.
Q: How big is the system?
A: The DynaVibe GX is a handheld system, as the photo shows, it is small and highly portable, easily used in the field.
Q: Are the accelerometers used by the DynaVibe system permanently fixed to the cables?
A: Yes, the DynaVibe accelerometers and cables are a single, fixed unit. We are aware that competing track-and-balance systems use accelerometers with detachable cables. We know that this question expresses a concern about having to replace the entire unit should a cable get cut or damaged. The good news for our customers is that a complete DynaVibe accelerometer and cable costs less than a cable for our competitor's track-and-balance system! RPX has the most affordable solution for doing track-and-balance.
Q: Does DynaTrack measure the main rotor rpm?
A: The main rotor RPM is measured by the optical tachometer attached to the DynaVibe GX3. The DynaTrack (also attached to the DynaVibe GX3) measures the blade track error.
Q: Does the DynaVibe GX3 system have an input for a magnetic pickup?
A: No. DynaVibe uses the industry's state-of-the-art optical tachometer. This approach is better because it is sometimes difficult to make proper adjustments with a magnetic pickup.
Q: How we can install the optical tachometer in, for example an AS350 helicopter? Should it be placed vertically to the blade or at some angle?
A: This photo shows the setup of the DynaVibe optical tach and accelerometer on an AS350. For most applications, the optical tach is mounted near the transmission and detects a strip of reflective tape on one of the blades grips.
Q: You state that your system can collect up to 8 flight condition reports. How are those condition reports saved? Do I have to clear the SD card where they are stored after every set of measurements?
A: You can get readings (IPS, phase, and track) for up to 8 different conditions per flight. These conditions are per the manufacturer's procedures, or whatever conditions you choose. Once you have completed a flight, you can review all of the conditions for which you captured readings, whether just 1 or all 8. When you begin a second flight, the new flight data will copy over the first flight data. You can go to the track log to review the data you’ve captured. You do not have to manually clear that data for a new flight and new data collection.
Q: Can you tell me about the Push-to-Talk button? What is its purpose?
A: The PTT button is what lets you do pilot-only data collection, if needed. It enables unit operation with a remote (in-cockpit) PTT switch so you do not have to hold the unit or push its buttons to capture readings. This allows for single-person operation, letting a pilot collect that data while concentrating on flying the aircraft. Using DynaTrack does not require two people.
Q: For what helicopters do you have Application Notes?
A: RPX has already published application notes for Bell 205, 206, 407, OH-58, EC350; Hughes 300, R22, R44, and Rotorway. We are regularly completing new Application Notes. Keep in mind that an Application Note is not required to use DynaVibe for track-and-balance on a helicopter, but it is helpful for installation and operation purposes. RPX Application Notes follow the manufacturers recommendations for track-and-balance, so if you have the maintenance manual and corresponding balance charts, you have what you need to track-and-balance using the system.
Q: Can you tell me about calibration? How long does it take?
A: A new DynaVibe GX3 unit comes already calibrated. As with many aviation tools, annual NIST-traceable certification is required for tools used on certified aircraft. For the DynaVibe GX3, recalibration costs just $249 USD. To have it recalibrated, just contact us for an RMA number and then send the unit and accelerometer(s) to RPX; there is no need to send the entire kit. We can complete a recalibration in one day, not including the shipping time.
Q: What kind of guarantee or warranty covers DynaVibe and DynaTrack?
A: We provide a money-back guarantee for the first 30-days after purchase. If you’re not satisfied with the system, you can return it for a full refund. A limited, lifetime warranty covers the purchase of new DynaVibe GX3 systems and DynaTrack accessories. Other accessory items are covered for a one-year period.
Q: In which format is the output file that contains the measurement data?
A: DynaVibe provides its output in the form of an HTML document, so no proprietary software is required to view the data, and it is easily shared.
Q: Are DynaVibe software updates available for free?
A: Yes. Software updates are free and obtained on the support page of the RPX website.
Q: Is it possible to review a User’s Manual for this device?
A: Yes. To obtain one, simply contact us through the website, by email or telephone and we will send you a free, current copy.
If you have other track-and-balance questions, please contact us!
RPX Technologies announces that its DynaVibe and DynaTrack optical blade tracking accessory have been accepted by the Robinson Helicopter Company for R22-series and R44-series helicopter tracking and balancing purposes.
During the 2018 HAI Heli-Expo, RPX personnel will demonstrate DynaVibe and DynaTrack in booth C4043. This complete track and balance system is simple-to-use, allows users to complete the process quickly, and is priced at less than $7,000 making it the most affordable track and balance system on the market.
RPX provides application notes specifically for Robinson, and the DynaVibe system has built-in setup information for R22-series and R44-series helicopters, streamlining the track and balance process.
“I have used the DynaVibe multiple times to adjust the Robinson R22 track and balance of the main blades, balance the scroll/squirrel cage fan and balance the tail rotor,” stated Mark Young of Tropic Airpower. “I actually got the tail rotor to 0.00 IPS with the DynaVibe. It is very easy to set up. I love the option of being able to take multiple readings per ground run and in-flight checks. Keeping the track and balance correct ensures good reliability of all components on the helicopter. This is a great instrument; I’m very satisfied over all.”
To learn more about using DynaVibe and DynaTrack with your R22 or R44-series Robinson helicopter, contact us using the yellow tab below.
An ounce of prevention is worth a pound of cure. This adage certainly applies to aircraft preventative maintenance. Take, for example, significant main rotor imbalance: it’s relatively easy to detect, because the pilot can often feel the vibrations from the imbalance in their back or the seat of their pants. This sensation usually prompts some preventative maintenance, before there is significant damage to components and impact to the bottom line.
With something like a tail rotor or fan wheel imbalance, however, the vibrations are rarely identifiable in the cockpit. Fatigue cracks and an unplanned out-of-service ship may be the first, obvious sign that something is wrong. What follows is a repair that is often time-consuming, expensive, and rarely conforms to your schedule. It’s more cost-effective and operationally efficient to invest in preventative maintenance than to repair damage.
Balancing fans are an aspect of preventative maintenance that can save expensive repair bills. For instance, consider the Robinson R22, where Robinson documentation states that “Fan balance must be checked upon installation; fanwheel imbalance can cause damage.” As the accompanying photographs show, this damage often reveals itself in the form of fatigue cracks in the engine cowling, requiring expensive repairs.
With the proper diagnostic equipment, such as the DynaVibe GX3 dynamic balancing system, checking for fan imbalance becomes a relatively simple procedure. You can use DynaVibe to objectively measure whether the fan wheel has a significant imbalance that may slowly but steadily be creating a fatigue-crack time bomb. A fan wheel vibration check is done with the same accelerometer and optical tach used to balance the main rotor, by simply moving the optical tach and left accelerometer to the fan, with the accelerometer typically pointed toward the centerline of the fan rotation as shown (the DynaTrack optical blade tracking accessory is not required for this procedure). Because in-flight aerodynamic factors are not involved, the entire procedure is typically done using ground runs exclusively, without hover or flight runs.
If the analysis shows that the fan is outside of the acceptable balance parameters, the DynaVibe system will step you through the balancing procedure. Follow the helicopter manufacturer's procedures. It may be helpful to refer to the RPX supplemental DynaVibe user manual and helicopter-specific application notes to assist with DynaVibe setup and operation.
Select the "Contact Us" link near the bottom of this page to discuss fan balancing with an RPX representative or to learn more about RPX helicopter track-and-balance solutions.
As a provider of dynamic prop balancer, aircraft vibration survey, and helicopter track-and-balance systems to the aviation maintenance industry, we meet a lot of great people who are interested in high-quality maintenance work while minimizing maintenance costs. Our experience has revealed a maintenance procedure where cutting corners can be costly: making helicopter trim tab adjustments. Here are some tips about this procedure that may prevent wasted time and unnecessary expense.
Tip 1: Use High-Quality Trim Tab Gauges
Helicopter mechanics need high quality trim tab gauges and, in some cases, the gauge is specified by the manufacturer for a particular blade set. The best trim tab gauge designs for most rotorcraft blades utilize dial indicators on a frame that attaches to the blade in a very repeatable way. These types of trim tab measurement instruments support accurate and reproducible measurements of the blade tab position.
This trim tab measurement reproducibility is critical when it comes to tracking blades. Before making any adjustments, the mechanic should verify that the same measurement can be made repeatedly. The mechanic should be able to put the trim tab gauge on the blade, make a measurement, remove the gauge, and repeat this sequence two more times, obtaining the same position result every time. If the measurements aren’t repeatable, the mounting technique should be reviewed and the tool should be checked to verify that it is functioning properly, and that it is the correct one specified for this blade set. Verifying that the gauge readings are reproducible before making the first tab adjustment can save many hours later.
In addition to reproducibility, trim tab measurement accuracy is also important because incredibly small adjustments can affect forward flight vibration. For a Robinson R22, a 0.015” tab adjustment can produce almost a quarter of an inch change in blade track. This is more than enough to cause a noticeable increase (or decrease) in vibration.
Tip 2: Use Recommended Tools for Tab Bending
Use the recommended tab adjustment tool when bending blade trim tabs. A lot of improper tools are used to make adjustments, from vice grips to sledge hammers (really). It is extremely important that the manufacturer’s recommended tools are used to adjust trim tabs and keep in mind that a tab bending tool appropriate for one set of blades may be the wrong tool for a different set of blades.
Robinson trim tabs, for example, should not be adjusted by simply applying torque to the tab about the tab’s root. Robinson trim tab adjustments are produced by more of a curling action resulting from three precisely applied forces that are generated by Robinson’s tab bending tool as shown below.
If tabs are bent improperly, the result can be costly. For instance, one mechanic thought that the trim tab on a Robinson was adjusted just like many other blade tabs, simply by bending the trim tab down. After a couple of flexing adjustments using the wrong tool, the rotor blade responded with a loud pop and an expensive replacement bill. There is a reason that Robinson sells a custom device for adjusting their trim tabs.
An underlying question for both of these tips is: how can you know the proper adjustments to make to helicopter trim tabs? The answer is given by the blade offsets measured by the DynaTrack, the vibration measured by the DynaVibe accelerometers, and the procedures in the helicopter manufacturer’s maintenance manual. However, if the mechanic doesn’t have the correct tab bending tools and trim tab gauges to make these adjustments safely, precisely, and accurately then the process will take longer at best and could be a costly mistake if the tabs are bent improperly.
Select the "Contact Us" link near the bottom of this page to learn more about RPX helicopter track-and-balance solutions.
DynaVibe with DynaTrack Simplifies Track-and-Balance for Sheriff Department's Helicopter Fleet, Improving Maintenance and Pilot Comfort
Whether you’re maintaining a fleet of helicopters or a single ship, blade tracking and balancing shouldn’t be a full-time job. When you do pull out your tools to do your next track and balance, will the tools complicate the task, or simplify it? RPX Technologies recently spoke with the mechanic for a county sheriff aviation unit in the southeast U.S. about the right tool for the job and how switching to the DynaVibe GX with DynaTrack made his job easier.
The department had previously purchased a competing track-and-balance system, but this mechanic shared that “I'd go for long periods of time and we didn't have to do a track and balance, and then you kind of relearn it every time you do it.” The mechanic recalled that the competing system “was way smarter than I was and a little more complicated than I was used to working with. I struggled through using it a few times and at one point, I contacted manufacturer for a field rep to come and help me again. They were willing to do it, but they were going to charge us an extreme amount of money to do that, to train us. That's the time I figured we needed to start looking at something a little less complicated.”
The DynaVibe GX3 balancer when coupled with the DynaTrack optical blade tracking system is efficient, accurate, affordable, and easy-to-use to perform helicopter blade track-and-balance. “We purchased a DynaVibe system,” noted the mechanic. “It's easy to install and set up. To operate it… probably took me less than an hour and 45 minutes to get everything done.”
His first use of the DynaVibe balancer was on a ship where the crew had just changed out the main rotor hub. During the initial track and balance process, he found that “the vertical wasn't too bad, but the lateral vibrations were pretty bad,” explained the mechanic. “After I made the PC link adjustment to bring the blade down, that helped the lateral quite a bit. And then on the second run after that, the DynaVibe system told me that I needed to add weights to the blank blade bolt and I did that. You could feel it just getting better on each run. I was impressed. We finished tracking it out and I was really happy with the way the system works.”
The department has multiple OH-58 helicopters and the mechanic’s goal is to always have at least two aircraft available for flight operations. As important is ensuring the helicopters are not degrading the ability of the crew to function. “There's always a primary and a backup aircraft,” explained the mechanic. “Our guys fly missions and they'll do orbits over the target area, and they fly three to four hours a day sometimes. It's easier on them, when they're not getting beat to death by the aircraft being out of track, and it's easier on the aircraft too.”
This mechanic summarizes his experience using DynaVibe and DynaTrack: “I’m really happy with the way the system works and everything. The RPX rep called and checked on me to see how my progress was, and we sat and talked about the readings I was getting and everything. I'm real satisfied with the service. There’s a great support system there for the customer, and that's a good selling point for these systems. Kudos to the DynaVibe guys; they’ve got a good product.”
Visit the Rotorcraft section of the RPX online store, or click the yellow "Contact Us" tab below to learn more about helicopter track-and-balance solutions.
Proud owner of a Jet Exec (turbine) RotorWay helicopter, Joseph Luiz completed his build in late 2017. In attendance for the 2015 EAA AirVenture fly-in convention (Oshkosh), he scoured the grounds to find an affordable, easy-to-use track and balance system for his RotorWay copter. Joe states “I went to Oshkosh with a mission; I went to every single booth that was providing this type of equipment because I needed something that worked flawlessly and provided peace of mind."
Before acquiring a track and balance solution, Joe had an unsuccessful attempt to balance the high-speed tail rotor on his RotorWay. “I ended up bending a shaft because I really didn't know how to properly balance.” At AirVenture, Joe visited the RPX Technologies booth where he discovered and bought a complete DynaVibe system with the DynaTrack optical tracking accessory. The DynaTrack simplified the helicopter track and balance with built-in setup information specifically for his RotorWay, as well as a compiled database of other helicopter systems.
Joe is using DynaVibe and DynaTrack to perform dynamic main and tail rotor balancing, as well as blade tracking. “It's been very simple and easy to use. With rotorcraft, you've got all this dynamic action occurring in unison, so it has to be just right. There is truly no margin of error, and I found DynaTrack helps eliminate that error.” He was able to track and balance his RotorWay’s main blades in a hover with one reading and one slave blade adjustment. DynaTrack representatives recommended that he begin the process by doing a hover track to make an initial assessment: “I did the readings and found I was three quarters of an inch out on my slave blade. I consulted the documentation, and it looked like I needed to make a pitch change on the slave blade to bring it down to match the master blade. I made a half turn on the slave blade and brought it within a tenth of an inch, and it was a night and day in performance. It was amazing, and I did that with one measurement! The change in performance and vibration levels was just phenomenal.”
Joe continues to use his DynaTrack to achieve optimal performance. “I'm flying, and I'm doing my dynamic main rotor blade tracking right now using the DynaTrack.” Joe also uses the DynaVibe system to balance the tail rotor. The result is a smoother flight and peak performance. Eliminating the vibrations that come from unbalanced or out-of-track rotors also reduces stress on the airframe, engine, and instruments. “For the amount of money that I spent and the functionality of the equipment, it was a no-brainer. The price was important to me because I'm not in the business of doing this. I wanted to get the best equipment I could without breaking the bank. Overall, I'm very satisfied with the equipment.”
His advice to fellow builders and/or owners? “Don’t beat around the bush on this one, the DynaTrack will ultimately save you thousands of dollars in prevented misbalances, provide optimal performance, and ensure peace of mind in its use. Simply put: just buy it.”
Learn more about DynaTrack by clicking on the yellow, "Contact Us" tab near the bottom of this page.
Using DynaVibe to Balance Rotorcraft
DynaVibe can balance rotors as well as propellers, and key to accurate rotor balancing is proper placement of the lateral and vertical accelerometers as well as the phototach sensor.
Lateral Accelerometer Placement
The purpose of the lateral accelerometer is to measure the mass imbalance that occurs once per rotation (1-per) of the rotor. The best way to measure the mass imbalance is to maximize the sensitivity to the mass imbalance while minimizing sensitivity to other vibrations.
To do so, mount the lateral accelerometer as high as possible on the rotor mast to maximize sensitivity. It’s also preferable to mount the accelerometer on a rigid structure. If the accelerometer is mounted on a bracket or other secondary structure, that structure may absorb vibration or modify the signal due to structural resonance. Furthermore, to maximize sensitivity, orient the accelerometer so that it is sensitive to the axis of minimum rotational inertia. For rotorcraft, this is usually the roll-axis, hence the reason for laterally mounting this accelerometer.
To minimize non-mass vibrations, point or align the accelerometer through the rotor shaft. If the accelerometer is mounted ahead of or behind the main rotor mast, then the accelerometer will receive vibration from the main rotor imbalance plus vibrations from any torsional vibration. This occurs frequently in analyzing engines: the vibration signature will change if the accelerometer is not pointed through the rotating element.
When measuring mass imbalance, a key area of focus is measuring the vibration when there is minimal forward airspeed. If the two blades are not identical in lift and drag, then blade asymmetry will cause a 1-per vibration. Measuring the mass imbalance at high forward speeds will cause the sensor to register both the mass imbalance and blade asymmetry. For this reason, it is best to collect mass imbalance data while in a step decent, power off.
When the lateral accelerometer and phototach are setup correctly, and the forward speed component of the 1-per vibration is eliminated, then balancing the rotor is just like balancing a prop.
Phototach Sensor Placement
Position the phototach so that it has a clear view of the rotor system, making sure that it is at least six inches away from the reflective tape target to get a good signal. A piece of reflective tape is applied to rotor system so the DynaVibe computer can determine the relative position of the blades to the vibration signal received by the accelerometer. The phototach position is determined by the polar charts that you will be using, the manufacturer's recommendation, or by talking with a DynaVibe team member.
Vertical Accelerometer Placement
The purpose of the vertical accelerometer is to measure vertical hop and pitch axis vibration. This requires placing the vertical accelerometer in the forward cabin as pictured. If vertical hop is present at the 1-per, then its cause is blade asymmetry. If it is present twice per rotor rotation (at the 2-per), its cause is the advancing blade lift and drag. It’s usually possible to correct a 1-per vibration through tracking: making tracking better or worse depending on the blades. The 2-per vibration, however, is generally difficult to eliminate. For helicopters, DynaVibe engineers recommend using trim tabs to adjust the forward flight 1-per vibration.
For rotorcraft balancing, the full spectrum analysis capability the DynaVibe GX2 provides is excellent for troubleshooting. However, even the basic balancing capabilities of the DynaVibe Classic provide all that is necessary for rotor smoothing. The only frequencies requiring analysis are the prop, 1-per rotor, and 2-per rotor, which are within the scope of the DynaVibe Classic feature set. What also facilitates accurate rotorcraft balancing is expertise and knowledgeable customer service of the DynaVibe team.
Learn more by visiting the DynaVibe Rotorcraft FAQ.
DynaVibe is easy and economical to use for prop and rotorcraft balancing. For mechanics, shops and service centers, it adds profit to the bottom line. To learn about using DynaVibe to dynamically balance propellers and rotors, enter your email address below, visit the RPX Technologies website, or call: 405.896.0026.