Your prop was statically balanced at the factory and that's good enough?
A static balance may balance the prop but it does not correct the net imbalance of the rotating assembly.
This is a relatively new, statically balanced prop on a Cessna 210. The first "statically balanced" reading was 0.6 IPS, which is pretty typical. It took 10 large washers (mind the reflection which makes it look like 20) on the spinner to pull it into balance (0.06 IPS).
This may look like a lot of weight, but the rotational forces are now neutral! Before the prop was dynamically balanced, this is the amount of weight was constantly shaking the airplane and stressing every part of the engine and airframe. That's a LOT of stress at 2000+ RPM!!!
The point is that a prop static balance is not enough. The static balance gets the balance in the ball park but you really need to balance the entire assembly. Not just the prop. The latest data that we have been analyzing shows that around 80% of all GA aircraft are flying with imbalanced props even though most were statically balanced.
Running your air cooled engine with the cowl removed is harder on the engine than you may realize. Uncowled, air is blown over the cylinders and not through the cylinder's cooling fins. So the bottom of the engine is left to heat-soak and the top is cooled. This uneven heating results in distorted cylinders which damages the cylinders and the moving parts inside the cylinders.
Continental recommends fabricating a scoop out of sheet metal for use when running up the engine on the ground when the cowl is removed. This provides a safe amount of airflow for runups and can usually be constructed in a way that it is out of the way for most maintenance procedures. (Drawing credit: Continental Motors)
I've found a live round in an "unloaded" gun and I've found a hot mag before grabbing a prop! Both are sobering, possibly deadly, experiences and they both happen more than you think.
During shutdown, the procedure drilled into my head when learning to fly was "Mixture, Master, Mags." I can still hear my flight instructor's voice today. And before hooking a tow bar to a plane, I ALWAYS verify "Key out?" NOT "Mags off?" Here's why.
"Mixture, Master, Mags," deplane, grab the tow bar, reach for the prop to turn it so it clears the tow bar. Are the mags off? Are you sure? Of course! You remember turning the key just a second ago. All safe.
Ok, Look at the key. That's not off! That's why the procedure is "Key Out!" and preferably on top of the panel where you can see it.
Royal Lee Organics is a subsidiary of Standard Process®. Since 1929, Standard Process has been dedicated to the field of nutritional supplements and the whole food philosophy introduced by Dr. Royal Lee. Royal Lee Organics provides organic ingredients as well as a re-designed version of Dr. Lee’s household flour mill that was originally designed in 1949.
When Dr. Lee first developed the mill in the 1940’s, he was concerned about what was happening to flour. In order to avoid spoilage, commercial mills were discarding the germ and the bran through a process called extraction, resulting in a less nutritious ingredient. Dr. Lee provided an alternative, allowing bakers to purchase and store grains in their natural state and mill them at home when needed. The result was fresh flour with all of its naturally occurring nutrients.
The original Lee flour mills were manufactured by hand, and many of them from the past 50 years are still in use which is a testament to the reliability and durability of the design. The previous manufacturing process, however, was expensive and time-consuming, so the engineering team made some changes to the flour mill in order manufacture it in a production environment.
One of the challenges the engineering team dealt with involved the rotating disk inside the mill. This disk creates an air current that rubs the grains up against the stone, an action that reduces the grains into flour. This disk rotates at high speeds, between 5,000 and 10,000 RPM. Anytime a component that rotates at such high speeds is out-of-balance, it will create problems. The least of these problems is that the machine becomes louder, which is unpleasant for the user. A more damaging consequence is that vibrations from out-of-balance conditions can cause early life failure of the motor. For these reasons, the Lee engineering team spent a lot of time determining what to do about balancing these rotating disks.
The team considered sending the disks to a third party for professional balancing, but that option proved too expensive and impractical. Instead, the team developed a manufacturing process that produces disks that are true and round. This resulted in a component that is as “in-balance” as possible. To verify this, the Lee Engineering team built a testing procedure using the DynaVibe GX2 system to measure vibration of the motor and rotating disk. Now, the vibration level of every flour mill is tested before it leaves the factory, ensuring that they fall within the specification limits the engineering team developed through various trials.
DynaVibe is helping assure that consumers are getting flour mills that live up to the traditions of quality and reliability for which the brand is known. The full vibration spectrum and balance data that DynaVibe provides also gives the Lee Engineering team baseline metrics and set of benchmarks the team can use to further improve the design of the mill in the future. With DynaVibe, there is certainty about how much vibration may exist and where it comes from. This helps ensure that the flour mills that leave the factory meet the standard of excellence.
To learn how DynaVibe can address your equipment balancing or vibration analysis needs, simply enter your email address in the box below. Shop for a DynaVibe system in the online store, or contact us with your questions at 405.896.0026 or firstname.lastname@example.org.
In the space of a few years, Unmanned Aerial Vehicles (UAVs) or drones have gone from being in the domain of the military or hobbyists to mainstream. An article in Business Insider shares data from a PwC report predicting that drones could replace billions of dollars of human labor, as the chart from this article shows:
As the chart illustrates, drones are projected to have the biggest commercial impact in the infrastructure and agriculture sectors. For example, human inspections of wind turbines are costly and potentially dangerous. SkySpecs, a startup company deploys drones to conduct safe, automated inspections at about half the cost of human inspections.
The RPX Technologies team recently participated in the Association for Unmanned Vehicle Systems International (AUVSI) Xponential exhibition, where the interest in dynamic balancing and vibration analysis for drones was high. It’s easy to understand the reason why: The commercial use of UAVs almost always involves high quality, high-resolution video or photography, and vibration impairs this application. Furthermore, sustained vibration can lead to failure of airframes, instruments and engines in just the same way it does in sport, general and commercial aviation aircraft. Commercial drone operators are discovering that DynaVibe helps ensure they are delivering the highest quality services to their clients, while also keeping their fleets at maximum readiness.
DynaVibe is a dynamic propeller balancing and vibration analyzing system. Simple to use, it allows UAV owners and operators to quickly measure and resolve propeller vibration. While vibration dampening mounts and gimbals can help minimize the effects of vibration, the best approach is to eliminate it altogether. Eliminating vibration is of particular importance with UAVs, because these lighter structure aircraft are more prone to shake from vibration than are larger, heavier aircraft.
The DynaVibe GX2 also allows users to conduct full-spectrum vibration surveys to identify and resolve vibration from sources other than the propeller. The benefit of dynamically balancing and analyzing the vibration of drones is the smoothest, quietest flight to enable maximum resolution of photography, and highest possible uptime of all flight systems. To learn more about the benefits of DynaVibe for UAV operations, contact us by phone at 405.896.0026 or by email: email@example.com. Shop in our online store for DynaVibe. Or, simply provide your email address in the form below and we’ll contact you.
Unmanned Aerial Vehicles (UAVs), or drones as they are commonly known, are subject to the same vibration issues as other propeller-driven aircraft. An unbalanced prop assembly can create vibrations that damage the engine, airframe instruments and interfere with the mission.
Excessive vibration can interfere with the mission of a UAV, particularly those used for surveillance, reconnaissance, and aerial filming or photography. Vibration can distort the image. Vibration dampening camera mounts and gimbals are commonly used in UAVs to deal with this problem, but the ideal solution is to eliminate the source of the vibration. Balancing the propeller assembly with DynaVibe easily does this, and the DynaVibe Classic provides an affordable solution for UAV operators who need to the highest possible image quality.
For more information about the benefits of dynamically balancing UAV propeller assemblies, contact the DynaVibe team by phone at 405.896.0026 or by email: firstname.lastname@example.org. Visit our online store to shop for DynaVibe, or simply provide your email address in the form below and we’ll contact you.
Bob Pastusek is vice-president and a board member of the Lancair Owners & Builders Organization – LOBO – and is their go-to maintenance guy. A few years ago, the LOBO Board became concerned that people were not tuning up their airplanes properly; they were not following all the recommended engine and airplane manufacturer’s guidelines in doing their condition inspections. “Experimental owners are not obliged to follow them,” said Pastusek. “Nonetheless, like putting air in your tires or oil in your engine, some recommendations are more significant than others. We came to the conclusion that some people were not doing some of the important ones, based on accidents and probable cause findings that indicated maintenance wasn’t as good on these airplanes as it could be.”
In December 2014, LOBO put together a kit of materials for testing and inspecting the engines, specifically Continental aircraft engines. “This worked out really well for us,” Pastusek continued. “So at the fall LOBO fly-in, we asked what people (members) thought about it, and the feedback expressed a desire to include some additional equipment in the kit. One of the principal requested pieces of equipment was a prop balancer.”
Pastusek first learned about the DynaVibe propeller balancing system at Oshkosh four or five years ago. He bought one for his local EAA chapter and has used it several times to help chapter members balance their props. “Having personal experience with DynaVibe, knowing that it works and that it is a reasonably priced piece of gear that our average homebuilder could figure out how to use, we bought new DynaVibe systems to include in our three engine inspection and tune-up kits.”
Pastusek recognizes the importance of keeping the prop in balance. “It makes the airplane engine run smoother, with less wear-and-tear on the engine. The aircraft is much more pleasant to fly.” In general, Lancairs use factory-balanced, high-end adjustable pitch props. “They come pretty well balanced; we generally don’t have an issue with props significantly out-of-balance. However, there are a couple of things that homebuilders can do, particularly in mounting the spinners and things like that, that can cause them to be out of balance. It’s a very easy thing to check and improve. If you find the prop out of balance and fix it, it really makes the airplane run a lot smoother. These are very large engines in relatively small and lightweight aircraft, so a prop imbalance will shake the airplane around pretty well.”
The LOBO engine test kit with the DynaVibe prop balancing system is expected to be available to members in April 2016. “We think the DynaVibe is a relatively sophisticated but easy tool to use in the field,” Pastusek concluded. “It works like a champ.”
The affordable DynaVibe Classic propeller balancing system is just $1,495 shop for it the DynaVibe online store. If you'd like to know more about DynaVibe, please contact us at 405.896.0026, email@example.com, or simply enter your email address in the form below and we'll contact you!
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 405.896.0026, send email to firstname.lastname@example.org or enter your email address in the form below.
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 405.896.0026 or by email: email@example.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.
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 405.896.0026, send email to firstname.lastname@example.org 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.