Dynamic Prop Balancing

AdamZ

AdamZ

Touchdown! Greaser!
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Adam Zucker
Has anyone had experience with this outfit?
http://www.rpxtech.com/rpxweb/Dynavibe.asp

By way of brief background I fly with a group of pilots that fly a bunch of $100 omlette breakfast runs on Sunday. The group the Quakertown Pilots Assn ( QPA) will buy oil in bulk and bring in Avoincs shops to do transponder checks etc and get a discount as they can often get several plane owners to join in on what ever the are doing ie tranponder checks.

The group seemed interested in getting someone into do Dynamic Prop Balancing. The outfit that did it was going to charge around $265 as they were going to balance a bunch of props in one place on one day. By happenstance I ran across the Dynavibe in the above link. The Site seems very through and I though since the QPA had over 7 owners interested in the balancing that purchsing this unit and keeping it in the QPAs tool box for future use may be more cost effective. Any thoughts. AND I am I correct in assuming that once the weight was added or subtracted you would need an A&P sign off?

Interestingly the site give full instructions and doesn't seem to offer any great secret if only if you buy the product.
 
I don't think prop balancing is on the DIY preventative maintenance list, so it would have to be signed off. The old, "you get what you pay for" phrase applies here - I'd rather go to a shop that does this professionally that would do things like have calibrated test equipment, check the tracking of the blades, etc.
 
I had my A&P do that dynamic prop balance. They had a special a few years ago. Free prop balance or $100 off of an annual inspection.
 
AdamZ said:
Has anyone had experience with this outfit?
http://www.rpxtech.com/rpxweb/Dynavibe.asp

By way of brief background I fly with a group of pilots that fly a bunch of $100 omlette breakfast runs on Sunday. The group the Quakertown Pilots Assn ( QPA) will buy oil in bulk and bring in Avoincs shops to do transponder checks etc and get a discount as they can often get several plane owners to join in on what ever the are doing ie tranponder checks.

The group seemed interested in getting someone into do Dynamic Prop Balancing. The outfit that did it was going to charge around $265 as they were going to balance a bunch of props in one place on one day. By happenstance I ran across the Dynavibe in the above link. The Site seems very through and I though since the QPA had over 7 owners interested in the balancing that purchsing this unit and keeping it in the QPAs tool box for future use may be more cost effective. Any thoughts. AND I am I correct in assuming that once the weight was added or subtracted you would need an A&P sign off?

Interestingly the site give full instructions and doesn't seem to offer any great secret if only if you buy the product.
Click to expand...

I use to do prop balancing with an Aces 2020 ProBalancer, the same unit we used to track and balance rotor blades on a helicopter.

You must make a logbook entry or a Form 337 (depending upon engine manufacturer). The Lycoming can be balanced by placing bolts and washers on the starter flywheel, TCM engines you must drill the prop spinner backplate, thus a 337 is required.

Once the balance is done, then the spinner and prop are "indexed", marks are made on each so that if it's disassembled it can be reassembled and not screw up the balance.
 
Our EAA chapter just bought one of these units for member use only. We will use it as a fundraiser within the chapter. Several members are close to finishing their projects so it seemed the right time to get it. We will have a couple of designated "technicians" responsible its use and custody. For the members that have certified airframes we will have an AMT make the log entries.
 
Hey, I'd be interested in getting it done. Can I get a 2-for-1 special? ;)
 
It's worth doing. Don't know if they're the folks worth doing it with, sorry.
 
If you are really concerned about a good balance, take the prop off and have it statically balanced by a prop shop first. Then do a dynamic balance.

Prop manufacturers are not allowed to put weights in the shank of a blade. They must just select the best blades to put together. Sometimes the static balance of a new prop is not so great.

A prop shop, however, can put weights in the shank. This alone can be the real determining factor to a good overall balance.
 
Rotor&Wing said:
I use to do prop balancing with an Aces 2020 ProBalancer, the same unit we used to track and balance rotor blades on a helicopter.

You must make a logbook entry or a Form 337 (depending upon engine manufacturer). The Lycoming can be balanced by placing bolts and washers on the starter flywheel, TCM engines you must drill the prop spinner backplate, thus a 337 is required.

Once the balance is done, then the spinner and prop are "indexed", marks are made on each so that if it's disassembled it can be reassembled and not screw up the balance.
Click to expand...


the procedure to balance a prop is given in the manufacturers overhaul manual, The procedures there can only legally be completed by a CRS for props.

the only maintenance that can be completed in the field, is contained in the ICAs for the prop. and no balance procedure is given in the ICAs.

If you don't believe me, ask the manufacturer Sensenich and McCauley both have web pages ask there.

I sure ED at Sensenich will be glad to talk to you about what is legal to do in the field.
 
Tom-D said:
the procedure to balance a prop is given in the manufacturers overhaul manual, The procedures there can only legally be completed by a CRS for props.

the only maintenance that can be completed in the field, is contained in the ICAs for the prop. and no balance procedure is given in the ICAs.

If you don't believe me, ask the manufacturer Sensenich and McCauley both have web pages ask there.

I sure ED at Sensenich will be glad to talk to you about what is legal to do in the field.
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First of all you have to understand the difference between a propeller static balance and a dynamic balance. The CRS can do a static balance IAW manufacturers instructions. Any trained A&P can do a dynamic balance with the right equipment and data.

I had an FAA APPROVED manual for dynamic prop balancing with my Aces 2020 ProBalancer.

Dynamically "balancing" a prop involves placing balance weights on the flywheel of the engine or by placing weights on the spinner bulkhead. The only thing done with the prop is checking track or reindexing the prop on the crank, which any A&P can do.

If the weights were placed on the Lycoming flywheel then all is required is a logbook entry. If the backplate on the spinner was drilled and weights were placed there then a Form 337 was filed referencing the APPROVED data in the manual.
 
Rotor&Wing said:
First of all you have to understand the difference between a propeller static balance and a dynamic balance. The CRS can do a static balance IAW manufacturers instructions. Any trained A&P can do a dynamic balance with the right equipment and data.

I had an FAA APPROVED manual for dynamic prop balancing with my Aces 2020 Pro-Balancer.

Dynamically "balancing" a prop involves placing balance weights on the flywheel of the engine or by placing weights on the spinner bulkhead. The only thing done with the prop is checking track or re-indexing the prop on the crank, which any A&P can do.

Agreed

If the weights were placed on the Lycoming flywheel then all is required is a logbook entry. If the backing plate on the spinner was drilled and weights were placed there then a Form 337 was filed referencing the APPROVED data in the manual.
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Who makes the determination if that is a major or minor alteration? If your interpretation was correct any hole drilled in any portion of the aircraft will need a 337.
 
Tom-D said:
ACs are advice, nothing more. they are the methods that the FAA like to see, but are not binding like a FAR will be.,
Click to expand...

And their advice, on page 28, says:

(c) For aircraft or propeller manufacturers that provide procedures for dynamic balancing of the propeller in their maintenance manuals or instructions for continued airworthiness, propeller balancing is not considered a major airframe alteration.
(d) When approved aircraft or propeller manufacturer’s procedures are not available, there are other acceptable dynamic propeller balancing procedures. These include, but are not limited to the Chadwick-Helmuth Publication No. AW-9511-2, entitled “The Smooth Propeller”, and ACES Publication No. 100-OM-01, entitled “ACES Systems Guide to Propeller Balancing”. Dynamic balancing of propellers using FAA-approved or -accepted dynamic propeller balancing procedures is not considered a major propeller repair unless the propeller static balance weights are altered or when using the Chadwick-Helmuth or ACES type documents on propeller installations of 500 horsepower or more.

If there's a FAR that differs from this, they're guilty of offering bad or outdated advice.

Dan
 
Dan Thomas said:
And their advice, on page 28, says:

(c) For aircraft or propeller manufacturers that provide procedures for dynamic balancing of the propeller in their maintenance manuals or instructions for continued airworthiness, propeller balancing is not considered a major airframe alteration.
(d) When approved aircraft or propeller manufacturer’s procedures are not available, there are other acceptable dynamic propeller balancing procedures. These include, but are not limited to the Chadwick-Helmuth Publication No. AW-9511-2, entitled “The Smooth Propeller”, and ACES Publication No. 100-OM-01, entitled “ACES Systems Guide to Propeller Balancing”. Dynamic balancing of propellers using FAA-approved or -accepted dynamic propeller balancing procedures is not considered a major propeller repair unless the propeller static balance weights are altered or when using the Chadwick-Helmuth or ACES type documents on propeller installations of 500 horsepower or more.

If there's a FAR that differs from this, they're guilty of offering bad or outdated advice.

Dan
Click to expand...

Your information is right on. :thumbsup:
 
Dan Thomas said:
And their advice, on page 28, says:

(c) For aircraft or propeller manufacturers that provide procedures for dynamic balancing of the propeller in their maintenance manuals or instructions for continued airworthiness, propeller balancing is not considered a major airframe alteration.

That is correct so no 337 for a major alteration.

(d) When approved aircraft or propeller manufacturer’s procedures are not available, there are other acceptable dynamic propeller balancing procedures.

Name one propeller manufacturer that you will find in common use today that does not have manufacturer approved instructions for balancing. [/COLOR]

These include, but are not limited to the Chadwick-Helmuth Publication No. AW-9511-2, entitled “The Smooth Propeller”, and ACES Publication No. 100-OM-01, entitled “ACES Systems Guide to Propeller Balancing”. Dynamic balancing of propellers using FAA-approved or -accepted dynamic propeller balancing procedures is not considered a major propeller repair unless the propeller static balance weights are altered or when using the Chadwick-Helmuth or ACES type documents on propeller installations of 500 horsepower or more.

If there's a FAR that differs from this, they're guilty of offering bad or outdated advice.

Dan
Click to expand...

Did you see the OP's little hand held device on that list, do you believe the instructions that come with the device has FAA approval?
 
The next question, show me one set of ICA's for any prop that says this prop can be dynamically balanced in the field.

Remember the ICA's are what is allowed to be completed by A&P's in the field, any other routine that comes from the overhaul manual is a major repair to be completed by an authorized prop repair station, with the equipment required by the manual.

If I'm wrong, show me a set of ICAs that allow A&Ps to do balancing in the field.
 
Hartzell's "Propeller Owner's Manual and Logbook," Manual #115N, is FAA Approved and gives detailed information about dynamic balancing in the maintenance section. Here are some quotes from the manual...
"The purpose of this manual is to enable qualified personnel to install, operate, and maintain a Hartzell Constant Speed orConstant Speed Feathering Propeller."


"Dynamic balance is recommended to reduce vibrations that may be caused by a rotating system (propeller and engine) imbalance. Dynamic balancing can help prolong the life of the propeller, engine, airframe, and avionics."​


"Follow the dynamic balance equipment manufacturer’s instructions for dynamic balance in addition to the specifications of this section."​


​
 
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