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Hartzell Blended Airfoil Blade 7496 vs New 7497 Performance & Limitations

gmcjetpilot

Well Known Member
The BA prop came out about 2003 and has restrictions of RPM and/or MP, as noted in Vans Information and notices March 2003. This was blade 7496.

The new BA blade is 7497. This newer design was a rumored to not have RPM limits. I called Hartzell and they said this is not correct. They have not tested so there are no limits published.

As far as performance Hartzell says the new BA blade 7497 is as good or better than the original BA bladed 7496.... Others say there is a hit on performance.

Discussion....
 
I have only flown my RV7A with a 7497 prop. Likely for a number of reasons, my 7 doesn’t quite get to Vans cruise numbers. The prop may be the major contributor to this. It will be interesting to hear if anyone has had the opportunity to fly both props on the same engine/airframe.

Further, it surprises me to hear Hartzell says there’s no rpm restrictions because they haven’t tested it. Isn’t this a certified prop?

Bevan
 
The BA prop came out about 2003 and has restrictions of RPM and/or MP, as noted in Vans Information and notices March 2003. This was blade 7496.

The new BA blade is 7497. This newer design was a rumored to not have RPM limits. I called Hartzell and they said this is not correct. They have not tested so there are no limits published.

As far as performance Hartzell says the new BA blade 7497 is as good or better than the original BA bladed 7496.... Others say there is a hit on performance.

Discussion....

George, on 12th September 2007 you posted on VAF that you had contacted Hartzell regarding the F7496 and F7497 and the following were your verbatim comments:

"I sent a note to Hartzell asking why the change and if there are any restrictions. I will post their reply when I get it.I had a long talk with hartzell.

The 7496 was their first go at it. Its a fine blade and a little thinner than the 7497. As they developed the 7497 for the IO360 angle valve they realized it would work on the 180HP as well with out the small limitations.

I asked about weight and loss of performance?

Yes the 7497 weighs a little more but as a percentage of the props total weight its very small (no specifics given).

Performance? Talking to the engineer that did the flight test development for the 7497 there may be a slight hit on speed, but its too small to measure. Hartzell has the same challenges in getting good flight test data like we all do, especially when trying to compare two different props.

If you have the 7496 blade it still rocks and you do get that slight weight advantage and minor edge on speed. The limits on the 7496 are pretty minor. So if you have a 180HP 360 you have the choice of either. However if buying new today, the 7497 with no limits is the way to go as Hartzell recommends."


You thus reported that there were no limitations on the F7497 on a 180 HP engine, that the F7497 was slightly heavier, and that the F7496 has a minor edge in speed. I took the liberty of highlighting some of your comments in red.I think you were largely correct in 2007.
 
George, on 12th September 2007 you posted on VAF that you had contacted Hartzell regarding the F7496 and F7497 and the following were your verbatim comments:

"I sent a note to Hartzell asking why the change and if there are any restrictions. I will post their reply when I get it.I had a long talk with hartzell.

The 7496 was their first go at it. Its a fine blade and a little thinner than the 7497. As they developed the 7497 for the IO360 angle valve they realized it would work on the 180HP as well with out the small limitations.

I asked about weight and loss of performance?

Yes the 7497 weighs a little more but as a percentage of the props total weight its very small (no specifics given).

Performance? Talking to the engineer that did the flight test development for the 7497 there may be a slight hit on speed, but its too small to measure. Hartzell has the same challenges in getting good flight test data like we all do, especially when trying to compare two different props.

If you have the 7496 blade it still rocks and you do get that slight weight advantage and minor edge on speed. The limits on the 7496 are pretty minor. So if you have a 180HP 360 you have the choice of either. However if buying new today, the 7497 with no limits is the way to go as Hartzell recommends."


You thus reported that there were no limitations on the F7497 on a 180 HP engine, that the F7497 was slightly heavier, and that the F7496 has a minor edge in speed. I took the liberty of highlighting some of your comments in red.I think you were largely correct in 2007.

Thanks for the correction and clarification. This is what Hartzell sent me:

New Hartzell "Blended Airfoil" HC-(C,F,M)2YR-1(B)FP/F7497 Prop Recommended For Lycoming O-360-A1(A, C, D, F, G, H, P) and Superior O-360-B( )( )2 Engines

Flight testing of a new "blended airfoil" Hartzell propeller has been accomplished in accordance to FAR 23.907 to ensure compatibility with the Lycoming O-360-A1(A, C, D, F, G, H, P). As a result of this testing, Hartzell propeller model HC-(C,F,M)2YR-1(B)FP/F7497 is recommended for use with these engines. The following results were obtained:

Hartzell Propeller Model HC-(C,F,M)2YR-1(B)FP/F7497 is vibrationally approved when mounted on Lycoming Model O-360-A1(A, C, D, F, G, H, P) engines rated at 180 HP at 2700 RPM without dampers (8.5:1 compression ratio) with magneto ignition and installed in normal category type single engine tractor aircraft such as the Van's RV series. There are no operating restrictions.

Diameter range is 74" to 72".

At this time no aerobatic testing has been performed with the above listed propeller and engine combinations.

Testing of this propeller on the Lycoming Model O-360-A1( ) engine equipped with Electronic Ignition and/or FADEC has not been conducted at this time.

Hartzell Propeller Model HC-(C,F,M)2YR-1(B)FP/F7497 is vibrationally approved when mounted on Superior Model O-360-B( )( )2 engines rated at 180 HP at 2700 RPM without dampers (8.5:1 compression ratio) with magneto or electronic ignition and installed in normal category type single engine tractor aircraft such as the Van's RV series. There are no operating restrictions.

Diameter range is 74" to 72".

At this time no aerobatic testing has been performed with the above listed propeller and engine combinations.

Testing of this propeller on the Superior Model O-360-B( )( )2 engine equipped with FADEC has not been conducted and is not a recommended combination.

NOTE: Propeller vibration characteristics and stress amplitudes on a reciprocating engine installation are primarily mechanically generated by the engine. Any modification to the standard engine configuration to include high-compression pistons, electronic ignition, FADEC, tuned induction and exhaust, and turbo-charging or turbo-normalizing have the potential to adversely affect the propeller vibration characteristics and stress amplitudes. Hartzell Propeller therefore does not endorse any such engine modification unless the specific engine and propeller configurations have been tested and found to be vibrationally acceptable according to 14 CFR 23.907.


So bottom line read it as you will. I have a genuine Lycoming O-360-A1A and they only tested the new BA 7496 prop with magneto's. If you have a Superior O-360-B() Hartzell tested that engine with the new blended airfoil prop with both EI and Mags. Are you safe to fly a Genuine Lyc O-360 180HP with EI and assume no limitations? Up to you.

They don't say what kind of EI. Any changes you make to the engine effects the prop vibration characteristics. Hartzell can't test every experimental configuration. If you have 4 into 1 exhaust, fancy induction, Hi Comp pistons, EI not tested, it all changes.

Give credit to Hartzell, Sensenich and Whirlwind, who are smart enough to support the experimental market. Hartzell's testing improves safety and understanding. If vibrations are a worry (and they are not for me), you can go the wood/composite prop route, which have natural dampening, but they cost a lot more, for only a little weight savings and no performance gain (subject to lots of debate I am sure).
 
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Yes, the prop is certified.
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But note the restrictions listed in the first paragraph on Page 9:

"The maximum and minimum propeller diameters that can be used from a vibration standpoint are shown below. No reduction below the minimum diameter listed is permissible, since this figure includes the diameter reduction allowable for repair purposes.

The engine models listed below are the configurations on the engine type certificate unless specifically stated otherwise. Modifications to the engine or airframe that alter the power of the engine models listed below during any phase of operation have the potential to increase propeller stresses and are not approved by this list. Such modifications include, but are not limited to, the addition of a turbocharger or turbonormalizer, increased boost pressure, increased compression ratio, increased RPM, altered ignition timing, electronic ignition, full authority digital engine controls (FADEC), or tuned induction or exhaust. Also, any change to the mass or stiffness of the crankshaft/counterweight assembly is not approved by this list."​
Good Info. Hartzell has STC's to replace the older F7666 prop blade with the F7497 (Mooney, Piper...). This is for stock certified 180 and 200 HP engines with magnetos. 200HP IO-360's have counter weight/dampened crankshaft which helps prop. The Electronic ignition which is common now was newish in 2003. It seems EI makes a difference in how the metal Prop vibrates, especially on the 180HP engines (with out crank dampers). This was a revelation 15 years ago. Now we know. Good to have some data.

I have my engine but no prop yet. My plan is with my O-360 A1A Lyc dual EI, I'll observe the 2000-2250 limit and 2600 RPM (except TO) limit regardless of what Hartzell I put on it.
 
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