Metal Props and Electronic Ignition

[FasGlas]

It really has to do with what prop on what engine. Some props have restrictions and some don't. The Hartzell BA prop does not have any restrictions whereas Hartzell props with F7666 & F7068 blades do. As for increased harmonics, adding additional forces increases the restriction problem, such as 10:1 pistons, more that stock advance, etc. I just had a conversation with Hartzell about this very subject and I changed props. A harmonic will actually split a blade in half during flight.

[RVDan]

From Hartzell Service letter HC-SL-61-61Y.

?The engine models listed are the configurations tested. Modification to the engine that alters the power of the engine models listed in Table 2 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 turbo charger 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.?

The same statement is in the prop manual 115N for the compact hub propellers.

There is also a statement from Hartzell somewhere saying that they tested certain prop and engines with electronic ignition.

[koupster]

This from Hartzell Manual 115N:
AIRWORTHINESS LIMITATIONS
Propeller: HC-C2YR-1BF/F7666A-2Engine: Lycoming O-360-A1A rated at 180hp at 2700 RPM equipped with Lightspeed Plasma II electronic ignition Max. Diameter 74 inches Min. Diameter 72 inches
Operating Restriction: ?Avoid continuous operation between 2000 and 2250 RPM. Operation above 2600 RPM is limited to takeoff. As soon as practical after takoff, the RPM should be reduced to 2600 RPM or less.?

This from http://hartzellprop.com/pilots/kit-b...w-prop-design/ (Listed under Glasair)
LYCOMING (I)O-360-B1A RESTRICTIONS:
Hartzell Propeller Model HC-C2YR-1BF/F7496 is satisfactory vibrationwise mounted on Lycoming model O-360 A1A rated at 180HP at 2700 RPM and equipped with magneto ignition and/or Lightspeed Plasma II or LASAR electronic ignition installed in similar single engine tractor aircraft with the following operating restrictions.
1) Do not operate above 22″ manifold pressure below 2350 RPM.
2) Operation above 2600 RPM is limited to takeoff. As soon as practical after takeoff the RPM should be reduced to 2600 RPM or less.
The propeller diameter limits are 74 to 72 inches.

Cheers, David
KBTF - RV-6A

[Vansconvert]

Originally Posted by koupster

This from Hartzell Manual 115N:
AIRWORTHINESS LIMITATIONS
Propeller: HC-C2YR-1BF/F7666A-2Engine: Lycoming O-360-A1A rated at 180hp at 2700 RPM equipped with Lightspeed Plasma II electronic ignition Max. Diameter 74 inches Min. Diameter 72 inches
Operating Restriction: ?Avoid continuous operation between 2000 and 2250 RPM. Operation above 2600 RPM is limited to takeoff. As soon as practical after takoff, the RPM should be reduced to 2600 RPM or less.?

This from http://hartzellprop.com/pilots/kit-b...w-prop-design/ (Listed under Glasair)
LYCOMING (I)O-360-B1A RESTRICTIONS:
Hartzell Propeller Model HC-C2YR-1BF/F7496 is satisfactory vibrationwise mounted on Lycoming model O-360 A1A rated at 180HP at 2700 RPM and equipped with magneto ignition and/or Lightspeed Plasma II or LASAR electronic ignition installed in similar single engine tractor aircraft with the following operating restrictions.
1) Do not operate above 22″ manifold pressure below 2350 RPM.
2) Operation above 2600 RPM is limited to takeoff. As soon as practical after takeoff the RPM should be reduced to 2600 RPM or less.
The propeller diameter limits are 74 to 72 inches.

Cheers, David
KBTF - RV-6A

That is the info I was referring to.

[DanH]

Originally Posted by Full Throttle

That's what Superior thought when they retarded the spark on the XP-400 angle valve engine from 25 to 20 degrees before top dead center. Didn't work and they still broke cranks.

I'm not sure what Superior thoughts you refer to, but 20 and 25 are base timing figures with little bearing on the subject under discussion.

[Full Throttle]

As you were saying "That in itself is ironic, given angle valve engines generally incorporate pendulum absorbers." Since you were relating to crankshafts with pendulum absorbers. My comment was only an association. That's what the XP-400 had.

[DanH]

Originally Posted by Full Throttle

As you were saying "That in itself is ironic, given angle valve engines generally incorporate pendulum absorbers." Since you were relating to crankshafts with pendulum absorbers. My comment was only an association. That's what the XP-400 had.

Ahh. I'll go back and delete that note, so as to not further confuse the issue under discussion...propeller blade stress increase due to increasing ignition advance.

[rvbuilder2002]

Originally Posted by koupster

This from Hartzell Manual 115N:
AIRWORTHINESS LIMITATIONS
Propeller: HC-C2YR-1BF/F7666A-2Engine: Lycoming O-360-A1A rated at 180hp at 2700 RPM equipped with Lightspeed Plasma II electronic ignition Max. Diameter 74 inches Min. Diameter 72 inches
Operating Restriction: ?Avoid continuous operation between 2000 and 2250 RPM. Operation above 2600 RPM is limited to takeoff. As soon as practical after takoff, the RPM should be reduced to 2600 RPM or less.?

This from http://hartzellprop.com/pilots/kit-b...w-prop-design/ (Listed under Glasair)
LYCOMING (I)O-360-B1A RESTRICTIONS:
Hartzell Propeller Model HC-C2YR-1BF/F7496 is satisfactory vibrationwise mounted on Lycoming model O-360 A1A rated at 180HP at 2700 RPM and equipped with magneto ignition and/or Lightspeed Plasma II or LASAR electronic ignition installed in similar single engine tractor aircraft with the following operating restrictions.
1) Do not operate above 22″ manifold pressure below 2350 RPM.
2) Operation above 2600 RPM is limited to takeoff. As soon as practical after takeoff the RPM should be reduced to 2600 RPM or less.
The propeller diameter limits are 74 to 72 inches.

Cheers, David
KBTF - RV-6A

Keep in mind that the above approval is for a very specific engine and ignition configuration.
This came as a result of extensive testing done during a collaboration between Harzell test engineering and Vans Aircraft in the early 2000's.
At the time, the test results surprised the Hartzell engineers and it resulted in a whole new perspective regarding their involvement in supplying propellers for the experimental market.

I think the best point to be taken from their published data is that what may seem to be a very minor modification, could induce just enough change that it would push a particular engine/prop. combination outside of the originally safe operating envelope.
The bottom line is that if you can't find a specif approval for the exact configuration you are running or considering to run, you are operating in a realm of the unknown.

[DanH]

The FAA publishes a good AC on propeller vibration certification:

https://www.faa.gov/regulations_poli...mentID/1018497

In addition, Marc Cook wrote a fine article detailing the test process when Hartzell certified the BA/IO-390 combination, using his own airplane as the test mule. You can find the article and download it at Kitplanes.com.

[akschu]

Originally Posted by DanH

And technically, "electronic ignition" has nothing to do with it.

The issue is advanced timing, not the method of generating a spark. A magneto set for advanced timing would net the same result.

It's important to remember, for two reasons. First, there are now multiple EI's available which enable fixed timing or limited advance. Second, an increasing body of evidence says the angle valve engines don't respond to highly increased advance like the parallel valve engines.

I recall reading that the bigger factor between EI and mags (beyond the obvious timing changes) was how they are triggered. In the case of crank position trigger, the spark timing is more accurate and can contribute to vibration, while mags triggered off of the backside of the case tended to drift around ever so slightly.

After reading that, I messaged Hartzell with:

I purchased this prop years ago for my bearhawk. I have a io-540-c4b5 250hp engine and plan on running the gov up to 2700 to get the extra 10hp because the internals are the same as the 260hp model.

As far as I know this all works together, but I also want to run electronic ignition and wanted to know if there are any known problems with this engine, prop, and EI combination.

They responded with:

Hello Matt,

Thank you for contacting Hartzell Propeller.

Our engineering group states that the propeller can be used up to 2700 RPM without operating restrictions. The propeller diameter is limited between 84 and 76 inches.

We do not have any data on electronic ignition with this propeller/engine combination. Use of electronic ignition is not necessarily prohibited, but it would be at your risk.

If you have any additional questions, or if we can be of further assistance, please do not hesitate to contact us.

At this point I'm not sure what I'm going to run. I like the simplicity of the surefly, but I also like the tunability of the CPI-2, especially if I run any amount of mogas.

schu