Hatzell BA prop should be OK, w/ caveat
rickmellor said:
I've been bouncing back and forth on which engine to put in my 7A and have a strong interest in ECI's 340 stroker. Can anyone who's running this engine post which propeller you're using and your impressions of it?
I've got two choice props in mind that seem like they'll work:
1) Hartzell BA (C2YR-1BF/F7496-2), 72", 180HP
2) Whirlwind 200 RV
The Hartzell is my preferred prop but I'm pretty certain that if I ask them if it'll work with this engine they'll say no because they haven't tested it. If I ask the Whirlwind guys (they don't seem to answer emails) they'll probably say "no problem".
What to do, what to do... -Rick
I would not assume they say no, in fact the 320 is easier than the 360 on props. It's possible they may give you positive indication that its OK. However you are right they don't KNOW 100% for sure unless they test it. If there is enough IO340's they will test them, may be on your plane if you volunteer.
I think a possible show stopper or at least detail could be the crank pattern or bushing size? The 320 takes a C2Y
L hub? The C2Y
K and C2Y
R hub goes on the 360.
K hubs - have six, 1/2" bolts on 4-3/4" circle and four 3/4" drive bushings
R hubs - same as K but has five 3/4" drive bushings
L hubs - similar to K hub but uses 7/16" bolts and 5/8" drive bushings
So you may(?) need to change the bushings may be not? I don't know what kind of crank flange they install on the IO340X, but I assume it will be more in line with the 320's "L" hub, but if you had a choice, you may want them to install the 360 "R" bushings. Of course the (I)O320 prop Van sells is the C2YL-1BF/F7663-4, I am sure that would fit.
Call or email the IO340 manufacture and Hartzell, ask them what they think.
I would could see being comfortable with a BA prop for the 360 on a 340. As you probably know 320's tend to have NO rpm or restrictions of any kind with hartzell's. Why? Well the 360 (with out dampened crank) is a bit of a brute in the power pulse department. I don't know much about the 340 but its 170HP and the extra 10HP is from longer stroke, I think. That should not be any more hostile vibration wise than a 360 with Hi Comp pistons or electronic ignition, my guess. The BA prop is approved for 360's with EI with some small point limitations.
The TRUTH is anything other than what's tested is a guess. Right now Hartzell has tested the HC-C2YK/F7666-2 -4 and C2YR-1BF/F7496-2 or -4, on 360's with electronic ignition and FADEC, on RV's. The airframe is included because airframe can have something to do with prop vibrations, so it's best to test the whole combination.
The worse possible case, 360, un-dampened crank, electronic ignition and/or hi-comp pistons with the older Hartzell C2YK/F7666. The BA is better than the older C2YK/F7666, even with EI. It has no "range" of stay out RPM or life limit, just a point power settings to avoid which does not affect normal operations.
The unknown of the 340? You really need to call or write them. I can assure you Hartzell will get back to you. Hartzell can't approve or disapprove the 340 unless they have tested it. I find they don't get real excited about much, like Oh My Gosh! Its a little more subtle, and has to do with fatigue life. They want infinite fatigue life and very large margins. My feel is they will not get too excited and tell you to be cautious. If you use a combo of C2YK/F7666 and the C2YL/F7496 restrictions, it will have minor or nil affect on you operationally. IT's probably not necessary but it's something to consider.
My advice is use the most conservative restrictions or combination of the most conservative restrictions until a 340/Hartzell test is done, which no doubt will be done at some point down the road, especially if the engine becomes popular. The BA prop has now been tested on the IO390 angle valve. It took time because they work on the more popular engines first. I asked Hartzell how much it would cost to do a vibration test on an individuals plane? $25,000 to $50,000. I bet if the 340 is popular they will test it at some point on their nickle.
I'v talked to Hartzell's engineering a few time about this general topic, engine mods and prop limitations. For example Hi comp pistons. All you high compression piston operators with Hartzell's are in the same boat as the 340, there is no test data. They have NOT tested hi comp pistons, but its assumed it has similar effect as electronic ignition.
May be the 340 engine manufacture will work with Hartzell and pay for it? It all depends on how many they sell.
As far as the other brands? Who knows what test they are doing. Wood cores tend not to be critical; "God's Composite", aka wood tends not to be fatigue critical and dampens vibes well. However again, if not tested ON THE AIRFRAME with your exact engine config, piston, ignition and so on, than its an unknown. Whirl Wind? I don't know. I got the feeling they did not do vibration surveys. I could be wrong. They used McCauley hubs (and think still do) with their blades. Not sure if they are wood core? Again composites are pretty good in fatigue and vibrations, but there's NO guarantees unless a vibration survey is done.
Hartzell can't test every little engine mod experimental guys and gals throw out there. IF you have a stock 320 or 360, you're covered. A 320 or 360 with EI or FADEC, they have data and are covered. However these new 340's and high compression pistons, you kind are in a fuzzy area.
Overall you Hartzell has very high standards and safety margins. There goal or going in postion is
infinite fatigue life. Unlike helicopters most GA planes rarely have "Life Limited Parts". I suspect the 8,700 hour limit on the C2YK/F7666 on 360's, with EI, is conservative. Besides flying 150 hours a year, 8,700 hours is 58 years. Also most metal blades eroded at some point from sand, gravel on takeoff and rain in flight. Still the LIMITATIONS do not severely affect the utility.
If you get a BA prop, it should last a life time and be very safe. The only other down side is it may not be perfectly optimal, since its made for a +180 HP engine, but it should be better than the prop made for the 320. That would be a good question to ask Hartzell.
If you go with a boutique small company like whirlwind or aerocomposites, there is no guarantee you will not have problems. Even if they eventually return your calls and say "no problem". (Note: if you can't get a returned call, what do you thing repair and service is like?)
Hartzell just happens to KNOW the limitations. Just because there are no limitations published on the other brand props, which have not been in service very long, does not mean there's no gotchas out there. I would go Hartzell my self, less expensive, better performance and better support.