Prop for RV7..Need a new one?

[extralite]

HI all.

I sent my Hartzell adjustable pitch prop up the prop shop for an inspection. (10yr). They say the blades are out of spec near the tips and i need new blades. $7k plus GST each. The performance has been great, i cant see a safety issue as the RPM is always within limits, so it seems a bit excessive to spend close to $16k on new blades. . It is experimental category but not built by myself. It actually works out more economical to just get a new one ($25k plus GST).

Are there any options here? First i suppose if anyone has a contact for some blades that may be within spec. Secondly, is it actually a requirement? A small margin out of spec is not a safety or performance issue for me, so just wondering if there is any choice in this.

thanks for any suggestions.

[djpil]

A short story to explain one reason why the diameter limits exist: Propeller Vibration: Issues, Examples, Consequences, by EPI Inc. (http://www.epi-eng.com/propeller_technology/propeller_vibration_issues.htm)
It specifically mentions your situation.

Note it states: "to be sure that a particular prop will survive the fatigue environment produced by a particular engine on a particular airframe". As yours is Experimental the question is what limits the prop shop is using? Did someone make up limits for your manual or are they using TCDS data or just assuming it is like a similar certified airplane?

The Type Certificate Data Sheet for my prop states blade diameters from 68 - 74 inches but the AFM for my airplane has limits of 72 - 74 inches. Performance may be a factor there as it is a certified airplane, I don't know that detail.

[machtuk]

HI all.

I sent my Hartzell adjustable pitch prop up the prop shop for an inspection. (10yr). They say the blades are out of spec near the tips and i need new blades. $7k plus GST each. The performance has been great, i cant see a safety issue as the RPM is always within limits, so it seems a bit excessive to spend close to $16k on new blades. . It is experimental category but not built by myself. It actually works out more economical to just get a new one ($25k plus GST).

Are there any options here? First i suppose if anyone has a contact for some blades that may be within spec. Secondly, is it actually a requirement? A small margin out of spec is not a safety or performance issue for me, so just wondering if there is any choice in this.

thanks for any suggestions.

being experimental there was no need for a 10 yr inspection on yr prop! AD/PROP/1 Amdt 2

[Squawk7700]

It’s your life (and your passenger) behind the prop!

Have you seen how much a prop bends when in use? Demonstrated by the q-tip effect when you have a prop strike.

[poteroo]

Why do you need a CS prop on an RV7 anyway? A fixed pitch Sensenich, tweaked out to 87 inches will be just as fast, and a heap cheaper and less costly to maintain. You seriously don't need a CS prop on an RV because their takeoff performance is great with FP.

I've flown every make & model of RV except the 12, and just can't see any justification in CS props. Save your money and revamp your avionics instead.

PM me if you like.

happy days,

[machtuk]

Why do you need a CS prop on an RV7 anyway? A fixed pitch Sensenich, tweaked out to 87 inches will be just as fast, and a heap cheaper and less costly to maintain. You seriously don't need a CS prop on an RV because their takeoff performance is great with FP.

I've flown every make & model of RV except the 12, and just can't see any justification in CS props. Save your money and revamp your avionics instead.

PM me if you like.

happy days,

My Vans has a CS prop I've flown FP, chalk and cheese! No contest! -)

[Squawk7700]

Two mates of mine did simultaneous RV6 builds. One with CSU and the other fixed pitch timber.

There was barely a knot between them!

The CSU was slightly faster when wound right out.

[machtuk]

General Crz speed is not what CS is all about, it's about getting the HP avail from the get go, FP won't achieve rated HP from the start. Also CS better for Aero's. Lots of advantages hence they don't put FP props on a PA31...lol-)

[KRviator]

Mind you, a PA31, loaded to the gills needs every bit of HP it can get. Any RV with more than 160HP is massively overpowered. My -9A will get around 1800FPM with a FP prop and makes 145KTAS spinning at 2400RPM at 8500. Unless I was building a -10, I'd never waste the money (or the weight) on a CS prop.

[machtuk]

Mind you, a PA31, loaded to the gills needs every bit of HP it can get. Any RV with more than 160HP is massively overpowered. My -9A will get around 1800FPM with a FP prop and makes 145KTAS spinning at 2400RPM at 8500. Unless I was building a -10, I'd never waste the money (or the weight) on a CS prop.

like I said it's not about Crz speed with a CS prop it's about perf but my Vans will do 180 ktas WOT 8.5k and I can climb @2500fpm, the advantages of a conventional U/C, IO360 CS, the Std by a long shot -)....and I can aerobat all day long -$

[Fred Gassit]

100% agree with Mach, I’ve flown a few Vans and don’t regret my CSU one bit, love being able to takeoff in first.
Why is the prop so dear?
Vans price for my prop is currently 8.5k USD

[extralite]

Thanks everyone for the tips (get it..tips!) and especially Matchuk and Fred Gassit. I have sent the regulation Matchuk linked to and waiting to hear back on a reply. You may have saved me many 1000's of dollars. I have no idea why the prop is so expensive but i am guessing it has something to do with the prop shops (wont name name's) markup. The RV7's stable mate (Cessna) also needed a new prop apparently when sent off for its inspection as in that case the trailing edge out of limits, but the prop hadnt done much time at all.

As for the constant speed debate. I haven't tried a fixed pitch in anything other than a cessna, but i know my RV is extremely economical going from A to B at 8000-10000ft and I assume among other things that has to do with the prop operating at maximum efficiency. But without trying the same RV side by side who knows for sure and we all have our preferences.

Are there ways to get a new prop directly without the $25k price tag?

[mendi63]

Are there ways to get a new prop directly without the $25k price tag?

https://shop.vansaircraft.com/cgi-bin/shop.cgi?ident=1587515297-410-615&browse=props&product=csprop-hartzell

Prices start at US$8450.00 depending on the model

[poteroo]

I think we're all in furious agreement that the RV series are great performers, and do exactly what VANS states they will. If you are prepared to go CS - then there are advantages......but at a price.

For me, what made the greatest difference to my -9A performance in cross country ops was going with fuel injection, plus electronic ignition on the RH 'mag'. Fuel consumption can be stretched far better than the carby versions of the 180HP -360 engine. You soon learn how to hot start them!

happy RV ing,

[extralite]

So upshot is as MAtchuk pointed out, it doesn't need an overhaul. I am getting it disassembled and crack checked. That is still needed and obviously makes sense as well. So this thread has saved me about $20k. Thanks.

Not sure if VANS ships props to Aus as these things are often tied up in distribution agreements which is how local distributers can make such a high margin. But have asked.

[On eyre]

I think we're all in furious agreement that the RV series are great performers, and do exactly what VANS states they will. If you are prepared to go CS - then there are advantages......but at a price.

For me, what made the greatest difference to my -9A performance in cross country ops was going with fuel injection, plus electronic ignition on the RH 'mag'. Fuel consumption can be stretched far better than the carby versions of the 180HP -360 engine. You soon learn how to hot start them!

happy RV ing,

Yes - what he said.
Same as - 140 kts economy cruise @ 26L/hr.

[machtuk]

Yes - what he said.
Same as - 140 kts economy cruise @ 26L/hr.

i can achieve the same figures if I want (don't want to, fuel is the cheap part of flying) but I also can blitz the slower vans anytime I want!👍

[machtuk]

So upshot is as MAtchuk pointed out, it doesn't need an overhaul. I am getting it disassembled and crack checked. That is still needed and obviously makes sense as well. So this thread has saved me about $20k. Thanks.

Not sure if VANS ships props to Aus as these things are often tied up in distribution agreements which is how local distributers can make such a high margin. But have asked.

glad you found with what you are happy with. Crack testing isn't required either but that's yr choice. I left mine alone at the 10 year mark no point in fiddling with something that works just fine, on condition👍
Remember the whole plane is uncertified. Built by a backyard person, can be fitted with an auto engine or uncert aero engine, Inst/radios cab be bought in KMart, the prop is in the same boat👍 That's the whole idea of LS flying and experimental, to avoid the ludicrous expense involved in rip off Cert flying!

[megan]

Not sure if VANS ships props to AusThey certainly used to, engines as well, anything in their catalogue, but I'm going back a little more than two decades, don't see why things would have changed.

[Capt Quentin McHale]

Squawk7700,

"It’s your life (and your passenger) behind the prop!"

and me on the ground underneath it !!!!!!!

Rgds McHale.

[Cloudee]

Two mates of mine did simultaneous RV6 builds. One with CSU and the other fixed pitch timber.

There was barely a knot between them!

The CSU was slightly faster when wound right out.
What were the respective take off distances and climb performances? how much easier was it to slow down the CSU aircraft on approach? What were the fuel consumption figures at cruise speeds. How much is slightly faster when wound right out? Were these aircraft identical in all other respects?

There’s a lot to consider when choosing CSU or fixed pitch. I would not change the CSU prop on my 8, but fixed pitch may be more suitable for a lighter 9.

[machtuk]

What were the respective take off distances and climb performances? how much easier was it to slow down the CSU aircraft on approach? What were the fuel consumption figures at cruise speeds. How much is slightly faster when wound right out? Were these aircraft identical in all other respects?

There’s a lot to consider when choosing CSU or fixed pitch. I would not change the CSU prop on my 8, but fixed pitch may be more suitable for a lighter 9.

well said -) there will always be those that hate it when CS drivers sail right past the FP guys, right from the get go -) If there was only one knot between them then CS manufacturers would go out of business...lolol