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If you were buying an RV-4 ...

H

Hangar 1271

Well Known Member
What are the questions you would ask?

What equipment really makes a difference (ignitions, prop, engine, gear)?

The upgrades, versions, changes that are important?

What particulars need to be avoided?
 
I've been involved with a couple of RV-4s. I like the simple ones with fixed pitch prop and a plain panel.
Check the weight and balance. pick the lightest one. under 900 is good. Over 1000 is not-so-good. Calculate a few load scenarios; Pick one with a rear seat weight limit about 180 pounds or better (if you can)
Check for build quality, like smooth wing skins, and thin paint. Lots of thick flooded on paint makes a pretty plane, but adds weight & covers unsightly defects.
A smooth straight aircraft with thin paint is good. A trim tab on the rudder is OK, but aileron trim tabs might mean the wings are not in alignment, or the ailerons don't match. Ailerons aren't hard to alter, but when you're buying, get a good one.
Check the forward longeron weldaments where the engine mount bolts attach at the firewall; these should be crack free, and hopefully the later, beefier version.
Check the landing gear, some have been landed too hard or ground looped. One gear may be farther aft than the other. drop a plumb bob down from the leading edge of the wing at the tire, and measure the distance from the string to the center of the wheel bearing nut. These should measure the same, or within 1/2"?
Total Airframe & Engine hours matter. Same with Engine time since overhaul.
There is a start. There is a lot more, other posters will have good tips...
 
David, looks like you are new to the forum. Use the search function. This topic has been discussed in great detail and is archived.

Btw, i have never heard of a -4 to be less than 900 lbs. even vans numbers are higher than that.

Good luck if you are purchasing a -4. They are awesome planes.
 
My initial list

When I'm looking at a -4 to possibly purchase, I like to get answers to these questions up front. Some (not all) are deal-breaker questions:

1) Plans built or kit?

2) What is the Empty Weight?

3) Long gear legs or short?

5) Is there a:

Crash History?
Damage History (e.g. firewall bending hard landings)?
Fire History?

6) What thickness aluminum used on the elevator skins?

7) Footwells in back?

8) Have all relevant Service Bulletins been applied?

9) What is the full engine specification (if not specified in the ad)?

10) Any rpm limitations in addition to the stock engine specs?

11) Day only or Day/Night VFR?

12) Year built or kit year vs certification year.

13) Full prop specification


Just the other day I was looking at a C/S propped -4. The ad says it has a Hartzell HC-C2YK-1B – 1 hung on an O-360 A1A. Nice.

But I did a search on that prop to get it's diameter and found this:

-----------------------------------------------
Hartzell HC-C2YK-1BF/F7666A-2 Propeller on 180 Hp Lycoming engines
equipped with Electronic Ignition or FADEC

The Hartzell Propeller Model HC-C2YK-1BF/F7666A-2 has been vibrationally approved per FAR23.907 on the standard production Lycoming Engine Model O-360-A1A, and similar models,rated at 180 HP at 2700 RPM with a restriction to avoid continuous operation between 2000 and 2250 RPM.
---------------------------------------------------

This came from:

https://www.vansaircraft.com/pdf/Hartzell_c2yk.pdf

There's another PDF on this here:

https://www.vansaircraft.com/pdf/Hartzell_c2yr.pdf

I'd have to investigate this further but would be a deep concern that I can't run continuously at 2100 rpm.

My list grows as I learn more about what to look for. And I have to say that the more I look, the more an O-320, 160hp, wood prop sounds best. Unless it has long landing gear legs in which case I'd consider a bigger prop.


There is an article in a recent Kitplanes that talks about 35 years of the RV-4 and there's a section that talks about what to look for when buying a used plane.

Hope this helps.
 
FWIW I have the Sensenich metal prop on my short legged RV-4 and it works just fine...
 
My -4 weighs 1040 lbs, will outperform all 14 RV's on my airfield, and flies like a dream. IO-360 with a CS prop is how these things should have been designed from the get go. Also, an aileron trim tab is nice to have if you plan to do XC. Helps to keep the plane trimmed to hands off as fuel burns unevenly.

Alex
 
Check the tanks for slosh. It will cost about $1500 plus shipping to get it cleaned out and re-sealed.
 
Know your mission first

As a -4 builder/owner, I have given much advise to future buyers. Mine is 940 lbs,Long gear, 160 hp, fixed wood prop, footwells and electric flaps, aileron and elevator trim. Steam gauges and day/night VFR. Fits my mission 99% of the time. if you are looking for IFR, glass and other additions, your mission may be different. If you want to buy and fly, know your mission, if you want to buy and upgrade/downgrade, most of the key points have been mentioned. None are deal breakers, just things to ponder. switching from short to long gear isnt a quick mod, and cleaning tank slosh is a real pain for most. Rear footwells are easy to add and a dream come true for the backseater. Feel free to ask me any questions.
 
rbibb said:
I was just pointing out that long gear legs are required to use one...
Click to expand...

Yeah that's my point as well when I wrote:

" And I have to say that the more I look, the more an O-320, 160hp, wood prop sounds best. Unless it has long landing gear legs in which case I'd consider a bigger prop."

In other words if it has short legs then I might be inclined to go with the shorter diameter props. Longer leg? Larger dia prop.
 
Saville said:
Yeah that's my point as well when I wrote:

" And I have to say that the more I look, the more an O-320, 160hp, wood prop sounds best. Unless it has long landing gear legs in which case I'd consider a bigger prop."

In other words if it has short legs then I might be inclined to go with the shorter diameter props. Longer leg? Larger dia prop.
Click to expand...

Actually I was a victim of spellcheck autocorrect. What I meant to type was that the Sensenich Metal Prop (70" diameter) works fine with my short leg RV-4 so the long gear, while nice to have, is not a requirement to use that prop....
 
Saville said:
Just the other day I was looking at a C/S propped -4. The ad says it has a Hartzell HC-C2YK-1B ? 1 hung on an O-360 A1A. Nice.

But I did a search on that prop to get it's diameter and found this:

-----------------------------------------------
Hartzell HC-C2YK-1BF/F7666A-2 Propeller on 180 Hp Lycoming engines
equipped with Electronic Ignition or FADEC

The Hartzell Propeller Model HC-C2YK-1BF/F7666A-2 has been vibrationally approved per FAR23.907 on the standard production Lycoming Engine Model O-360-A1A, and similar models,rated at 180 HP at 2700 RPM with a restriction to avoid continuous operation between 2000 and 2250 RPM.
---------------------------------------------------

This came from:

https://www.vansaircraft.com/pdf/Hartzell_c2yk.pdf

There's another PDF on this here:

https://www.vansaircraft.com/pdf/Hartzell_c2yr.pdf

I'd have to investigate this further but would be a deep concern that I can't run continuously at 2100 rpm.

.
Click to expand...

When I built my -4, I bought the engine and prop combo referenced above from Van's. It was a fairly common combo 14 or 15 years ago. I lived with the rpm restriction without any issue. I have since purchased the new "blended airfoil" prop and now run it on the same engine without rpm restrictions. According to Hartzell, it has no rpm restrictions not because it is a better match to the engine, but because no testing has been done. I'm not sure if this is better or worse than the previous combination...

Regards,
 
Saville said:
Just the other day I was looking at a C/S propped -4. The ad says it has a Hartzell HC-C2YK-1B ? 1 hung on an O-360 A1A. Nice.

But I did a search on that prop to get it's diameter and found this:

-----------------------------------------------
Hartzell HC-C2YK-1BF/F7666A-2 Propeller on 180 Hp Lycoming engines
equipped with Electronic Ignition or FADEC

The Hartzell Propeller Model HC-C2YK-1BF/F7666A-2 has been vibrationally approved per FAR23.907 on the standard production Lycoming Engine Model O-360-A1A, and similar models,rated at 180 HP at 2700 RPM with a restriction to avoid continuous operation between 2000 and 2250 RPM.
---------------------------------------------------

This came from:

https://www.vansaircraft.com/pdf/Hartzell_c2yk.pdf

There's another PDF on this here:

https://www.vansaircraft.com/pdf/Hartzell_c2yr.pdf

I'd have to investigate this further but would be a deep concern that I can't run continuously at 2100 rpm.

.
Click to expand...

When I built my -4, I bought the engine and prop combo referenced above from Van's. It was a fairly common combo 14 or 15 years ago. I lived with the rpm restriction without any issue. I have since purchased the new "blended airfoil" prop and now run it on the same engine without rpm restrictions. According to Hartzell, it has no rpm restrictions not because it is a better match to the engine, but because no testing has been done. I'm not sure if this is better or worse than the previous combination...

Regards,
 
Thanks so much for the input. Always helpful to get the insight of experience. I searched previous threads on the subject as suggested. It is interesting to see the progression of opinions over the 9 year span of threads.
 
I had a 72" Hartzell on my short-legged -4. Given this was my first taildragger and I had not flown an RV previously except for transition training, I had some interesting landings but never touched the prop.

If I were buying another -4 I would definitely get the long legged version as it is much closer to the critical AOA in the landing attitude - reduces the number of tailwheel first arrivals.
 
SMO said:
If I were buying another -4 I would definitely get the long legged version as it is much closer to the critical AOA in the landing attitude - reduces the number of tailwheel first arrivals.
Click to expand...

I have a short legged -4 and almost every 3 point landing has the tailwheel touching first. It's not a bad thing and I believe it's the way it was designed (not sure why). With that said, the long legged version is sexy and I would buy that if possible but definitely not a deal breaker.
 
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