Switching props

[alcladrv]

If I switch from the fixed-pitch Sensenich to a constant-speed Hartzell, can I just rework my current spinner on my -7A or do I need to buy and install the constant-speed spinner kit that Vans sells?

Thank for you input.

Mike

[N908RV]

I'm trying this from memory, but IIRC, the aft backplate/bulkhead and the f'glass spinner itself are the only two common parts between a CS and a FP spinner assembly.

I suppose you could order a new forward bulkhead and a CS aft bulkhead reinforcement piece. But, IMHO, it would be a whole lot easier to make a new one than try to salvage and re-use.

My 2c.

Rob

[Martin Sutter]

I did that switch on my 180HP RV6 a few years ago and would not recommend trying to use any of the fixed pitch parts. The whole set up of the cs prop is too different and the spinner cut-out not the same at all.

Martin Sutter
building and flying RV's since 1988

[dav1111]

Be sure and have either a DAR or the FAA FSDO do an approval of the prop change. It is my understanding that the airplane has to go back to Phase I flight testing after either a prop or engine change.

[carguy614]

Be interested to find out how much your numbers improve. Keep us posted eh...
Regards...Chris

BTW..Born and raised in Centreville Va. Understand it's a little bigger now!!

[sjhurlbut]

Changed my prop as well.

Order the Vans CS spinner kit. Backing plates, hardware, spinner, everything you need. The FP spinner and backing plate will not work.

Steve
RV7A

[pierre smith]

Originally Posted by carguy614

Be interested to find out how much your numbers improve. Keep us posted eh...
Regards...Chris

Chris,
Hard to believe but it may actually be slower. Takeoff and climb performance will be better but not top speed or cruise perhaps. The reason being that you cannot run a CS prop at 2700 cruise but a fixed pitch Catto and others can. More RPM=more horsepower. We outrun quite a few CS propped RV's

Regards,

[DickDe]

I did a prop change one year ago and did NOT call the FAA FSDO because of the following reasons. My "Operation Limitation Letter" given to me when certifying the aircraft, which I believe are all standard letters, has a paragraph on modifications and what the owner has to do. This letter is a mandatory written agreement between the aircraft owner and the FAA, signed by the FAA, at least through their DAR, and compliance is mandatory. It states that major modifications require the aircraft be placed back into phase 1 for a period of at least 4 hours (maybe 5?) to determine if any of the V speeds have changed and of any adverse flight characteristics. A notation is to be placed in the logs of the modification and that you have returned the aircraft back to phase 1 testing. Upon completion of the new phase 1, you again write in a statement verifying you have found the aircraft safe and returning it back to Phase 2 operation. All the actual wording is in the Operation Limitation Letter so don't do what I have decribed but rather do what your letter says.

Prior to the modification I did ask at least 4 FSDO inspectors, most at EAA OSH, if I needed their approval for the change. Since I am a retired FAA person I found it best to ask the same question to many people but read the regulations because most of these guys do not really know the regs, then make your own decision. The answer ranged from "yes, we will revoke your certificate of airworthiness and reissue a new one" to "call us, we will reinspect and give you a short test period". All wanted to get envolved and some with a not too user friendly attitude. A phone call to my DAR, who is also a friend, confirmed my decision to follow the Operational Limitations Letter. He affirmed my thinking so I changed the prop without advising the FAA at all making the change simple (and "legal").

Dick DeCramer
RV6 N500DD 220 hours
RV8 wings
Northfield, MN

[jclark]

Originally Posted by dav1111

Be sure and have either a DAR or the FAA FSDO do an approval of the prop change. It is my understanding that the airplane has to go back to Phase I flight testing after either a prop or engine change.

The plane has to be put back into "Phase 1" for at least 5 hours of testing in the new configuration after a "major modification" (Prop change is considered major). After discovery of no adverse operating conditions, it is then put back into "Phase II".

James
... been there

[Rosie]

Originally Posted by dav1111

Be sure and have either a DAR or the FAA FSDO do an approval of the prop change. It is my understanding that the airplane has to go back to Phase I flight testing after either a prop or engine change.

Originally Posted by jclark

The plane has to be put back into "Phase 1" for at least 5 hours of testing in the new configuration after a "major modification" (Prop change is considered major). After discovery of no adverse operating conditions, it is then put back into "Phase II".

James
... been there

Both Russ and James could be correct...but that depends on what your operating limitations say. I switched from FP to C/S prop in 2005. My operating limitations (dated June 2000) did not allow me to do what James described as the verbage allowing this was not included.

I contacted the local FSDO and their response was to issue me new operating limitations. The new limitations had the verbage to allow me to remove my fixed pitch prop, install the constant speed prop then put the plane back into Phase I for at least 5 hours flight testing (all done with complete annotations in the log books).

All FSDO contact was done via phone and snail-mail as I had to send in a copy of the limitations issued to me Rosie