New top end, bad ground-run RPM

[Yukon]

Originally Posted by brenegan

I disagree. Yes, it's insufficient to break in the cylinders; About an hour or so
of flight and you'll probaby start seeing the CHT rise and then drop to 'normal' levels; but if you are not getting what's specified in the TCDS you shouldn't fly. A full power runup to check RPM is not going to cook the cylinders.

The TCDS make no accounting of the prop installed, only the RPM at which rated hp occurs. Fixed-pitch props will indicate much lower than TCDS RPM, even if they aren't sporting new cylinders. PS : You are way wrong about full power runups, JUST SAY NO!

[brenegan]

Originally Posted by Yukon

The TCDS make no accounting of the prop installed, only the RPM at which rated hp occurs. Fixed-pitch props will indicate much lower than TCDS RPM, even if they aren't sporting new cylinders. PS : You are way wrong about full power runups, JUST SAY NO!

Not so. Read page 7 of the ECI recommended break-in procedures. I didn't say mag-check or extended run at full power, only to verify takeoff power is available. I provided you a link so all you have to do is click .

[bucaronco]

Sorry guys...

I forgot to mention that it's a fixed pitch prop, which is why I was suspicious of the TACH rather than the prop/governor...

I agree that ground time should be held to a minimum on new cylinders, as does my A&P. He has mentioned several times that a "ground breakin" will not seat the rings. The installation instructions directed the A&P as to how the ground run should be conducted, and it said to do a run to full throttle, keeping oil temp and pressure below certain levels.

Thanks to threads on this site, and previous discussions on setting rings, I've already made arrangements to tow the A/C to the runway, crankup, warmup and go, to get the cooling flow over the cylinders.

I'm still reading-for-effect the "Break-in Instructions" which I D'loaded from the ECI website. I'll follow them to a T on the first flight, but first pass over them shows a direction to "keep power at top of the green arc on the tachometer and manifold pressure gauge or 74% power (whichever is higher) for 1/2 hour." ....thus my concern that the tach'd RPM was an accurate number, AND not evidence of a lurking problem that someone on here may have knowledge of.

I appreciate the reassurances of what's normal, as I get ready to exercise my right stuff.

[brenegan]

Another option on the tach is to get an external one you point at the prop. I have this one: http://aircraftspruce.com/catalog/inpages/onetouch.php and it's a piece of ****. There are others and maybe you can borrow one from someone to confirm the one on your instrument panel is reading correctly.

Good luck and be safe.

[Stephen Lindberg]

Agree with John on the undesirability of full power ground operations with new cylinders. Don't do it. At all.

The type data sheet will specify max and min ground static rpm for a fixed pitch propeller, and that is different than the max rpm for full power. For my PA-12/0-290D it is max 2450 static and min 2350 static. Max rpm in flight is 2600 (125 hp) on the data sheet. The metal plate on the engine says max continuous 2600 for 125 hp, five minute max 2700 for 130 hp. I'm not sure why full power is limited to five minutes on this model Lycoming but that is fine with me. I can hit 2700 in level flight but that puts my airspeed about half way into the yellow. I see about 2450 WOT in a 70 mph climb. BTW, when I broke in this engine I had a prop with too much pitch. After the engine was broken in and I had a reading on static rpm and max rpm in level flight, the prop shop took out a few inches of pitch and put me right in the middle of the static rpm range and right at max rpm in level flght.

[Tram]

Originally Posted by bucaronco

I appreciate the reassurances of what's normal, as I get ready to exercise my right stuff.

I'm sure you'll make us all proud..

[Mark Burns]

Originally Posted by Mark Burns

If you have a fixed pitch prop the static RPM is good.

If you have a constant speed prop you might need a new mechanic.

Mark

Ron,
My previous post was meant to be funny, but now doesn't seem so.

I just bashed your mechanic and offered little information.

I'm sure your mechanic is a good one. And now that I've learned he is retired Air Force I feel even shorter.

It looks like the other guys here have given you some good advice.

If I might add one thing, I don't think one full power run-up lasting 10 -15 seconds will glaze the cylinders. That's just my opinion, I have no data to back it up.

Mark

[bucaronco]

Thanks Mark...

I figured that the mechanic slams were BB humor, but felt compelled to defend him anyway. He has been verrry meticulous in his approach to the condition inspection, and I have his bill to *prove it*! However, Tram and I (my son)...he has much more time in it than me... are the fliers of this machine, and we welcome the fine-tooth approach, within reason. The mechanic who did last year's CI didn't even check the ELT batts !

314L's builder did a fine job on the airframe and fit and finish. It flies like a dream, and we're hoping that the new jugs will make it even more fun to fly. Jeff
has interior makeover ideas for it too, but this lil evolution has put those off for a while.

It's good to have this board for hangar talk before the first flight

[Kevin Horton]

Originally Posted by Stephen Lindberg

Type data sheet will specify max and min ground static rpm for a fixed pitch propeller, and that is different than the max rpm for full power. For my PA-12/0-290D it is max 2450 static and min 2350 static. Max rpm in flight is 2600 (125 hp) on the data sheet.

Engine Type Certificate Data Sheets (TCDS) won't specify a minimum static rpm, as that depends on the prop that is installed. An aircraft TCDS might specify a minimum static rpm, but there are no TCDSs for RVs, as they don't have type certificates.

[Stephen Lindberg]

I was quoting from my aircraft (PA-12) type data sheet, sorry I didn't make that clear. BTW, I think that my 0-290D max five minute rpm is 2800, not 2700 as I previously stated. That's not on the aircraft data sheet, but on the metal data plate mounted on the engine case, and I was going by memory. I don't know, but I'll bet with all the pitch required by an RV to go fast that ground static rpm is pretty low. Maybe 2000? Anybody care to comment?