C20B or C20R

Holden · November 30, 2003

Pros and cons to both of these? Is one more reliable more than the other? Thanks

HeliMark · November 30, 2003

Depends on if you want to work it in the higher altitudes. The "R" is suppose to be the altitude version of the "B". I fly a 500E with the "R", and you will see a difference in performance until you hit about 2-3'K. Then the difference is minimal. It will give you about 5-10 degree's more on hot days, but remember the torque has the same limitations. We have a 500D with the "B" and it runs rings around the others.

As far as reliability, we have not seen any difference.

If you do get the "R" engine, a must is the digital TOT. Gives you higher temp limitations over the analog gauge (especially in the transient area). Well worth it.

Randy Greenhalgh · December 2, 2003

Never been a fan of the R in a 500. We had a few E models with the R, and the D's with a B would lift the same load. We found the R's to not last like B's, and used a little more fuel. Now, I have heard good things about the latest variant the R+. With an extra 30 shp, there should be significant temp/alt differences to a/c with the 20B.

Cheers

helofixer · December 5, 2003

If I am not mistaken, the R+ engine is just an R engine that is gauranteed 5% above a minimum spec engine. There "should" be some benefits to this at altitude, but at Helimark says the jury is still out on the whole "R" deal. A benefit of the R+ is that if you start with an above spec engine, then it takes longer to get to the stage where the engine goes below spec and needs work.

The major problem with the R seems to be that a lot of these engines are plagued with turbine lock-up.

HeliMark · December 7, 2003

We have the R+ engine in one of our NOTARS :crutches:. There is a pretty sizable difference on the TOT on hot days. Enough to justify it if you work in that environment. I have not flown one on a "E" model, but I am sure you would have up to 15-20 degree's more to work with in it. That is significant to me.

Our R+ engine has 1,500+ hours and although like any engine not new anymore, but there is still a big difference with it.

As far as maintenance on the R/R+, as a pilot, I always see two things. One is that the gasket between the starter/generator and its mounting pad always starts leaking by 50 hours after replacement. Second is like what helofixer says. They like to coke up. Especially if you base them at a higher altitude. We do three minute cool downs instead of the book two minute ones and that helps alot. Also turn the blades backwards three or four times at the end of the day really helps.

Randy Greenhalgh · December 8, 2003

A 500 engine leaking ?? I used to get worried if I didn't see a little oil on the clam-shells after a flight. Because of the trapped heat in the engine bay, and the angle of the engine, the starter gen seal, or gasket tends to weep oil almost all of the time. Out of over 2K hrs in the things, I think the engines wept oil for 1990 of them. ::

An interesting aside. I was at HAI one year talking with an engineer from P&WC, about how it would be great to have a Pratt in a 500. He said that they had been approached by Mac Doug, Boeing, for such a thing, but P&WC wouldn't let them mount the engine on an angle. They were thinking of using either a small PT6, or the new (at the time) 200 series of around 500hp. That would have been a great combination IMO. Too bad it never happened.

Cheers

Flying Pig · December 20, 2003

Helimark.....

Why do you turn the blades backwards after shutdown?

HeliMark · December 20, 2003

It seems to help reduce the coking problem. When I get a bird that already is coking up, and doing the backward turn, within several days I see a big improvment. I also do it on preflight if the engine is coked up pretty good. Really helps.

I do not know if there is any technical reason for it to work, but our chief mechanic told me to do it, and it works.

Heloflights · December 23, 2003

The factory school stresses the one full backwards rotation after shut to prevent the N2 blades from coking up, we have always done this, especially during the summer months.

Gets a little tougher for the NOTAR guys not having a TR to grab a hold of...

On the subject of engine oil leaks - we notice droplets on the cowl doors after each flight that vary as a function of temperature, the hotter the weather, the more oil we see. Our burns are still running 30-40 hrs/qt however.

Flying Pig · December 26, 2003

Helimark....

I am still fairly new at this....What is coking?

Flying Pig · December 26, 2003

Nevermind........

A little internet research next time prior to asking questions never hurts.

MD500 · September 1, 2005

Coking is A high carbon content solid residue from oil ... I.e... Hard crusty carbon deposit from the oil breaking down. Can cause all kinds of problem inside the engine. Ensure that you are using third generation turbine oil like Aeroshell 560 or Mobil 254... Forget the old Mobil Jet II. Turning the blades backwards only stops the build up. It doesn’t prevent it... The third generation oil will... Any questions fee free to call us. Phoenix Heliparts. Mesa AZ 480-985-7994