IO-550 Ovation Engine Sag

[Txbyker]

I have noticed about a 1/2" difference from the top of my cowling and spinner alignment versus the bottom. I have read previous post but could not see any direct answers about how to correct this in an Ovation. I have heard the engine lies in a cradle. My MSC said it couldn't really be shimmed. You can lift the spinner and engine up 1/2" and I have been told it will center in flight. Just wondering what some of you have done for this in a Continental IO-550.

Russ

[carusoam]

Is it a real obvious 1/2", Russ?

I think mine is pretty well centered. But if I would have to measure it to see the difference, I have not noticed it before. I've looked quite a bit.

I have less than 100 hours on the mount and new biscuits supporting the engine.

The best I can tell is the big beautiful spinner is not really designed to match the nice flowing cowling.

Are you measuring the shaft vs. the hole in the cowl?

Previous experience includes... My M20C broke an engine mount. The prop would sag about 1/2" but not very noticeable.

Then on another day it was not sagging at all.

One of the supports had broken a welded joint. Depending on how it shut down, it would align and be unnoticeable, or not align and drop a 1/2"

I briefly thought it may have fixed itself, that couldn't make sense so into the shop it went....

Let me know how you measure it, I'll compare notes if there isn't better guidance.

Best regards,

-a-

[Txbyker]

Yeah, I'll measure it. Just guessing top cowling definitely more fiberglass showing than bottom. From the side view I can probably stick a finger in the gap, maybe. I have an IA hangar next to me that specializes in BO's and he thinks it should be centered.

[Danb]

My Bravo should be similar, Ill check it out in the am and if not centered get back...

[Cruiser]

I check mine after a flight today. It looks pretty well centered in the opening of the cowl. Equal both top and bottom.

[Guest]

Either the engine is sagging, or the cowl is riding higher hence the mis-match. Front engine Lord mounts may be compressed somewhat. If all is OK there is really no reason the front mounts could not be shimmed, a few spare Lord mount washers and a longer set of front bolts should be fine.

I would also suggest looking at the lower cowl from rub damage from the exhaust system.

Clarence

[Andy95W]

I just finished the annual work on a friend's 2008 Ovation 3 and his spinner is also about 1/2" below the top of his top cowling, just like you describe. He said his was like that from the factory (he picked his up brand new) and the factory guys told him the same thing: it will center in flight.

IMO I wouldn't worry about it, just keep an eye on the engine mount and rubber Lord mounts, just in case.

[VetRepp]

My Ovation 2 is the same way - I questioned it and was told it likely centers in flight. I have no way to know. I am curious to find the answer and whether it was designed that way.

(If it wasn't designed that way, it seems like it would cause unnecessary drag and less than optimal aerodynamics and fixing it should be worth ... 1/2 knot cruise speed.  ;-)

[Txbyker]

Here is a pic of my spinner and cowling. 

 

Russ

[jetdriven]

Check if the cowl is riding up. If not, that engine is sagging. Look at the gap behind the spinner at the top and the bottom. It is quite a difference in measurement.

[M20S Driver]

My Ovation 2 is the same way - I questioned it and was told it likely centers in flight. I have no way to know. I am curious to find the answer and whether it was designed that way.

(If it wasn't designed that way, it seems like it would cause unnecessary drag and less than optimal aerodynamics and fixing it should be worth ... 1/2 knot cruise speed. ;-)

My Eagle is 3-4 knots faster after I installed new mounts and aligned the prop to cowling. It was sagging about 1/2 inch to 3/4 inch.

Masoud

[VetRepp]

Russ on mine, I have no difference in distance from Spinner to Cowl spacing on top or bottom but the smooth  lines of the spinner to cowl is like yours with a stair step in the airflow from the top of the spinner to top cowl

[Txbyker]

Masoud, do you know how difficult that was? Wondering if you watched or may have participated in the install. I may do this with an IA I know.

Russ

[M20S Driver]

Masoud, do you know how difficult that was? Wondering if you watched or may have participated in the install. I may do this with an IA I know.

Russ

Russ: It was pretty easy. I saw them do it but did not participate. They did one engine mount at a time and used some extra washers and longer bolts for the front mounts.

Masoud

[N177MC]

This is interesting since it's the first time I've heard of anyone "shimming" up the big bore engine. 

 

I look after a Scream'n Eagle and I keep telling the owner we need to do something about the engine sag - it's closer to 1" than 1/2".

 

I own a Centurion T210 and Cessna has an SB where they call out he use of longer bolts and heavy washer under the from mounts to correct any sagging so I was thinking same for the Mooney.

 

Do you have the p/n for the washers please ?

[M20S Driver]

The washers were regular SS washers similar in size  to the one on the engine mount.  The bolt was NAS1307-52. 

 

Masoud

[kmyfm20s]

Are there any specs for the correct height? Every Ovation/Eagle I've seen the spinner has been a 1/2" to 5/8" below the cowl.

[M20S Driver]

Are there any specs for the correct height? Every Ovation/Eagle I've seen the spinner has been a 1/2" to 5/8" below the cowl.

We used the cowling as a reference to center the prop. With new engine mount, it was about .25 inch off.

[Cruiser]

This is what mine looks like 

 

 

 

 

[Txbyker]

This is what mine looks like 

 

 That looks pretty good!

[Txbyker]

I spoke to Dugosh yesterday and was told that the Ovation engine position is set by the factory and there is really no adjustment available. Some sag worse than others according to them and is normal per Mooney...according to the MSC.

Russ

[aramkis]

Hello,

I realize that this original post is quite dated; however, I wanted to determine what others have done and who they have used to correct their issue with a sagging engine on their Ovation. I have a 2004 Ovation 2 that I have owned for about two years. I noted when I purchased the airplane that the engine was sagging about 3/4" low below the top of the cowling (that is in relation to the top of the spinner). But as there was no risk that the spinner would touch the cowling in the near future, I decided to wait to have this addressed at my first annual.

I had my A&P replace all four mounts; however that did not change the location of the engine in relation to the cowling. I read in this, and other threads, that there is a belief that the engine will center in flight, but I have attempted to lift the engine following the mount replacement and there is no play; therefore, I have doubts that it could ever center. 

Anyway, my A&P is not comfortable with shimming the engine with mounts as he could not find anything official in SBs in order to do that work. And since I am not comfortable with leaving it as is, I was just wondering if there was anyone in the southeast Florida area who had this issue and then had it addressed by a MSC or knowledgable A&P who they could recommend.

Andrew

[StevenL757]

If there is no apparent risk that any piece of the cowling would touch any part of the spinner backplate or prop, then I'd leave it alone.  The fit of the cowling itself may be the culprit, as opposed to the way the engine sits on the mounts.  As Clarence @M20Doc pointed out (and my IA indicated similarly), if it really bothers you to have it visually sag, you could add washers and longer bolts to improve the appearance.

[aramkis]

15 minutes ago, StevenL757 said:

If there is no apparent risk that any piece of the cowling would touch any part of the spinner backplate or prop, then I'd leave it alone.  The fit of the cowling itself may be the culprit, as opposed to the way the engine sits on the mounts.  As Clarence @M20Doc pointed out (and my IA indicated similarly), if it really bothers you to have it visually sag, you could add washers and longer bolts to improve the appearance.

Hello StevenL757,

I appreciate your timely response. I tend to agree with you, Clarence, and your IA in that 'if it isn't broke, don't attempt to fix it' approach.

However, it is certainly a visual concern and it is hard to believe that I am not losing a knot or two from the drag that is caused by that very blunt front of the cowling that does not benefit from having the spinner create a smooth airflow over and around it. I will need to take and post a picture of just what my sag looks like, but suffice it to say that it is very similar to what the OP, Txbyker, posted on June 2, 2014 (earlier in this thread).

I was hoping that there would be a bulletin/guide or a knowledgable IA in my area (southeast Florida) that would be willing and able to add the spacers to align the engine with the cowling, if for no other reason than to address the unsightliness of having blunt edges within such a streamlined airframe.

Andrew

[jetdriven]

The spinner does not center in flight. George Perry proved this out