Ovation Pre-Buy - Speed question

[Ed de C.]

Good afternoon folks - I recently put a deposit down on a 2008 Ovation 3 and yesterday rode along on the ferry flight from Oshawa Ontario to Chautauqua NY where the pre-buy and import process will occur.  This is my first aircraft purchase and as luck would have it, the plane that checked all my boxes is an import project.  I've got a purchase agreement that spells out who will do what for import, and following advice elsewhere, both the Canadian broker and the NY shop have import experience and will arrange most of the details.

During the ferry flight yesterday, I ran the Savvy flight tests for GAMI lean spread and in-flight mag check.  Both seemed straightforward and the data is filed for analysis.  The autopilot flew a coupled RNAV LPV approach without problem.  All other G1000 and aircraft systems seemed to operate without problem and the ferry pilot agreed that the plane handled normally (he has extensive experience flying Mooneys.  

Examining the data logs this morning for yesterday's flight and several prior flights, I'm finding the TAS seems to be consistently 7 to 10 knots slow compared to the POH.  Is this within the range of "normal" in your experience?  Here are some related points about the airplane:

• It has TKS installed from the factory.  I know the TKS drag costs us something, but do you think this much?
• The plane is dirty - plenty of oil/grease on the belly - it needs a good washing and detailing.
• The damage history includes a taxi prop strike a year ago (owner hit a taxi sign when the seat slipped backwards, and he could not reach the pedals).  Prop was replaced and engine overhauled along with cowl repairs.
• There was a minor tail strike recently, the damage appears limited to the tail skid and a piece of sheet metal the tail skid attaches to.  The damage is hard to discern (not obvious).
• I'm referencing the POH for the Ovation 2 GX I found online which lists the Hartzell 3-blade prop (PHC-J3YF-1RF) and 280 hp.  This Ovation 3 has the Hartzell 3-blade prop (same part number) and 310 hp.  
• Flight logs I examined occurred at altitudes ranging from 3,500 to 9,000 feet at 55% - 65% power.  
• I noticed that the flaps in retracted position are not tight to the upper trailing edge of the wing so that air can flow from the underside through the gap.  This plane does not have flap gap seals.  Another Ovation 2 I looked at recently exhibited a tight fit between the flap and the wing upper trailing edge so that no air (or very little) would leak through.  This makes me wonder if gap seals would be worthwhile in my case or if a flap adjustment is called for.

I've noted my speed observation for Savvy (and the shop).  Since the pre-buy will start on Monday and be followed by an annual inspection and DAR signoff of the airworthiness certificate, now's a good time for me to set my speed expectations and/or coach the shop to investigate.  

Ed

[Niko182]

what speeds and fuel flows did you see?

[mike_elliott]

There is about a 5-7 kt give up for tks in the ovations at 10k 100 ROP vs non tks from what I have observed. 

If this is the plane Clarence has been maintaining, I'm sure it is in rig, otherwise, you might have your prebuy shop put the travel boards on it and make sure it's in rig

 

[GeeBee]

I have an Ovation 2 GX 280hp with TKS. I run it at 65% LOP 12.4 gph between 9000 and 11000 I true 167 knots. If I go to 75% ROP 7000 feet, I true about 175-176 knots. Hope that gives you a reference.

[Brandt]

I believe the POH numbers are achieved without antennas or steps, with very little gas in the tanks etc, to maximize the speed.  

My plane is 8-10 kts off book and it doesn’t have TKS. But I have two steps, each costing a knot or two, and usually run close to max gross.  So I don’t think there’s anything wrong with your soon to be plane.  Have fun. 

[Ed de C.]

Thanks Niko182 - Here's the chart.  

[1980Mooney]

26 minutes ago, Ed de C. said:

Good afternoon folks - I recently put a deposit down on a 2008 Ovation 3 and yesterday rode along on the ferry flight from Oshawa Ontario to Chautauqua NY where the pre-buy and import process will occur.  This is my first aircraft purchase and as luck would have it, the plane that checked all my boxes is an import project.  ...Here are some related points about the airplane:

• There was a minor tail strike recently, the damage appears limited to the tail skid and a piece of sheet metal the tail skid attaches to.  The damage is hard to discern (not obvious).

The "sheet metal" is just thin aluminum with little structural strength.  The "tail skid" - 530187-001 is attached to a stiffener plate inside the "sheet metal".  If the exterior sheet aluminum is bent in, then the internal structure is bent.  You need to look at that closely.

[Danb]

Since you’re only 7-10 knots off book, which are done with a new perfectly rigged plane without TKS and as mentioned by the above three posts you’re good. Clean waxed in-rig planes will make a difference. Also weight plays a roll, my Bravo was 4-6 knots slower at gross than my landing weight after burning 80-100 gallons.

[Ed de C.]

Indeed, this is a Maintained-by-Clarence aircraft.  (He might want to trademark that.)  Having spent a couple of hours with Clarence at his shop the day before the ferry flight, and seeing the travel boards attached to another Mooney, I've no doubt this is a clean airplane.  Based on what a couple of you have already indicated, I'll attribute the speed discrepancy to an optimistic test protocol at Mooney.  

I must say, what a fantastic airplane!  Even flying right seat on the ferry flight, that was a lot of fun.  That engine pushes all the right buttons.  

[ilovecornfields]

52 minutes ago, GeeBee said:

I have an Ovation 2 GX 280hp with TKS. I run it at 65% LOP 12.4 gph between 9000 and 11000 I true 167 knots. If I go to 75% ROP 7000 feet, I true about 175-176 knots. Hope that gives you a reference.

This is pretty much what I get for my TKS O2. The TAS is usually 100 + %power - 150 kts at 50%, 160 at 60%, 170 at 70%, etc.  I usually fly 50%, 10.5 GPH 

[PT20J]

Hard to tell about the flap gap without a picture, but I have seen several where the flaps are too tight and the rivet heads on the flaps are worn down because the rub the bottom of the wing skin. 

[RoundTwo]

51 minutes ago, PT20J said:

Hard to tell about the flap gap without a picture, but I have seen several where the flaps are too tight and the rivet heads on the flaps are worn down because the rub the bottom of the wing skin. 

Yeah, I’ve got that issue. Is there a spec on a specific gap that needs to be set?

[Schllc]

Every one I have flown has been a little different, and a couple were real outliers. 
I’ve seen more than a few guys claim they get 190knots at 11gph lop in their ovations. I personally never saw anything like that, and I have flown quite a few.
The numbers you are seeing are in line with my experience. 
There are a lot of small things that can affect drag, and the conclusion I have come to is that some airframes are just truer and faster, and some are slower. 
I had one that was a real dog, so slow I was convinced the rigging was out.
It was an acclaim that was over 10knts off the others I had flown. I brought it back to the factory to check the rigging and all was good.  Some are just faster than others…
 

[PT20J]

1 hour ago, RoundTwo said:

Yeah, I’ve got that issue. Is there a spec on a specific gap that needs to be set?

A trick Don Maxwell does if the flaps still rub when adjusted to spec is to put the flaps down slightly to open the gap and then place a thin piece of wood on the flap nose and insert a stiff putty knife between the wood and the wing skin and gently flex the wing skin upward working slowly along the entire length of the flap The skins are thicker near the root so it takes more flexing, and the skins will spring back quite a bit, so it takes some experimenting. Just go slowly. It doesn't take much of a gap to clear the rivets.

[Fly Boomer]

5 hours ago, Ed de C. said:

Examining the data logs this morning for yesterday's flight and several prior flights, I'm finding the TAS seems to be consistently 7 to 10 knots slow compared to the POH.  Is this within the range of "normal" in your experience?

I don't know what is "normal" for an O3, but my observation is that not many airplanes can match book speeds.  Now that I have stepped out, I'm sure I will be inundated with "my airplane is faster than book" posts.  Similarly, not many 201s will hit 201 MPH, not many 231s will hit 231 MPH, not many 252s will hit 252 MPH, etc.

[GeeBee]

Having been involved for years in fleet operations, they all have some variance. The worst was the DC-9's which were like a box of chocolates. The most consistent is Airbus. Airlines have to keep historical data on each ship and its performance and every airplane has a "plus and minus" from the book standard which is accounted for in the flight plan software by ship number. Lockheed always had the highest percentage "plus airframes", Airbus the most "at book" and Douglas the most dogs. Some of that is engine, some is airframe, but when you look at new airframes with new engines, the percentages seem to hold. Usually wide variances plus and minus is poor manufacturing, consistency shows tight manufacturing and good flight test and lots of plus shows generally conservative flight test.

[rickseeman]

I log all the numbers on every flight. (But the book is in the airplane so I can't be exact.) I don't have TKS. I am clean and waxed, top and bottom. I have the 3-blade but not the "fast" 3 blade of the Acclaim. I am usually light. I fly high, 10-12,000. My reason for this is because Mike Busch says if you fly where you can't make 65% power, you can't hurt the engine. I get 180 kts if I let it have some fuel. Around 15 gallons. But normally I burn around 13 and always get 175. Lately I've been running 2300. It costs me 4-5 knots, but saves 1 gallon per hour and is quieter. But always get 170. Cylinder temps 350, oil temp 190. Enjoy your O.

[RoundTwo]

13 hours ago, PT20J said:

A trick Don Maxwell does if the flaps still rub when adjusted to spec is to put the flaps down slightly to open the gap and then place a thin piece of wood on the flap nose and insert a stiff putty knife between the wood and the wing skin and gently flex the wing skin upward working slowly along the entire length of the flap The skins are thicker near the root so it takes more flexing, and the skins will spring back quite a bit, so it takes some experimenting. Just go slowly. It doesn't take much of a gap to clear the rivets.

I’ll look into taking it over to Joe Cole to check rigging and go from there.

Thanks

[Schllc]

10 minutes ago, RoundTwo said:

I’ll look into taking it over to Joe Cole to check rigging and go from there.

Thanks

+1,000 for Joe Cole. About one of the nicest guys you will ever meet.  Good communication, and reasonable rates. 

[RoundTwo]

37 minutes ago, Schllc said:

+1,000 for Joe Cole. About one of the nicest guys you will ever meet.  Good communication, and reasonable rates. 

Agreed

[M20F]

On 7/15/2023 at 1:57 PM, Ed de C. said:

Indeed, this is a Maintained-by-Clarence aircraft

The plane flies in metric then which is much slower then imperial.  I always recommend an imperial plane, they go the distance. 

[cliffy]

Where is your CG when in flight?  It makes a difference of a couple kts in TAS shown (trim drag)

[exM20K]

Your observed speed shortfall sounds about right to me.  Does the Ovation POH have this note which is in the Acclaim’s?

 

[rickseeman]

Mine is always forward.

[A64Pilot]

I have never seen any airplane of any make meet “book” speeds. My 201 for example isn’t a 201. But as has been said some are faster than others, and you will never figure out why, I never have. I searched hard because if I figured it out then I could make them all faster 

Be careful tweaking up the flap bay trailing edge, we had the exact issue with the Thrush, if your not careful you can crease the metal in the bay, best leave it to someone who can fix it if they crease it. Or drop the flaps just a smidge. On the Thrush we had an advanced special tool for setting the flaps, called a straight edge, we just made the flaps even with the bottom of the wing, make sure they are exactly the same though or you can induce a slight roll that changes flaps up or down, again probably best left to someone with experience.

Most people on these forums when quoting their airplanes speeds must use IAS, the I being Internet Airspeeds, or every airplane I’ve had was a dog, maybe it’s me that makes them slower than the forum ones?