What’s the latest on 1340 overhauls? I heard a rumor that Covington was out of the business but their website says otherwise. What other options? Tulsa? Anything else? Do any offer exchanges? Thanks!

Avoid at all costs any radial with components balance by Barrett.

I have a R-985 down at Younkins now getting the crank rebalanced. They said that last year they rebalanced 10 or more that were 100 grams out and one 1340 was 200 grams out. All balanced by Barrett.

It got so bad they tried to give Barrett the formula so they could get it right but they still do it some other way and it's causing a lot of issues.

2nd order vibrations (2 per revolution) so a dynamic propeller balance will NOT fix the problem.
The balancer may find a solution but it does not fix the vibration and in some cases makes it worse.

This has been an issue for 15 or more years and it really should be stopped. If you wonder why some run smooth and others in the same airframe type vibrate the pitot tubes and stick all the time this is it. It has caused me hours and hours of trouble shooting and attempts at fixes. Pulling the engine 3 times to send back Tulsa. Pulling cylinders to try different pistons, wrist pins etc. Changing all accessories, changing engine mounts. Multiple propellers 2 and 3 blade.

It's been a nightmare.

Where did you hear that rumor? New owner of T-6 here very interested..

Did you mean R-1340?

Did you mean R-1340?

Yes, got dislexic there!

Heard great things about Younkin, however they say currently 18 month lead time for overhaul. Either need to send them a core or $12k to hold a spot for that.

Last I heard an R-985 was easier to keep flying than a GO-480 from a parts and support perspective. Not sure if that's still true (or ever true). I used to own a T-Bone but have never owned a radial....but would love to have something with a Wasp someday.

Is there any difficulty keeping these flying? I wonder what's driving the long lead time at Younkin.

Covington is phasing out their radial business by next year I heard. They want to concentrate on their turbine business.

Covington uses a balancing procedure produced by Air Tractor. I was told it only a single plane balancing procedure.

Monty Barrett developed the balancing program for Tulsa Aircraft Engines in the late 1980's. Monty passed some years ago. His sons are not part of the business anymore.

Dynamic prop balancing radials can be tricky. I find it imperative to use two channels.

Younkin Engines was started by Bob Younkin. His brother was Jim Younkin, inventor of the Century series A/P and later Tru-Trak autopilots. Jim's son was Bobby who was the airshow pilot.

Modern Pratt -985s and -1340s are the -360 and -540 of the radial engine world. They are essentially bullet proof and well supported.

40 years ago when I was a freight dog, there were shops doing "paint job" overhauls and that is what the guy I flew for bought. They were grenades with the pin pulled.

I've heard that Sun Air Parts is buying the Radial Engine Business from Covington.
The owner previously bought much of the Inventory when a shop closed in Southern Calif.
The new shop will be near, or on, Flabob Airport.
Sounds good as far as rumors go. Hope it happens.

I was told today, Covington quits Radials overhauls December 31, 2025. They will maintain a capability for warranties.

Yeah I sent a request to Covington this week and they came back and said no more radials.

It's happening. I visited with Nando Mendoza at West Coast Air Creations at Flabob a couple of weeks ago. He's building a new hangar for the engine shop and will be doing 985 and 1340 overhauls there. He's hired very experienced people, bought the tooling and will be doing OH's beginning in June-July IIRC. Nando is a terrific young man and very talented. I have no doubt they will do excellent work. If I was overhauling one of those motors that's where I would go.

Yes my engine was done by Sam at Tulsa just about the time they were changing and Rex took over. It was built from "new" components. About 70+K for the overhaul.

I sent it back 3 times to Tulsa and then flew it to Covington and we pulled a cylinder to verify counterweights. Covington tried to prop balance but it was worse. Balancer came up with a solution down to .02 but it would about shake your hands off the yoke in flight. I removed the weights.

I flew it to Hartzell in Ohio and met with Les Doud. (Hartzell engineer) We mounted the velocimeters on the nose, accessory case, and pilots seat base. Flew at different RPMs , takeoff, landing climb etc to map it out. Balancers Recording the vibrations on the ground and in the air.
I tried 5 different balance people and finally bought my own balancer to try and find the issue. Still no luck. Hard VIP mounts, soft mounts, flying with no baffles or cowl etc. Moving the velocimeter on the nose to different clock angles and lined up with the master rod or 90 degrees off from it. Different blower, different alternator drives, no alternator, different carbs, different props, governors, mags, plugs, valve clearances, etc. Greg at Younkins was the first to understand what I was dealing with. Rex at Tulsa kept saying my Ailerons were out of balance... We mapped it out at Hartzell and there are different vibration peaks but mainly at 2X crank RPM. I'm running a 3 blade Beaver Hartzell.

We have another 985 here on a Bellanca CH400 Skyrocket overhauled about the same time with the same vibration problem. Jim Jeffries came and tried to balance it but it still shakes. 2 blade Ham Standard.

I suspect this vibration is also what Delmar experienced when the Gee Bee R-2 engine was overhauled and he lost confidence in the engine. Similar time frame for the overhauls on all.

all Tulsa engines balance by Barrett.

To compare the old Leech engines on the Skydiver E-18 I was flying ran smooth. I used to be DOM for a 135 with four wheel equipped Beavers in AK and the R-1340 in the N3N I was flying were all smoother. Current Younkin engine and old Aerorecip in the Beaver I am flying now are smooth also. It's hard to explain but you can see it in the Pitot Tube, instruments and feel it in the floorboards/yoke. Better at takeoff RPM and worse as you bring the prop back.

I don't know the differences in how the cranks are setup but it is something with the formula for the counterweights and other differences. Like Barrett was balancing the supercharger impellers spinning in open air with air hose where Younkin has a sealed box to spin them in. Our vibration is not 10X crank RPM but it's procedures differences.

The R-680 in our other Stinson with no dynamic counterweights runs smooth. No special prop balancing at all on any of the others. The airframe is not a natural shaker from airflow or flexible structure.

Big test will be when I get the engine back and install it. If it runs smooth then I know what the problem was for sure. If not then I'm into the engineering and approvals for changing the engine mount to use a Beaver mount ring and shock mounts as the next thing to try. They are a kind of dynafocal setup aimed towards the center of the engine.