Cowling and spinner interference

[inflight]

I assume this is due to the new engine mount bushings. I don't recall where it was when I first bought the plane and I have had all the cowling off since then. Any ideas on a fix? I haven't run the motor yet since replacing the bushings so maybe it will "settle in" a little. Also, why do my pictures all come up sideways and how do I fix that? Thanks.

[jiott]

The simplest fix would be to install washers under the bolt heads where the engine mount attaches to the firewall. The shim washers under the top bolts would tip the whole engine assembly down and forward, which is what you want to line up with your cowl. The down side of this, of course, is that you will have changed the whole thrust line of the engine, which will affect the flight characteristics to some extent. How much I don't know. Maybe you will get lucky and it won't require enough shimming to matter much.

The other fix is a more laborious rework of the cowl where it attaches to the firewall to pull it up and back.

A longer prop spacer would get you clearance, but the lineup with the cowl would still be ugly.

[rosslr]

HI Mark,

I am no expert but something doesn't seem right here to me! I mean the cowls would have fit ok originally when the engine was first fitted and the bushings were new would they not? Others more knowledgeable might be able to suggest possible reasons but the only thing I can think of is that the original bushing may have been different to ones you have used????? I guess I would just want to understand why the new bushings have raised the engine to the point of interfering with the cowl rather than restoring it an even distance all round? Does the old owner have some pics of the gap you can compare?

I am sure you will get some good advice here but looks like you are making good progress with your overhaul - wont be long now!

cheers

ross

[jiott]

Good call Ross. That is hard to explain. Some investigation is in order.

[inflight]

The motor and mount came from another airplane originally and had around 100 hours before being installed on this plane. That is why I was thinking there may have been a bit of sag before the cowling was originally fitted for this airplane.

[Dave S]

Mark,

When you got the plane originally....was the cowl in place and correctly aligned?

Reflecting off Ross's comments...if cowl/spinner was correct originally, a person would think it should be the same with new bushings.

I see you have one photo of the ring mount, firewall mount and the bushings that were in place from your 7/12/2016 post.....in comparing that photo to the current asssembly of the mount - can you observe any differences in front/back offset between the top and bottom rubber bushings? The rubber bushings from the 7/12/2016 photo appear to centered correctly??

I am sure you will figure this out...and it is an interesting predicament.

[inflight]

I have definitely learned that you can't have too many photos. You would think I would know that already. Here is a shot from before the cowl ever came off the first day we saw it.

It looks like it may have had some clearance issues from the beginning but it is hard to tell from this photo. You can see some of the darker blue from the spinner on the cowl. But that may suggest some separation and only an occasional contact. I wish I had a better shot.

[Esser]

I know it's a long shot Mark but do any of the videos your wife took show a side shot? Probably from too far away if it does....

It will be MUCH easier to try to get this thing to settle down instead of reworking the cowl.

In fact, I would shim before I messed with the cowl. Sure your thrust line may slllliightly change but it would be to where it was before you did the swap.

[Dave S]

Mark,

You know, with all the photos I took of our kitfox.......after the fact I found that I could have taken more:o...I think that is a common thread. I know what you mean.

After looking at the photo in your last post, I think it is pretty clear that the original clearance between the cowl and the spinner is less than it should be...although that doesn't solve the original question. I'd guess that the paint transfer could have occurred from the simple act of removing and replacing the upper cowl. Some photos attached of the cowl fit on our plane - although it is an S7 and not the same exact cowl - but you get the idea.

I wouldn't want to speculate too far out as to what the case may be; but, there are likely only a limited number of possibilities.

1) The bolt up of the new bushings may have ended up differently between the old and new bushings - finding some way to make that comparison would be a good start.

2) The order of assembly when building the firewall forward should be in your build manual - basically the engine and engine mount is assembled first, then the cowl is adjusted to match the prop hub, camlocks installed and spinner fit. I wouldn't rule out the possibility that there may be multiple things adding up affecting what you see - a little from the bushings, a little from the cowl fit, oversize camlock holes(?) etc....but I am speculating a lot - studying the build manual might help figure this out.

3) If the engine mount came from a different aircraft....might be good to check for any damage/bending to the mount, unless it is known be correct. Wondering if this was the only/first engine mount fit to this aircraft; or, is it one that was install later when a different one was installed first?

In any case, well worth taking your time to figure it out before drastically modifying anything.

Hang in there - we all have our challenges.

[inflight]

I know it's a long shot Mark but do any of the videos your wife took show a side shot? Probably from too far away if it does....



Unfortunately I never put the cowl back on after we took it off the first time we saw the aircraft. So all the videos are cowl off.



It will be MUCH easier to try to get this thing to settle down instead of reworking the cowl.

In fact, I would shim before I messed with the cowl. Sure your thrust line may slllliightly change but it would be to where it was before you did the swap.

I am wondering if I overtightened the bushings or forgot some washer shims in between the firewall and the motor mount. I'll look into that first. Like you said it would only put the thrust line back where it was.

The motor came off of one of Murle Williams airplanes and I have confirmed with John McBean that it is actually a series V round cowl firewall forward which was reworked for the series 6 smooth cowl so I am dealing with a bit of a custom job. I guess all kit airplanes are custom jobs.

My build manual doesn't have the firewall forward part of it because, I'm assuming, that the builder didn't buy the firewall forward from Kitfox. I would love to have that part of it, although with it being so custom, I'm not sure how much it would help. I'm sure there is good info in there that I don't have however, like how much to torque the bushing part of the mount.

And on that note, the bushings I got are exactly the same Lorde model number so unless they changed something, they should be the same.

Thanks for the ideas and support. The community here is fantastic!

[inflight]

Dave that is a great looking cowl setup. It is amazing after staring at this airplane how I am still finding little things I might have done differently.

I inspected the mount thoroughly while it was removed and didn't notice any bent or damaged pieces, but I am certainly no expert.

Thanks for the encouragement. For as long as it is taking to get an already built airplane back in the air I have a new found respect for those of you building from scratch. I'm getting antsy to fly. As someone here put it, I think, I'm getting the ground sickness.

[rosslr]

Your right about this forum Mark! There are a lot of wise heads here! I followed your thoughts in the threads and I think you asking all the right Qs and checking all the 'possibles'. My only advice is don't let the itch to go flying outweigh your peace of mind that you will get from understanding the logic that has lead to this situation. The only other question is did the plane actually fly with this engine and cowl configuration?? Are you able to chat to the previous owner about this? - they surely could shine some light on this.

Best wishes on getting satisfactory explanation on this!

cheers

r

[Mcslamma]

A simpler fix might be, after considering all the other ideas mentioned here and ensuring no deficiencies were present, would be to lose that spinner alltogether and install an IVO skullcap spinner that allows for quick access to prop mount bolts and inspection of tape etc.. and does not get anywhere near the cowl,

My model IV had a large spinner same as yours when I obtained the airplane, but I replaced it with the skullcap when I changed the original prop with IVO IFA, and I have come to really like the look of it, as it reminds me of the front of a DHC Beaver every time I look at it.

From your pic it looks like you have an IVO prop as well..

Good luck in your efforts...

[Av8r_Sed]

I second Craig's comment here. I cracked a blade at the root on my IVO medium due to the fiberglass backplate on the UHS spinner. The problem occurred because the fiberglass compresses after torquing the prop bolts and the blades then loosened. Removing and replacing all the spinner screws in order to follow the IVO torquing schedule is also a pain.

[Esser]

I have a the 914 FWF manual if you need any info off of it. I'll be home tomorrow aft so I can dig it up for you. But Beyond torque values, I'm not sure how much help it will be for you.

[kmach]

A IVO skull cap looks fine on a round cowl, a smooth cowl is best with a full spinner.
I think the problem needs to be fixed, not lived with it .

I'm thinking there were some washers between the mount and firewall that got missed on re install. It wouldn't take much to make a difference out by the spinner.

[Esser]

I wonder if a prop spacer an extra 1/2" might be an option too.

[inflight]

Esser- I would take some torque specs if you have time to look that up for me. I appreciate it.

I'm with kmach, and leaning towards some missed washers between the mount and firewall. I'm heading out to the airport to work on it soon. I'll keep you all posted on what I figure out.

I want the alignment to be where it should be but I'm also thinking I may sand the spinner and backing plate down a bit for more clearance.

[Av8r_Sed]

11578Looking at this again, I believe the spinner backplate is designed to go on the front, not behind the prop. I've seen them both ways, but mine was mounted on the front.

http://http://www.uhsspinners.com/installs.html

[inflight]

I missed the washers against the firewall. Once they were installed the alignment was much closer. Then I loosened the bushing bolts so that the large retaining washer was just in contact with the spacer but not snug. Those too things combined fixed my alignment problem. Thanks for the help guys!

[Dave S]

Hey Mark,

That's good news that you had an inexpensive, uncomplicated fix...In my alleged life as a mechanic, I have always found that when taking something apart, time is well spent if a person documents how things were before they came apart (which I have also found is not necessarily correct all the time), in writing or photographs (digital cameras are great).

Onward and upward!

[inflight]

I agree. I have taken a ton of photos but not of every detail apparently.

After reading Av8r_sed's post I am considering removing the spinner and backing plate altogether. I had not yet seen or read that having a composite backing plate within the prop installation could cause a loss of bolt torque. That's a scary possibility. Those with IVO props, what are you using for a spinner?

[inflight]

I actually just found some video I shot detailing the motor mount to firewall install before I removed it and I DON'T see washers between the mount and the firewall. I am wondering if there were washers behind the firewall in between it and the fuselage. Stupid memory. Anybody have any photos or manual info about installing the motor mount? I wish I had that part of the manual.

[kmach]

shimming the motor mount with washers is common.
I did an engine swap last year took over 100 picture of things like that.
I have been maintaining/ improving this KF for 6 years , so pretty used to where things are ,but, still do not remove anything without taking detailed pictures.

I have a 3 blade IVOPROP medium IFA with a fiberglass 9 or maybe 11" (for the IFA motor to fit) UHS spinner. The spinner backplate mounts the most forward or on the front. I used 2 Fender washer under each bolt head to help with backplate crush. I have had the prop off a few times. It does not loose its torque. I check the bolt torque at the recommended 10 HRS.
After the initial torque checks when you install , I have never had the prop bolts out of torque. 400 hrs with this setup.

Another key is to mark the prop blades with hub position , so the knurls go back in the same spot.

[Dave S]

After reading Av8r_sed's post I am considering removing the spinner and backing plate altogether. I had not yet seen or read that having a composite backing plate within the prop installation could cause a loss of bolt torque. That's a scary possibility........

Mark,

I think a lot of things can seem scary if a person is not familiar with them......On the composite/fiberglass spinner, we are running a UHS spinner with a composite bulkhead. The bulkhead has be on the front of the stack, not sandwiched in between spacers or the prop hub, according to instructions. Also, the assembly includes fender washers to go against the front of the bulkhead before the AN washers and bolts which spreads out the pressure. At least in the instructions I received with the spinner kit, as well as with the Warp Drive Prop there were notices to check the prop torque at regular intervals. What I discovered was a very minor tendency for one or two bolts to lose a small amount of torque at first, but that quit happening after a few hours. My opinion is if the directions are followed for the correct assembly and checking the torque - this will never be a problem. One thing to keep in mind on the composite bulkhead is the nuts imbedded in the fiberglass can be messed up if overtorqued - they are not like a regular nut but have thin walls so excess torque on the spinner screws can potentially spread the nut(s) to the point they will not hold. UHS recommends using blue locktite on these which works real well.

Want to hear scary?.....at an airport which will remain secret, I am aware of a "normally" certificated aircraft with an aluminum spinner on shut down - as the engine rolled to a stop, a noticable clatter came from the aluminum spinner. Apparently the spinner also can serve the purpose of storing prop bolts that have come loose for some reason or other - suspect that never would have been necessary if the thing had been assembled correctly in the firstplace....oh well.

[Dave S]

Kevin,

I like the Ivo prop install:)......it would be great to have an adjustable prop; however, that one got backburnered due to budget in my case...maybe some day.

Mark,

Forgot to mention; but Kevin's post reminded me, there was also a 1/4" steel crush plate which I believe came with my prop for use depending on what other stuff a person installed - photo attached. Ignore all the wires - that was a data logger testing the effectiveness of the Tanis heater (tends to get a little chilly up here in the winter) ;)

[inflight]

I think mine is definitely installed wrong. The backplate is between the hub and the other plates. Kmach, since I don't have any of the original instructions, could you give me a simple step by step to removing the prop? I have the same "through the hub" electric connection as you. Thanks.

[Esser]

http://i1042.photobucket.com/albums/b423/joshesser/Kitfox%20Build/B24322C8-FA30-44B0-81B1-BCDDA425DBC9_zpsm42hzuao.jpg (http://s1042.photobucket.com/user/joshesser/media/Kitfox%20Build/B24322C8-FA30-44B0-81B1-BCDDA425DBC9_zpsm42hzuao.jpg.html)

http://i1042.photobucket.com/albums/b423/joshesser/Kitfox%20Build/A765B0DB-9099-4EAD-A6C7-D1EF27CBDB58_zpslk9h2yry.jpg (http://s1042.photobucket.com/user/joshesser/media/Kitfox%20Build/A765B0DB-9099-4EAD-A6C7-D1EF27CBDB58_zpslk9h2yry.jpg.html)

http://i1042.photobucket.com/albums/b423/joshesser/Kitfox%20Build/1D0AD89F-5F19-4878-94E7-59F41A8C2C1B_zps6nsua3jz.jpg (http://s1042.photobucket.com/user/joshesser/media/Kitfox%20Build/1D0AD89F-5F19-4878-94E7-59F41A8C2C1B_zps6nsua3jz.jpg.html)

http://i1042.photobucket.com/albums/b423/joshesser/Kitfox%20Build/AB11DFBE-2ACF-41BC-A603-E944ECD318AB_zpsrkw6y48t.jpg (http://s1042.photobucket.com/user/joshesser/media/Kitfox%20Build/AB11DFBE-2ACF-41BC-A603-E944ECD318AB_zpsrkw6y48t.jpg.html)