Cowling / Prop Question

[greggrv7a]

Wondering if anyone with a three bladed prop can help with a problem I am having with installing my bottom cowling on my 7A. I would appreciate any help / pictures from anyone who has had the same problem.

Tnxs,

Gregg

 

[db1yg]

Gregg,

I have a 3 blade Catto on my RV9a. To mount the bottom cowl the slot in the cowl for the nose gear has to be cut forward more than the two blade equiped RV. Cut a little at a time to insure you get just the minimum amount with some additional for gear flex. Note that the cowl is best mounted at a slight angle with one side lower than the other until the blades are cleared--then straight on. Two people are required--especially when initially fitting. Put some tape on the edges of the prop to avoid scratches from the hinges between top and bottom cowl (the horizontal hinge) as it passes by the blades. To cover and reinforce the lower cowl I extended forward my nose gear leg to cowl fairing by about 6 inches. I have some pics somewhere--let me know if you need them.

Hope this helps!!

Cheers,

db

 

[steveciha]

I remember when i started to fit my 3 blade whirlwind prop. I thought,"this is never going to work" but it will. just cut the slot longer. There is a definite install, remove scheme that you will find works for you to get the cowl off and on. After a short time i caught on to doing it myself with no problem. I did make a nice fiberglass fairing to cover the long nose gear slot in the cowl. It helps to stiffen up the bottom cowl in the nose gear area. I can take a picture for you if you like. It will be a little while though.

steve ciha

 

[pierre smith]

Funny you should ask.....

Hi Gregg,
We had the same issue with ours but we have the fairings-etc upper intersection fairing and it's really long with one nut plate/screw at the very front end. I finally had to cut the slot as near the nutplate as I dared. We still have remove that intersection fairing to allow the bottom cowl to drop as far down as possible and with a helper, raise the rear as high as practical while you slide it carefully forward. It's tricky but it can be done without scratching the prop if you duct-tape the prop first.

Regards,

 

[jimski9]

Pierre or Dave

I have a Catto three-blade prop and have cut a longer slot in my 7A lower cowl. However I don't think it is long enough yet.
Can you, or someone else with this set-up measure how long a slot you made to allow easy removal of the lower cowl?

Thanks

Jim Talbot
7A
New Zealand

 

[db1yg]

Hi Jim,

I will be out at the hangar later today and will measure the distance from the nose gear leg to the forward most point on the slot--is that what you need??

Cheers,

db

 

[db1yg]

Jim,

Just got back from the hangar. It looks like mine is between 7.5 and 8.0 inches from the front of the gear leg where it exits the bottom of the cowl to the forward most part of the slot. I have the FairingsEtc intersection fairing that I cut and glassed so it extends forward sufficient to cover the extended slot.

Please note that I have the James cowl which is slightly longer than Vans stock unit--don't think this would matter but .....??? I arrived at this dimension by cutting forward a little at a time until I was satisfied that I had the shortest slot that allowed bottom cowl removal.

Regardless, as has been mentioned, you need to protect the 3 blade composite prop when you remove the bottom cowl.

Hope this helps!

Cheers,

db

 

[jimski9]

Thanks Dave

I will lengthen the slot in my cowl some more.
I think the most important thing Pierre and you have said is to duct-tape the prop before fitting or removing the lower cowl.
I would hate to scratch my new prop before I have even flown!

Cheers

Jim

 

[RickWoodall]

cowl fitting tips for 3 blade install

I read in the archives that the rvator had an article on cowl fitting tips for three blade installs. Cant find it after much digging. Anyone recall how long ago, date of that article etc?