A

avi8tor50

Well Known Member
Hi all-

Getting ready to install the oil door. I would really like to use hidden hinges and the "push button" latch that some have used. I know about the McMaster Carr hinges and the Guden hinges (they have $25 minimum order plus shipping). Was wondering if those of you that have used the McMaster hinges had any difficulty getting them to work (I'm building a 9A).
Also, the recess that is molded into the cowl does NOT allow the door to fit flush with the cowl. What have others done to make this fit better?
Finally, where can you get the "push button" door latch?

Thanks all!
Peter K
9A
 
avi8tor50 said:
Finally, where can you get the "push button" door latch?
Click to expand...

The "push button" latch can be purchased from B&B Aircraft Supplies at 913-884-5930. The latch model # is KM610-64. When I bought mine a few months ago they were $5.00 each, and B&B had a $10 order minimum. Buy two and sell one of them to a friend. That's what I did.
 
I bought a McMaster Carr hinge but found it was very heavy. I try to make my own but finally bought the one from nonstopaviation.com. It has a spring in it which keeps the door open. cost is $39.95. They also carry the button. I bought my button from B&B for less.
 
Oil door notes

My door fits in the cowl recess after I narrowed it along the 4 sides. The door gets progressively thicker toward the aft edge so the top aft surface sits above the surrounding cowl. Must've been laid up on a Monday. I did rivet a fluted length of angle on the underside near the forward edge to keep the door from flexing and opening in flight. An aluminum door is on the "winter project list".
I used the push button latch from the surplus store in Kansas. Another builder on this site has the address.
I used 2 Mcmaster-Carr hinges. The door opens slightly less than 90 degrees because the top edge of the door contacts the top cowl when its fully open. It's the price you pay to have hidden hinges.

Steve
 
To solve the issue with the fact that they do not mold in square corners on the recess, I cut the door slightly smaller than the flat part of the recess.

I then installed the door, covered the edges with packing tape and closed the door and latched it. Once this was done I used SuperFill to fill the gap all around the door and feathered it out onto the cowl nicely.

Rough up the glass and ensure it is super clean before adding the filler.

After it cured, sand down with a block, feather it out, and take fine grit paper to the edges to round them over.

Turned out great.

DSCN6953.jpg


DSCN6955.jpg


PS. I can't afford a fancy hidden hinge and pushbutton latches (trying to save for avionics!) so I went with the plans, inexpensive, works great and really does not look that bad!
 
bullojm1 said:
Peter-

I made a metal oil door and used a Sam James cowl, so I don't know how much of my documentation applies to you, but here it is:

http://rvplane.com/?categoryid=6&dayid=647


No problems installing the push-button latch. It works great!
Click to expand...
Mike-Did you use an alumininum doubler on the inside of your cowling to serve as a "strike-plate" for the latch? (It looks like it.)

On my installation I found that the latch just barely has enough fiberglass to grip once I filed the opening large enough to allow the door to close. It takes quite a bit of force to open the door without pushing the button, but I'm wondering if my latch will get looser over time as the edge on the cowl opening gets worn. I don' want the door popping open in flight!
 
alpinelakespilot2000 said:
Mike-Did you use an alumininum doubler on the inside of your cowling to serve as a "strike-plate" for the latch? (It looks like it.)

On my installation I found that the latch just barely has enough fiberglass to grip once I filed the opening large enough to allow the door to close. It takes quite a bit of force to open the door without pushing the button, but I'm wondering if my latch will get looser over time as the edge on the cowl opening gets worn. I don' want the door popping open in flight!
Click to expand...


Yeah, I made a doubler out of some 032. I plan on putting a piece of tapered 063 behind the 032 where the latch comes in contact with the doubler to reinforce it even more.
 
Made my own hidden hinge

I made my own hidden hinge out of 032. Took 1/2 an hour and works great. Not spring loaded but I saved time and shipping to the UK.
I then did exactly the same as Brantel and glassed up to the door edges.
I also got rid of the butterfly's on the standard catches. The only downside I need a screwdriver to open the door but it looks much better.

Peter
 
Unless someone can prove otherwise with information that predates my own, I lay claim to being the first RV builder to install the KM610-64 flush latch. An archive search on another RV forum will support the claim as I described the discovery while seeking a novel way to secure the oil door (the RV-7 hadn't been invented yet) after reviewing countless RV's at 2 consecutive AirVentures. I was finally inspired while observing a student preflight a Cessna 172. What followed was the subsequent and expensive part purchase at the local FBO, and the later experience of finding the exact latch at a vendor at the Flymart selling it as "new surplus" for a mere fraction of what I paid. Years later, the latches still work just fine and for me at least, no more pleasing to-the-eye oil access door fastening system is out there. As the second photo shows, the door is reinforced with the waste material that was cut away to make room for the door. Since the grip reach is limited with this latch, care must be taken to insure the cowl lip is reinforced to give it something to grab onto other than just raw fiberglass.

 
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If someone wants to order a couple of these, I will take one and gladly pay the extra shipping. Perhaps B&B can split the order and ship part to you and part to me? If interested, send me a PM.
 
Rick-

Was wondering why you chose to place TWO latches. For you and others who have used these latches, is one not adequate to hold the door closed?

Peter K
9A
 
avi8tor50 said:
Rick-

Was wondering why you chose to place TWO latches. For you and others who have used these latches, is one not adequate to hold the door closed?

Peter K
9A
Click to expand...
Pete,

I have read more than one account of the oil door popping open in flight when the builder installed only one (non standard) latch. There is considerable outward pressure on that door at flight speeds. The KM610-64 was designed for aluminum structure and the latch itself has relatively little grip. Works fine on aluminum structure such as the Cessna 172 oil door, but our RV's are MUCH faster and it must remain secure gripping a fiberglass cowl. I kept that in mind when I decided to go ahead and use the latch anyway. Note that per plans, Van's would have the builder install two kit supplied latches and I accept that as a cautionary note.
 
Rick6a said:
Pete,

There is considerable outward pressure on that door at flight speeds.
Click to expand...
I can second that. I have considerable time in the Cirrus SR22 which has a two latch composite oil door that latches on the opposite side of the hinge like the Vans design. At cruise speeds the door itself bows upward quite a bit from all the internal pressure in the cowl. They don't seem to fail generally, but I know a guy that one of the latches did fail and the second held firm, so its prudent to have more than one.

The cruise speeds and the construction methods for the door are similar on a 7 as the Cirrus 22 (sorry, but true :p ) - albeit on a lot less fuel. The newer design rounded the access side and put the latches at 10 and 8 looking forward (hinge on the 3 o'clock).

Based on that when I get to that point on my 7A I intend to make it pretty robust.
 
I've found that with an aluminum strikeplate and careful adjustment, the single latch will provide enough force to keep the door closed in flight.

If you have any doubt or want redundancy, two latches are fine, but I highly recommend using an aluminum strike plate that is removable/adjustable to ensure maximum security.

Vern
 
oil door

A single latch works fine if you stiffen the oil door by adding a couple ridges to the inside of the door. A small piece of cord with a couple layers of glass over it add alot of stiffness to the door. I put two ridges on the inside of my oil door, one on each side of the latch, and after 462 hours of flying, it is still on.
 
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