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The bad gear was all celeron (or phenolic) including the teeth... which was what didn't last.  The 'new' gear has an aluminum rim & teeth on a 'celeron' hub.   Franklin Service Bulletin # 17  Feb. 13, 1942  addressed this and said replace them at overhaul (500hrs.)

The rate of wear (failure?) apparently was higher then they thought and with S.B. #21 of Dec. 7, 1942 (1 yr. after Pearl Harbor) they said pull any accessory and replace immediately if not previously done. 

If you have a 4AC-199 S/N 200533 or higher they came with the new gear.  If you have a 4AC-176 S/N 125270 or higher - same thing.

Old gear P/N not given - new gear  P/N 10725   (cost at that time was $6.00 !! )

Brett & Bill,

Post corrected 4/2012... after more thimking!

As a check to your posts above; (and brushing off my trig functions calculator) I looked at Bill's LCA engine mount drawing to see that the firewall is dimensioned to have a 20 degree slant.   Also, the vertical distance between the firewall mount bolts is 15.00".  That would be from center of upper longeron  to center of lower , since the steel brackets inside are the same (2 LH and 2 RH).  The 15.00" vertical and the 15.963" hypotenuse give a base of 5.460" or 5 15/32".

The difference between 11/16" (Bret's post above) and 15/32" is 0.119" or about 1" vertical error at the elevator. 

A 1 inch change at the elevator is about 0.38 degrees..... basicly very good !!

Attached is a drawing that should provide a clear picture.

Good post Brett,  I agree with what you have said.  I believe I recall that the CAR 4a required a loading of 4.2 G but will have to find it again to be sure.  The inboard lower aluminum bushing of the landing gear attachment cuts into the lower spar cap and creates "THE" high stress point.  If the gear attach fitting is not removed this area can not be inspected.  Because of the work to remove the fitting it is difficult to inspect. 

It is reasuring to remember that the fatigue life of wood is so high that it has never been precicely established!  These wings should last longer then all of us if they only had to stand up to normal fiying!  Its moisture and over stressing that gets them.

In two years when I move to NM full time (where my hanger is)  I plan to build some spars.  I have several as patterns and I have a jig (for routing out) that I think was used by one of the factories for forming the top & bottom faces.  I plan to try a "D" shaped aluminum bushing (withe flat of the "D" down) to reduce or eliminate the cutting into the lower cap as much as possible.  A "D" shape will carry the same vertical load but the side loading (into the end grain) will need to be investigated.   

It is interesting to note that in ANC-18 (Design of Wood Aircraft Structures, 1944) on page 235 &236 the Cadet spar was the subject of at least 5 test loadings to failure with modifications between each.  The production spar, it appears, was loaded to failure at a moment of 174138 in. lbs. on the fuselage (outboard) attach bolt.  I calculate that the 1/2 spanwise center of lift is very close to the inboard aileron hinge.  Using that (48" out from the attach bolt) and estimating the weight of one wing to be 100 lbs...(sombody put one on a scale and report back...!)  gives a design load of 4.37 Gs and an ultimate (fail) load of 6.56 Gs which is VERY close to the current utility catigory.

The indication from these same tests is that without the stress point at the gear attach bushing the design load would increase to 5.7 Gs.

Joe,

The mechanical advantage is not a problem but what you describe causes me concern.

I recomend strongly that you find and fix what ever is causing the lever to drag or not move freely.  A correctly rigged and un-dammaged gear lever SHOULD MOVE AS "SMOOTH AS SILK".  If it is hard to move this indicates either mis-rigged or damaged!!!

The one exception is that you should relieve the "UP" pressure on the ratchet (by pulling on the wheel) in order to move the lever fron RAISE to LOWER.  This is a two handed operation (therefore- trim it up and/or hold the stick with your knees).  Then keep your right hand sliding/gripping the wheel to slow the "fall" of the gear as it extends.

Sometimes (in the air) a little down pressure on the wheel is needed to hold the gears aginst the stop in order to slide the pins in freely.  This seems to vary with individual airplanes.  Gear fairings (or 500 x 5 wheels) may cause an air load that stops the gear before it reaches the down stop.

If it is difficult or drags moving into the lock position that is most critical and indicates that the down stop is not rigged correctly or that the two gear are not in 'sync' and do not arrive at the exact down position together. 

 Put it up on jacks and see if it is as hard to move on the ground as it is in the air.  If  all the above does not help and it is it is hard to move on the jacks ... fix it before flying again!  Far too many Culvers have been on ther bellys!  Review my rigging post.

One comment on my experiences with the slots...

If you are doing repairs on your slots, work hard to get then the same LH and RH.  I flew an airplane that came out of rebuild that had a measurable difference in the slot size.  If you were not looking for it you would miss it but because of it's handling in flight I got out a tape and started comparing LH & RH.  The slots were 1/4" to 1/2" more open on one side (variable spanwise).  Result?  Real wing heavy on that side!  Didn't fly it enough to install an aileron tab but I am not sure a normal sized tab would have been enough to correct it. 

So, what did I learn from that regarding performance and / or drag??  Learned this -  it does make a difference.  More slot = less lift = higher AOA required = more drag.   Is it measurable in day to day flying or when comparing airplane "A" to airplane "B"?  Probably not unless we take REAL carefull measurments and get kinda scientific about it!!

Neal,  To the best of my knowledge Culver never produced any detailed maintenance instructions other then the 5-6 pages in the back of the parts book and the Service Memos. Neither gives information on rigging the gear retract system. 

Here is my procedure for what it's worth... (this assumes that everything is assembled and not too far from correct function).  Maybe others will add their ideas below:

1) Take time to get a good secure method of lifting and supporting the airplane even when you are climbing in and out of it.  Also take time to read and understand Service Memorandum #1 - Care and Operation of Retracting L.G.
2) Make completely sure that there is NO EXISTING DAMAGE to the system.  No bent push rods, no bent or partly sheared bolts and everything secured correctly.  It is not possible to get the rigging right if any of the pushrods have been bent in service.  NOTE: Both main gear push tubes were made with slight bends to clear other things in the wings.
3)  With the gears 1/2 way up and the lever in the "RAISE" position insure that the locking pins are just clear of (but very close to) the 'half moon' plates that move with the gear.  See my gear pin drawing to understand why.
4)Disconnect the LH gear (both push rod and locking pin rod) and block it in the down position for now.  Rig the RH gear in the up position such that with the ratchet's last click, it is within 1" of as far as it can go up.  Adjust the outer link in 1/2 turns to do this.
5) Lower the gear and adjust the 'down stop' screw (lower LH end of the rack & gear box) so the lock pin locks the RH gear. The pin movement into the gear should be 'smooth as silk'.
6) With the RH gear locked down rig the LH outer link in 1/2 turns until that lock pin also slides in 'smooth as silk'.
7) Re-connect everything and retract the gear.  If it is possible to retract the RH gear back to the same 'ratchet's last click' and the LH gear is not hanging out of the well... be happy, that is about as good as you can do.
If the LH gear is ahead of the RH and prevents getting back to that 'ratchet's last click' you will have to start over and rig the RH gear a little lower, say 2 inches from hitting. 

One gear seems to always lead the other into the wheel well.  This is in part because one gear 'rack' is above and one is below the center gear so the gears are 'pushed' from different points.  It is real hard to get them fully retracted, together. 

From a safety standpoint it is most important that the lock pins move into the lock position as smoothly as possible and as completely as possible AND do it only when aginst the down stop screw.  This is the "standard" by which you must judge the 'health' of your system as time goes on so get a feel for it now and remember what it's suposed to work like.  If some day it does not work as well that is your "red flag" to fix before further flight or fly gear down only... until you can.

Bill,
I have a drawing for a home-made stinger tail cone in an older Cadet news letter.  Will try to scan and post it. 

I have looked a lot but have not seen "THE MARK"!

A few of us have come up with alternate methods of leveling (usually easier).  Next person that has a reason to level your airplane try all 3 and report back!

1)  The door sill should be 2 degrees nose down when the airplane is level.  2 Degrees is equal to a 5/8" block at the end of an 18" straight edge.  Masking-tape a small block of wood 5/8" thick 18" from the end of your level.  Set the level on the door sill (block FWD) and that should read level.

2)  Place a block of wood on the top of the spar inside the cabin to raise the level above the steel tubing and that should be level too.

3) (Added 2/2)   On a review of the LAR-90 TC sheet, it states that the LAR-90 is basicly the same as the PQ-8 which we know to be basicly the same as the LCA / LFA except for the gear.  The Leveling means for the LAR-90 is to remove the wing-fuselage fairing and place a level (vertically) aginst the front face of the spar.  This is effectively the same as #2 above.