Wing Washout/Dihedral on 1946 C-140

[8024]

Greetings all:

A friend of mine is working on a 46 model 140 project. He and I have been getting it ready to get back in the air. It was completely disassembled when he purchased it. My 1947 C-140 S/N 14025, has eyebolts for adjustment on both the front and rear spar attach points, however, the struts on this 46 model have a fixed attach point at the front spar attach point (only an AN bolt and no adjustment) and then the eyebolt adjustment at the rear. Even the early 100 series manual does not show the 140 adjustment but starts at the early 150 with the eccentric bushings at the wing root for adjustment rather than at the strut attach points. Does any one have the starting point (i.e. measurements and where to measure from, etc.?) to ensure the dihedral and washout is correct (or at least close) for initial flight testing and then how to adjust as required for a "heavy" wing? Please email: smokinrivetairparts@gmail.com if you can or reply here but might take me just a bit longer to check here. Thanks in advance!

N4112N
1947 C-140
S/N 14025

[6643]

CESSNA SERVICE LETTER SLN-49

Website->Resources->Service Letters

[V529]

Greetings all:

A friend of mine is working on a 46 model 140 project. He and I have been getting it ready to get back in the air. It was completely disassembled when he purchased it. My 1947 C-140 S/N 14025, has eyebolts for adjustment on both the front and rear spar attach points, however, the struts on this 46 model have a fixed attach point at the front spar attach point (only an AN bolt and no adjustment) and then the eyebolt adjustment at the rear. Even the early 100 series manual does not show the 140 adjustment but starts at the early 150 with the eccentric bushings at the wing root for adjustment rather than at the strut attach points. Does any one have the starting point (i.e. measurements and where to measure from, etc.?) to ensure the dihedral and washout is correct (or at least close) for initial flight testing and then how to adjust as required for a "heavy" wing? Please email: smokinrivetairparts@gmail.com if you can or reply here but might take me just a bit longer to check here. Thanks in advance!

N4112N
1947 C-140
S/N 14025

I'm not sure if you're asking whether the fixed front strut is an issue or not, so I'll respond this way. Starting later than your 47, probably almost into 1948, Cessna "made some cost cuts" and having a strut on the right side with the forward end fixed became standard practice. You don't see that many of them. Why you have a 1948 strut (strut set?) on a 1946, only means the original set of struts to your 46 got lost somewhere over the preceding 72 years.

[simpsone]

S.L.N.-49 tells us and our A&P exactly what to do, namely lengthen the rear strut on the LIGHT wing. The joy this purest form of Cessna Poetry brings to me is indescribable. Nevertheless, I am left with the nagging question-Which is the LIGHT wing? Please, fellow Pilots with more experience and insight, help me to understand. Holding the Right Rudder is not the way I want to cruise. A gentle little left bend added to the Trim Tab lessened the Rudder work, but exposes the LIGHT wing. Is it the up one or the down one? LIGHT in this example of Cessna's finest SLNese doesn't make it for me. If both Right and Left rear struts are made very nearly 109 13/16" (C/L bolt hole to C/L bolt hole) as the same SLN says they should measure, will that nearly eliminate the LIGHTness?

Thanks for your Consideration.

[6643]

The light wing is the one that wants to go up and the heavy wing is the one that wants to go down. If the plane tries to roll right the left wing is the light wing, and vice-versa.

[simpsone]

That makes sense. Thanks, Mister Cooper.

[7698]

The light wing is the one that wants to go up and the heavy wing is the one that wants to go down. If the plane tries to roll right the left wing is the light wing, and vice-versa.

When making the adjustments to the light wing... Generally, how many turns would you wind the thread out at first? What I'm trying to ask is if small adjustments , say 1/2 turn, have a big effect?

[6298]

A half turn may be all it will take. Start with that and see if it makes a difference. Easy to keep trying with half turn adjustments.