tapping brakes wih rudder pedal applicaion

Ask Questions and Offer Advice Related to the Cessna 120 & 140 Type
Forum rules
You must be a member of the Cessna 120-140 Association in order to post new topics, reply to existing topics, or search for information on this forum. Use the "Join" link in the red menu bar.
Post Reply
fbh140
Posts: 5
Joined: Sat May 04, 2024 9:20 pm
Name: Frank Huber
Location: KANE
Aircraft Type: 1948 C-140
Occupation-Interests: Retired pilot NWA/Delta
Contact:

tapping brakes wih rudder pedal applicaion

Post by fbh140 »

I recently purchased a 1948 Cessna 140 and am having issues with the brakes being applied when I move the rudder pedals, both taxing and takeoffs and landings. I owned a 1946 Cessna 140 back in 1984 through 1989 and never had this issue. I have big feet but have been making the point to only moving the rudder pedals with this tips of my toes. Looking at the Cessna 140 parts manual, I see there is suppose to be rudder/ brake return springs on the rudder assembly. My aircraft does not have those installed. I am wondering if they were not installed on 1948 model 140s? I am also wondering if those springs would normally pull the rudder pedals and brake mechanism further back, thereby preventing the problem I am having? I have experience with Cessna 140s, 180s and L-19s and have never had this problem. Any ideas?

Frank Huber N2486V KANE
User avatar
6597
Posts: 379
Joined: Tue May 01, 2018 7:00 am
Name: David Sbur
Location: Vancouver WA KVUO
Aircraft Type: '46 140 0-200A
Occupation-Interests: Agriculture
Contact:

Re: tapping brakes wih rudder pedal applicaion

Post by 6597 »

Oh my, yes you are supposed to have those rudder return springs. Here's a few pics, they are side specific. I wonder how your pedals aren't just flopping backwards. All models, even the 140A.
rudderpedalsA.JPG
rudderpedalsA.JPG (173.52 KiB) Viewed 4391 times
rudder-springs.jpg
rudder-springs.jpg (127.34 KiB) Viewed 4391 times
User avatar
6643
Posts: 2464
Joined: Tue May 01, 2018 7:00 am
Name: John C
Location: KLCI, NH
Aircraft Type: 1946 C140/C90
Occupation-Interests: A&P, semi-retired
Contact:

Re: tapping brakes wih rudder pedal applicaion

Post by 6643 »

Yes, those springs are the only thing that tensions the rudder cables, unless you are pressing both pedals.

Incorrect adjustment of the cable lengths is known to cause problems with unintended brake application.

The only adjustment is the distance of the pedals from the firewall, six inches, measured from the hinge line of the pedals.
cdoughty
Posts: 48
Joined: Mon Mar 09, 2020 8:51 am
Name:
Aircraft Type:
Occupation-Interests:
Contact:

Re: tapping brakes wih rudder pedal applicaion

Post by cdoughty »

I my opinion is that the cast style pedal is poorly designed. I started with those pedals and had to consciously move my feet on short final so only my big toe was on bottom of pedal.

If you push above the pivot pin you will get brake (perhaps only slightly, but some) , if you push below the pin no brakes. My size 11.5 shoe hit the pedal above the pin with heels on floor. Take your shoe off, put it in the airplane and look at the geometry.

The cast pedal has almost no meat below the pin, so it’s easy to get some unintentional brake. The wear pattern on mine were mostly above the pin. I switched to the newer sheet metal pedals that have a raised bar at the bottom. This bar is all below the pivot pin, so rudder push, heels on floor, only gives rudder with no brake. Switching really improved my landings and roll outs-much less twitchy.

Also note that the rudder and brake geometry is that on full rudder application the top of the pedal moves aft, towards your toes. Depending on how that’s adjusted (via the length of the master cly pin) you might get some natural brake actuation at the limit. I’m not sure that’s a bad thing but that adjustment puts the pedal closer to your toes throughout the travel.

Good luck
6277
Posts: 233
Joined: Tue May 01, 2018 7:00 am
Name: Ray Hunter
Location: Ann Arbor, MI
Aircraft Type: C-140
Occupation-Interests: Retired AF, retired B-17 pilot for Michigan Flight Museum
Contact:

Re: tapping brakes wih rudder pedal applicaion

Post by 6277 »

Take note of the springs, they are not the same! If I recall correctly, one of them is not easy to replace. One of my final approach checklist items. HEAT and FEET. Carb heat and heels on the floor!
meloosifah
Posts: 109
Joined: Sun Aug 16, 2020 11:28 pm
Name:
Aircraft Type:
Occupation-Interests:
Contact:

Re: tapping brakes wih rudder pedal applicaion

Post by meloosifah »

When I bought my 140 I found that someone had used the wrong turnbuckles and it was not possible to apply rudder without brakes. You might check the pedals to validate that you can actually operate them without applying brakes. That would be a cable or turnbuckle issue. The springs are definitely needed as well.
User avatar
hotrodmac
Posts: 71
Joined: Mon Aug 12, 2019 12:33 am
Name: Lance B
Location: Mint Hill, NC
Aircraft Type: C140
Occupation-Interests: I.T. - Current 120-140 Assoc. NC Rep.
Contact:

Re: tapping brakes wih rudder pedal applicaion

Post by hotrodmac »

6277 wrote: Sun Aug 18, 2024 8:22 am Take note of the springs, they are not the same! If I recall correctly, one of them is not easy to replace. One of my final approach checklist items. HEAT and FEET. Carb heat and heels on the floor!
I’m in the process of replacing my springs now. The right-side spring was on back order, it took two months to get then.
Attachments
Rudder return springs
Rudder return springs
IMG_9285.jpeg (362.32 KiB) Viewed 4113 times
'46 C140
120-140 Assoc. NC Rep.
fbh140
Posts: 5
Joined: Sat May 04, 2024 9:20 pm
Name: Frank Huber
Location: KANE
Aircraft Type: 1948 C-140
Occupation-Interests: Retired pilot NWA/Delta
Contact:

Re: tapping brakes wih rudder pedal applicaion

Post by fbh140 »

Turns out there are springs, but the same spring non both sides. I have ordered new ones. There is an adjustment on the pedal to brake hook up. My mechanic is going to see if that might help. I will have him measure the distance between the firewall and brake pedal hinge line, that could be the problem. Thanks for all the good ideas. Frank
Post Reply