The International Cessna^® 170 Association

I am having trouble keeping my parking brake operational. I've heard, but can't find, that there is an upgrade of modification out there to remedy this problem. Does anybody know of a mod or a fix for these unreliable parking brakes?

Thanks.

Well to start, most of us recommend you remove the tabs from both master cylinders which are a key component of the stock parking brake thus rendering the brake inoperative. The reason is that these tabs have been know to be engaged inadvertently and unknown to the pilot who then lands with a locked wheel resulting in a ground loop.

The modification you seek involves adding an additional master cylinder and J handle to activate it. This is the system used in later Cessna aircraft as well as Piper.

See this: http://www.cessna170.org/forums/viewtop ... ake#p72464

Most of us use a pair of wheel chocks.

Wheel chocks work well until you are solo and have to stop on a hill in a back country air strip.

dj2790 wrote:I am having trouble keeping my parking brake operational. I've heard, but can't find, that there is an upgrade of modification out there to remedy this problem. Does anybody know of a mod or a fix for these unreliable parking brakes?

Thanks.

DJ2790, It is highly advisable to INOP your parking brakes. Over the history of the airplane there have been to many incidents attributed to this. The most recent was a few years ago, so rather recently. It was done by a relatively new 170 owner who didnt understand the warnings that were provided on this forum. It is one of the best practices on the TICA 170 website to disable the parking brake. Most people will make a set of chocks out of PVC pipe and throw them in front of the tires. They are light and cheap to make. Use 3/4 inch PVC pipe available at the hardware store. Kindest, Doug

blueldr wrote:Wheel chocks work well until you are solo and have to stop on a hill in a back country air strip.

Blueldr, you never tied a string to your chock and threw it out the window in front of your tire being a back country guy?

There must be a number of types of parking brakes fitted to the 170 by the sounds of it. my parking brake has the old style umbrella handle but connected to a single cable which then forms into 2 cables then which each one runs to a single master cylinder. By pulling the handle the cable then pulls each master cylinder rod down and pedals down also and the handle then locks trapping the pressure in the lines . There are no tabs to lock etc. Sometimes I have to lock my park brake on in flight due to a wheel rotation in flight which creates a rumbling through out the air frame . My pre landing has a line saying "Park Brake Off" plus I put a small paper reminder on the combing panel also.

Hmmm. We need a picture of your parking brake system.

The tabs don't pull down on the rods in the normal B model (or the master cylinders found after the serrated rod style).The tabs are positioned by the cables being pulled, into a position to jam and hold the rods in after they are pushed by someones feet.

Releasing the pull handle does not release the rods alone. You must push the brakes on to release the tabs and release the rod and the pressure.

This is why when the tabs are inadvertently positioned to keep the rod down it is not intuitive for the pilot to release them. The pilot wants the brake to release and released foot pressure on the pedal when in fact he needs to jab the brake on to release it.

Ghost flyers remedy sounds like a later style 172 park brake system has somehow been grafted into his airplane, which to me also sounds like a reasonable solution if you really need a park brake. And sometimes I know I have had the need when alone.

I ran across a guy at Sulfur Creek Ranch in Idaho, on their sloping parking area, who had rigged a pair of "Lock off" parking valves controlled with Bowden Wire controls. The valves were under the floor so I didn't get to see them, but he explained how the job was done. When I asked about authorization and approval, he gently explained as to how the people in the FAA were VERY busy and he just didn't have the heart to interupt their very important other work.
Obviously a real man after my own heart.

Real men who need parking brakes fly crosswind landing gear.
Just kick one wheel out and the plane won't roll anywhere.

ghostflyer wrote:There must be a number of types of parking brakes fitted to the 170 by the sounds of it. my parking brake has the old style umbrella handle but connected to a single cable which then forms into 2 cables then which each one runs to a single master cylinder. By pulling the handle the cable then pulls each master cylinder rod down and pedals down also and the handle then locks trapping the pressure in the lines . There are no tabs to lock etc. Sometimes I have to lock my park brake on in flight due to a wheel rotation in flight which creates a rumbling through out the air frame . My pre landing has a line saying "Park Brake Off" plus I put a small paper reminder on the combing panel also.

This is the parking brake system my 1958 C180 has. You do not need to put pressure on the pedals to either lock or unlock the parking brake. It is a very reliable system and has very little potential to inadvertently lock in the on position as the handle must be pulled out several inches and then turned 90 degrees to lock.