7BCM Wheels and Brakes

Bob Turner

Well-known member
Joined
Apr 4, 2018
Messages
488
#1
I thought I had asked this question here, but cannot find it. I have an approval for Grove hydraulics on a 7 BCM, and now need to do a cost-benefit analysis for the owner. I am aware of AD 48-08-02, but not sure it applies. The aircraft currently has some obscure looking hydraulic brakes, actuated by Cub master cylinders.

My question: what if we find a crack? Are these wheels available, and if so, how expensive are they?

Ditto on the brake drums and components?

It would probably take me two hours to do the AD inspection. Is that a reasonable guess? In a shop, that is $200 every hundred hours.
 

Bob Turner

Well-known member
Joined
Apr 4, 2018
Messages
488
#3
No - wheels, calipers, and master cylinders.

I did one on a 7AC three years ago, and owners are still raving about the difference. Slightly different master cylinders.

The DMB wheels have a 100 hour AD on them, which, at $110/hr shop rate, can mount up. And if a crack is found, used wheels are twice as expensive as new Groves.

I was trying to figure out how to convert the Chief, but master cylinder location appears problematic.
 

Bob Turner

Well-known member
Joined
Apr 4, 2018
Messages
488
#5
The heel brakes are on the pedals, with cables in a trapezoid to compensate for rudder pedal movement. Just a quick glance says that changing to fixed heel brakes would be a serious challenge. There may be a way to do toe brakes.

When you mess with proven geometry, things start to get sticky. If all I had to do is put hydraulic cylinders on existing brake pedals it would be easy - almost trivial.