Monthly Archives: November 2017

Change for Cessna Short Stack Installations

November 10, 2017 – After feedback from installations in the field and our own experiences in-house, we have implemented a change in our installation that affects C172, C175, and C177 fixed gear aircraft with short stacks.  Over the years we received a few reports that the installation of the Power Flow exhaust short stack could result in the exhaust stack not being centered when coming out of the existing cowling hole.  When this occurred, it was typically displaced to the outboard side.

Typical Stock Exhaust:


The Power Flow as originally installed, pre-modification:


To address this, beginning with kits that were shipped in October, we have added an additional step to trim the 4 to 1 (the part that the short stack slides onto on the main heater section) slightly to allow for a more centered placement of the short stack.


This change also affects aircraft with the classic installation, however the tube coming out of the cowling on the classic installation is a 2.0 inch diameter instead of a 3.0 inch diameter, so displacement was not noticeable and had not been reported.

This will result in a nicer looking final product, easier installation and improved clearance for exhaust fairings.

We are always striving to make all our products, both future and existing, the very best we can produce. We always appreciate feedback from our customers, as it helps us to achieve this goal.

Changes to 1967/68 C177 with Lycoming O-320 and/or Original First Year Cowlings

November 10, 2017 – One of the many things that are unique to the first year of C177 aircraft is the cowling. The lower cowling has an integral airbox built-into the cowling, as shown in the image below.


The cabin heat source is an oval shape designed for a 3.0 inch diameter SCAT tube.


On the original Cessna exhaust system, there is sufficient clearance for the SCAT tube to work its way over to the original exhaust’s cabin heat source.


The Power Flow second generation shroud was designed to fit all models of the C177 aircraft from 1967-1977.  Unfortunately, we weren’t aware of the difficult job of routing the 3.0 inch SCAT hose through what turns out to be a 2.5 inch space.


Installers in the field would have to squash the SCAT hose to get into the tight clearance and then rapidly turn the tube up at a 90 degree angle to go into our shroud.


Clearly this is not ideal and can result the SCAT tube rubbing against the aluminum airbox.  We are sorry to say that we weren’t aware of the magnitude of the problem until recently. So in our relentless pursuit of perfection, we have implemented a number of changes in a complete redesign of the shroud exclusive to the first year Fixed Gear Cardinal.

– The cabin heater input is now an oval tube that comes out of our shroud at a right angle and extends over the shroud.


Here is the view as installed and seen from the left side:


Here is a view of the new clearance to the airbox:


– Originally, the carburetor heat came out at an angle that was awkward for the 1968 cowling, resulting in a lot of carb heat SCAT tube twisting as depicted below.  Note how close the output is to the input.   


Here is the new carburetor heat output – it allows for a shorter length of tubing that doesn’t have to twist or turn nearly as much:


– The original 1968 C177 uses a very long throttle arm – too long in fact to allow full travel in some instance as pictured below.


The solution?   Trim the throttle arm to remove the furthest hole and move the throttle cable to the middle arm.  Problem solved.  This step will be incorporated into our installation instructions.  See the below picture for the final results.


One more change on the way:

We are going to change the cabin heat output to angle down and outboard so that the 3.0 SCAT hose can work its way around the mess of fuel hoses and header tubes and enter the shroud on the lower left hand corner.

Customer shipments for 1968 Cardinals starting in January 2018 will have the new shroud design.  Any existing C177 can replace with the latest shroud starting then as well.

We hope you like the changes! We are always striving to make all our products, both future and existing, the very best we can produce. We always appreciate feedback from our customers, as it helps us to achieve this goal.

Thank you!