April 24, 2017

Cardinal RG Operational Hints and Tips

Cessna designed the Cardinal as the replacement for the 172 Skyhawk. They moved the wing back for better visibility, gave it much wider doors and set it lower to the ground for to make it easier to get in and out. However, when the original 177 fixed gear model came out in 1967 it became apparent the 150hp engine that had worked well enough in the Skyhawk was inadequate for the Cardinal. Design changes were made over the next several years but the Cardinal never recovered from the bad reputation it received in it’s first few years of production.

The RG was introduced as a 1971 model. Chandelle’s plane was assembled in December 1970 and was the 35th 177RG built – explaining the 035G tail number.

Here are a few things you might want to know that could save much frustration when you fly the Cardinal.

Fuel System

The 1971 model Cardinal has what I call the 152 fuel system – it’s either On or Off. You do not have the ability to choose left or right tank.

Tank vent lines are located at the trailing edge of the wing tips, just outboard of the ailerons. The right wing vent goes to the left side tank and the left wing vent goes to the right side tank. To check the vent lines, I blow air into the vent line with my mouth to pressurize the tank, then turn my head slightly so I can feel the escaping air on my cheek. If there is a blockage, you won’t be able blow air into the vent line. I’ve had good luck running a long piece of .095 diameter string trimmer line up the vent to clear blockages.

MOST IMPORTANT FUEL NOTE!

When you completely fill the tanks up, a small amount of fuel gets into the vent lines and puddles at the low point in the system. When this happens, the tanks cannot cross feed and fuel is drawn only from the right tank until that tank is practically empty. Only then it will suck the errant fuel out of the vent line and allow fuel to equalize between tanks.

In the meantime, don’t freak out because the fuel gauges show you have one full tank and one empty tank. This is a known issue with early model Cardinals. Later models got the right-left-both fuel selector. As long as you have fuel in eithertank the engine will continue to make noise.

Water In The Fuel Tanks

Cardinals also originally came with flush fuel caps that worked extremely well as funnels for adding rain water to the fuel. The Chandelle Cardinal was retrofitted at some point with 152 fuel necks and caps to reduce the problem.

Since the plane is hangared, this isn’t usually an issue but we have had times in the past when the plane was away from home and tied down outside in the rain. On the post-rain preflight, at least a pint of water was drained from one of the tanks. If you get water in the sample cup, just keep drawing samples until it’s all gone. Then rock the wings vigorously and take another sample to make sure you got it all.

We replaced the fuel cap gaskets and that seems to have fixed the problem. The gaskets will harden over time and eventually fail to create a perfect seal. Happily they’re an inexpensive item.

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Hot Starts

It’s possible the Cardinal will be the first plane you’ve flown with a fuel injected engine. The starting process may seem counter intuitive and a bit daunting at first but after you get used to it, carburated engines will seem primitive and clunky. That is, until you face the dreaded hot start – then you’ll long for the simplicity of the 1930’s designed Marvelous Dribbler updraft carb in the Warrior or Archer.

What is a hot start? It’s when you land and are planning a quick turn around. You’re picking up or dropping off a passenger or are stopping for fuel on a cross country. When you shut down the engine, since there is no more air movement through the cowling, the heat builds up on top of the engine where the fuel injection lines live. The fuel in the lines begins to boil, forcing fuel out of the injectors which puddles inside the intake manifold. So when you jump back in and follow normal starting procedure, you squirt even more fuel into the system and the engine will not start until the excessively fuel rich situation is cleared. You can exacerbate the hot start issue with extended cranking of the engine to clear the fuel which can leave you with a dead battery and altered travel plans.

So how do you avoid the dreaded hot start? Quite simple with a little advance planning! Just prior to shutting the engine down, set the throttle for 1200rpm and then pull the mixture to idle cut-off. For the re-start, TOUCH NOTHING!! Just master switch on, aux fuel pump on (on the checklist, but not really required) and turn the key. It should catch right away and then advance the mixture until you have a smooth idle.

An optional procedure that I perform is to open the oil door on the cowling while refueling. This allows heat trapped in the engine compartment below the engine a fast way to escape.

Retractable Landing Gear

coming soon