CFO Members in Depth
Members In Depth
Paul's new Engine
Paul Millner's New Engine
Most if not all of you know Paul Millner as our capable and (usually)
patient moderator of the CFO email digest. And most of us read with
interest of his '76 RG's triumphant return to the air after a bird strike/spinner
failure was finally repaired. All pictures can be clicked on to load a larger image. |
Of course it was only good news for a short while, as a long festering
gear rigging problem reared it's ugly head, causing a nose gear collapse.
The issue is a simple one, the fix nearly free. It's an excellent item
for each of us to check at annual. This page contains some information on
But of greater interest are the other consequences of this event. For Paul
rarely takes the easy way out, seeing opportunity where others see only
problems. Paul took this opportunity to convert his RG to the separate magneto
These photos answer several questions: How's the project coming? What caused his gear problem? What does the back of a non-dual
mag look like? What's all this about an oil filter adapter? Read on for the answers.
For those of you who missed the story, Paul had just completed a cowl repair
brought on by the loss of a spinner in flight. Check out this page for pictures
of that event.
After landing, as he was taxiing in, his nose gear collapsed. The problem turned
out to be three-fold: |
So as is so often the case in aviation incidents, more than one thing was wrong,
in fact the more normal 3 things were wrong in this case.
- The nose gear uplock indicator switch was shorted. This is the magnetic reed
switch that closes when the '76 landing gear is either completely up or completely
- The wire to the uplock indicator switch had moved out of it's correct position.
This had two consequences:
- First it hammered the insulation over time, finally
causing the wires to short together (that's what caused the first item.)
- Secondly, the extra layer changed the uplock geometry of the uplock eccentric.
This is the switch affected by the presence of the small rubber strip that most
RG's need to replace every few years. It had the same effect as having a rubber
strip far too thick, changing the downlock force. Check out this page for
information on this rubber strip.
- Finally, Paul's gear pump had started to cycle more and more often. This is
an indicator that the system had begun to develop one or more small internal leaks.
The gear pump should cycle every hour or two in the air, on Paul's airplane it was
down to about 6 minutes per cycle.
The means that after the nose gear touched the ground and opened the squat switch,
within 6 minutes the hydraulic pressure had fallen to the point that it was no longer helping hold the nosegear down, relying on the downlock force to do that.
For those of you celebrating your ownership of a fixed gear aircraft as this
story unfolds, let us point out that with over 1000 Cardinal owners and flyers
on the list for over three years, we have not heard of this situation occurring
in our collective memories. At least not until this article smokes one out..
somehow there is always one!
I happened to be in town when Paul's new engine came into his repair shop. The
picture to the right shows the engine being unloaded from the truck. It was a
rather exciting process, with the tines of the fork truck pointed directly at the
$29,000 engine as he struggled with a sticky clutch and uneven ramp.
Paul took advantage of this event to change his engine from an IO-360-A1B6D to an
IO-360-A1B6. The difference is primarily in the accessory case, which has two
separate mags rather than the single dual mag. The dual mag has a reputation of
sorts due to it's reliance on a single internal plastic drive gear to run both
mags. Should that gear break or something physically come loose in the mag,
it is likely that both magnetos would come off line.
Finally the engine was firmly engaged on the forks and gently lowered to the
hangar floor, the lid removed and the inspection process begun.
The A1B6 engine, with separate mags, provides full magneto redundancy. There
are a few modifications that need to be made to use this engine, but the legalities
are easy: it is a simple log book entry since the '71 RG was originally certified
with this engine.
As can be seen in the picture to the right, the accessory case looks quite
different. Most significant is the lack of an oil filter. The oil screen that
is evident in the picture can be replaced with an adapter that allows for
use of a spin-on oil filter, although a different type than the filters that
fit the A1B6D engines, as can be see on this page.
Of course there is more to a project like this than simply unbolting one
engine and bolting on another.
For one thing, any issues with baffling
seem to become very apparent when the little bits are all off on the floor.
Some have been repaired many times while others were never correctly
modified for Paul's turbo and some were badly worn.
To the right can be seen most of the baffles, laid out for inspection.
They will be repaired or replaced, sent out for powder coating and
reinstalled as the engine goes in, along with new silicon baffle seals.
The shop that Paul's insurance company highly recommended seemed very
thorough in their inspection and capable in their repairs.
been some discussion of the cost of these parts from Cessna, but this
shop simply makes their own. They are hand-built, a task requiring some
craftsmanship but not beyond the ability of most owners, given time and
There were also a number of parts to order from Cessna. One of the
nose gear side doors was available as can be seen to the right. The
other one is still being located, with the option of repairing the
old one remaining as a possibility.
This is the new nose gear door that arrived from Cessna. Paul has mentioned the
extra tab on the bottom of the door in the digest, wondering if that tab would
protect the door from hanging up should the door link fail in the future.
Evidently one of the tricky parts of the process is trimming the gear door
to fit the opening it should go into. This is a trim-to-fit part, and requires
a little extra effort to make fit properly. Check out this page for information on this process.
All in All, Paul's airplane looks like it may yet get put back together. And
by the time he's done he'll know even more about the Cardinal. Now that is a
frightening thought.. :-)
Keith Peterson, CFO Webmaster
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