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1956 through 1986 Cessna 182
Fixed Gear Skylane Buyers
Guide Excerpt
Over the last few years,
the staff of the Cessna Pilots Association has seen a number
of incidents and accidents with Cessna 182 aircraft that
have been caused by lack of knowledge of the aircraft's
systems and idiosyncrasies. The CPA was so concerned about
these problems that I wrote a letter to every 182 owner in
the country outlining what these problem areas are and how
to deal with them. A prospective 182 buyer would do well to
acquaint himself or herself with these system-related
problem areas.
It should be emphasized
that while there are some areas where pilots have had
problems with the 182 due to lack of specific systems
knowledge, overall the 182 Skylane has an outstanding safety
record for an aircraft of its capability. Even a low-time
private pilot can operate a 182 Skylane safely provided he
or she has received a good checkout from an instructor that
knows the 182 well, understands the aircraft's systems, and
does not try to exceed his or her limitations.
Here is what I wrote to
the 182 owners concerning safety aspects of the 182 Skylane:
Dear Cessna 182 Skylane
Owner,
FAA records indicate that
you recently registered a Cessna 182 Skylane aircraft. I am
writing to brief you on several safety-critical topics that
we believe every Skylane owner should know about. Many 182
Skylane owners (even experienced ones) are not aware of
certain important characteristics of this aircraft that are
critical to safety.
I'm going to discuss the
idiosyncrasies of the Cessna 182 Skylane fuel system and
several other aircraft systems. At the end of this letter,
I'm going to tell you a little about the Cessna Pilots
Association and urge you to become a member of this valuable
technical information service for Cessna owners. But whether
you decide to join CPA or not, I want you to be safe when
you fly your Skylane. So please take a few minutes to read
this letter carefully.
FUEL BLADDERS AND
FUEL CAPS
If you fly a 1956 182
thru a 1978 182Q, your airplane uses rubber bladder tanks in
each wing. These bladders have a tendency to develop
wrinkles along the bottom. The wrinkles act as little dams
that can prevent water from moving to the sump drain. You
can sump the tanks at pre-flight and see no water, yet water
could still be present in your fuel tanks.
To make matters worse,
Cessna originally installed flush-style fuel caps on these
aircraft. The caps can leak if the aircraft is exposed to
moisture. If your fuel caps have a small hinged pull-up
handle that fits into a recess in the cap, you have the
dangerous fuel caps. At CPA, we call them "killer caps."
There have been a number
of engine failures immediately after take-off even though
the pilot sumped the tanks thoroughly during pre-flight.
Some of these incidents have been fatal. The FAA issued
Airworthiness Directive AD 84-10-01 to deal with the
problem. It requires inspection of the bladders for
wrinkles, and suggests changing the flush-style fuel caps to
umbrella-style caps.
If you fly a
bladder-equipped 182 that still has flush-style fuel caps,
the Cessna Pilots Association strongly urges you to change
immediately to either the Cessna umbrella cap (kit SK-182-85
available through any Cessna service center) or the Monarch
Development cap sold by Hartwig Aircraft Fuel Cell Repair (phone
800/843-8033 US or 800/665-0236 CAN).
I beg you not to overlook
this fuel cap situation on your 182. Accident statistics
show that the 182 Skylane has one of the highest rates of
accidents caused by fuel contamination and the flush style
fuel caps coupled with the bladder fuel tanks are the main
cause.
CARBURETOR ICE
The Cessna 182 Skylane is
prone to developing carburetor ice. The reason for this is
because the design of the induction system has the
carburetor positioned well below the engine in the cowling
and away from the warm air around the engine. Because of
this tendency towards carburetor ice many Cessna 182
Skylanes were delivered with a carburetor temperature gauge.
The Cessna Pilots Association has strongly recommended to
its members that they utilize carburetor heat in such a
manner as to keep the carburetor temperature indication out
of the yellow zone of the gauge. This may only require the
use of partial carburetor heat, a practice that in
standardized flight training is considered a poor procedure,
being taught that carburetor heat should be all or nothing.
The carburetor icing characteristics of the Cessna 182
Skylane make partial carburetor heat an acceptable practice
for this aircraft.
AUTO GAS
1956 through 1976 model
year Cessna 182 Skylanes can receive STC approval to operate
on auto gas. The makeup of auto gas coupled with the Cessna
182 Skylane's induction system produce a couple of
interesting operating characteristics. First of all because
auto fuel vaporizes more readily than aviation gas it is
possible to develop carburetor ice at higher outside air
temperatures on auto gas than on aviation gasoline. The
amount of ice that is produced remains the same but pilots
will notice carburetor icing occurring at higher air
temperatures on auto gas than they are used to experiencing
with aviation fuel.
Another characteristic on
auto fuel is that when the engine is shut down, remaining
auto fuel in the induction system will condense in the
intake tubes, run back down to the carburetor and drain out
on the ground. The amount of fuel that will drain out will
vary from a teaspoon to a cup or so. Members report seeing
this situation most often in the fall of the year when
conditions are most conducive to producing the condensation
of fuel in the intake. While this is a normal situation when
operating on auto gas, if bothersome to the operator it can
be minimized significantly by idling at a lean mixture with
the carburetor heat on for thirty seconds or so immediately
prior to shutdown.
UNEVEN FUEL
FEEDING
Have you been flying
along and watched your fuel gauges show that your left tank
is going down while the right tank remains full even with
the fuel selector on "Both"? This is a common problem with
Cessna 182 Skylanes before the 1979 model year. And the real
shocker is that while the right tank is remaining full the
engine is actually running off of fuel from the right tank!
What causes the situation
is the way Cessna designed the fuel tank venting system.
When fuel is used from a tank it must be replaced with
something, otherwise a vacuum is created which will either
cause interruption of fuel to the engine or cause the bottom
of the bladder tank to be "sucked" up. To avoid this in
almost all fuel systems, whether they are in an aircraft, a
car or a lawnmower, fuel that is used from the tank is
replaced by air from the outside.
In the Cessna 182 Skylane
this venting occurs by connecting the upper outboard portion
of the left tank to the "L" shaped vent tube underneath the
wing behind the left wing strut. This allows air into the
left fuel tank as fuel is used. To vent the right tank, a
vent inter-connect line is run from the upper inboard area
of the left tank to the upper inboard area of the right tank
thus, in theory, venting the right tank to the vented
airspace of the left tank.
Unfortunately, wing
dihedral, where the wing tip is higher than the wing root,
was not sufficiently considered. When the wing tanks are
full, the vent interconnect line is actually submersed in
fuel and thus as fuel is used from the left tank, the air
coming in from the vent pushes fuel from the left tank
through the vent interconnect line into the right tank, thus
replacing fuel that is used from the right tank. And even
after enough fuel is used from the left tank to bring the
fuel level below the vent interconnect line the condition
will continue as fuel sloshing in the tank periodically gets
into the interconnect line and pushed through to the right
tank.
In really severe cases
fuel usage from the right tank might not be indicated on the
gauge until the fuel level in the left tank is as low as 1/3
capacity. The positive thing to keep in mind when
experiencing this condition is that fuel is actually being
used from the right tank and that fuel being used from the
right tank is merely being replaced by fuel from the left
tank. This means that even if the left fuel tank should go
to empty you will not experience fuel flow interruption as
long as there is fuel in the right tank and the fuel
selector is on "Both".
This condition can be
minimized somewhat by adjusting the position of the fuel
vent behind the lift strut on the left wing, making sure
that fuel caps seal tightly so that the "head pressure" in
one tank is not altered by a leaking cap, and assuring that
the wing strut fairing is sealed against the strut, thus
avoiding burbling air right in front of the vent. However,
in the end the design of the system does not allow for
complete resolution of the problem. The Cessna Pilots
Association has a handout available to its members that
discusses this situation in even greater detail.
Beginning with the 1979
model year the Cessna 182 Skylane went to an integral bay
"wet wing" fuel system with vents under both wings which
went a long way to reducing the problem.
DRIPPING FUEL
FROM THE VENT ON THE
GROUND
Earlier I mentioned that
the fuel tanks are vented to replace the fuel being used
with air. To prevent fuel from going the other way, that is,
fuel leaking out the vent when the tanks are full or the
left wing with the vent is lower than the right wing, a
check valve is installed in the vent line.
However, fuel is not a
totally stable product, it will contract when cooled and
expand when warmed. This means that if your aircraft is
topped off with cool fuel from an underground tank and your
caps sealed tightly and your check valve sealed tightly,
then as the fuel warmed and expanded there would be no way
to relieve the pressure and eventually the tank and perhaps
some wing rivets would fail. To prevent this Cessna uses a
check valve with a small hole in it to allow fuel to drip
out the vent line when pressure builds up in the tank.
Normally this drip will
stop when the fuel cools or the fuel level drops a little
bit. However sometimes the pressure can build up so rapidly
that a solid stream of fuel can come out the vent which is
situated below the tank and a siphon effect can be
established where several gallons will drain out before the
stream stops. In addition if the aircraft is parked in such
a manner that the wing with the vent is on a low side then
fuel could continue to siphon for some time as the fuel
siphoning out of the tank is being replaced by fuel from the
other tank passing through the vent interconnect line.
A FAA Airworthiness
Directive required the use of fuel caps that have vents
installed in them in case the primary venting system became
blocked by such things as bugs or ice. These cap vents are
only secondary vents that are normally closed and only open
if a vacuum is being created in the tank.
SEAT TRACKS
There have been a number
of accidents caused by the pilot's seat slipping aft just as
the aircraft rotates. Normally the seat is kept from sliding
after the pilot releases the latch by one or two pins from
the seat that fit into holes in the seat tracks. However if
the seat tracks or seat latching mechanism become worn, the
pin may hang up on the edge of the hole and not be fully
engaged thus allowing the seat to slip when the nose of the
aircraft pitches up. The FAA issued Airworthiness Directive
AD 87-20-03 R2 which calls for seat tracks and latching
system inspection at every annual or 100-hour inspection.
The Cessna factory now has available a secondary seat
latching system which will catch the pilot's seat if it
starts to slide. The secondary seat stop system can be
installed by any Cessna
Service Center.
A good habit to get into
is having a "Cessna Fanny". That is every time you pull the
seat into position on a Cessna single engine aircraft you
wiggle your hind end to try to dislodge the seat from its
latched position.
AND NOW...A WORD FROM
YOUR SPONSOR
The Cessna 182 Skylane is
a great aircraft. It has great load carrying capabilities,
moderate speed, and relatively easy maintenance. But as with
any mechanical device, time and service have shown that
there are areas of concern that owners/operators need to be
aware of. Which is why the Cessna Pilots Association exists.
The principal purpose of
the Association is to provide our members with in-depth
technical information about their aircraft that is simply
not available anywhere else. Members receive our monthly CPA
Magazine; each 32-page issue is jam-packed with news,
technical articles, details of ADs and service bulletins,
service difficulty reports, general aviation alerts, and
other vital Cessna-specific information.
CPA also has developed a
long list of informational handouts that deal with the most
frequently-seen problems and frequently-asked questions
about Cessnas: nosewheel shimmy, oil on the belly, uneven
fuel feeding, and many other subjects. These handouts are
available at no cost to CPA members.
One of the most valuable
aspects of CPA membership is access to the CPA Technical
Hotline. CPA is the only Cessna owners association with a
full-time staff of A&P mechanics available daily to answer
your questions. Each one is a real Cessna expert. We also
maintain the largest Cessna technical library outside of the
factory. If you need help troubleshooting an elusive problem
or locating a hard-to-find part, we can help. We can also
save you big money on high-ticket parts by telling you where
to get the best deals.
The Cessna Pilots
Association also has a great aircraft insurance program
managed by the Falcon Agency. Should you wish information on
the program, call Falcon's Bob Haag at 800/880-2727.
If you join CPA and call
with a 182-related problem you'll wind up talking to one of
our Tech Reps. Their job at the Cessna Pilots Association is
to provide technical support to our members who own 182s.
They know the aircraft intimately and can answer almost any
182 question you might have. If our Tech Rep doesn't know
the answer, he knows who knows.
CPA also offers a
terrific two-day Cessna 182 Systems and Procedures Course.
The seminar is given several times a year at the CPA
Technical Center in California, and once a year in several
other parts of the country. Our instructors are all
world-class 182 experts. When you graduate from this course,
you will know more about your Skylane than 99% of all 182
owners, and you'll probably understand its systems better
than most A&Ps do. There is no better way to learn so much
about your aircraft so quickly.
CPA membership costs just
$55. Most of our members feel that CPA membership is one of
the best bargains in aviation. But whether or not you choose
to join CPA, please pay careful attention to the information
in this letter, particularly the cautions about fuel
contamination. The 182 has a history of fuel-contamination
accidents. A little knowledge and reasonable caution will
prevent you from adding to the statistics. It is easy to
join, simply fill out an application or call our
Headquarters at 800/343-6416.
Lets All Of Us Be Careful
Up There,
John M. Frank |
