Re: Demo Flight Suggestions

[Ben Jackson]

In article >,
Darrell Clay > wrote:
>review. Obviously, we intend to fly it ourselves before making the
>final decision. Anyone have any suggestions as to what we should do
>during the flight?

See if you can trim it to fly straight and level, hands off, with the
ball centered.

--
Ben Jackson
>
http://www.ben.com/

[David Megginson]

(Darrell Clay) writes:

> The plane (a 1964 Cessna 172-E) we are considering buying arrives
> tomorrow for our hands-on inspection and professional pre-purchase
> review. Obviously, we intend to fly it ourselves before making the
> final decision. Anyone have any suggestions as to what we should do
> during the flight?

1. Have fun.

2. As you mentioned, test *all* of the avionics, thoroughly,
especially if you're hoping to fly the plane IFR. If you have a
glidescope, try flying a practice ILS approach VFR. Make sure that
you can hear the ident for navaids as well (that was a problem in
my Warrior, though not an expensive one).

3. If the air is smooth, trim for level flight, take your hands off
the yoke and feet off the pedals and see how straight the plane
flies and how well the ball stays centred. It will eventually go
off, of course, but you don't want to be in a 20-degree bank in 10
seconds.

4. Do all your PPL stalls, steep turns, slow flight, etc. If there is
a rigging problem, it might turn up that way (i.e. a surprisingly
violent stall or a big wingdrop).

5. Do a simple, four-direction GPS test. Set 75% power for your
density altitude, then fly north (compass heading) for a minute,
write down your groundspeed, then fly east, south, and west, and do
the same. Do not correct for the wind. Average the four speeds
right there, in your head, and you have something close to your
true airspeed. Some caveats:

a. If the TAS is too high or too low, it could simply be because of
a tachometer error.

b. Remember that your highest TAS won't occur until around 7500
feet density altitude.

6. Have fun.


All the best,


David

--
David Megginson, , http://www.megginson.com/

[Richard Kaplan]

Darrell Clay" > wrote in message
om...

> review. Obviously, we intend to fly it ourselves before making the
> final decision. Anyone have any suggestions as to what we should do
> during the flight?

Take the airplane up to an altitude near its service ceiling, practically
speaking about 10,000 or 11,000 feet for a 172. Lots of engine problems
can show up at altitude which are not apparent down low.

--
Richard Kaplan, CFII

www.flyimc.com

[Ryan Ferguson]

Richard Kaplan wrote:

> Take the airplane up to an altitude near its service ceiling, practically
> speaking about 10,000 or 11,000 feet for a 172. Lots of engine problems
> can show up at altitude which are not apparent down low.

Really? Hmm, that's interesting! I've never heard that. What is the reason
for this?

[PaulaJay1]

In article <16772588594cea8dcd1e4785b1122d71@TeraNews>, "Richard Kaplan"
> writes:

>Take the airplane up to an altitude near its service ceiling, practically
>speaking about 10,000 or 11,000 feet for a 172. Lots of engine problems
>can show up at altitude which are not apparent down low.
>

Richard,

I've never heard this before. What are the problems to look for when at up
there?

Chuck

[Richard Kaplan]

"Ryan Ferguson" > wrote in message
...

> Really? Hmm, that's interesting! I've never heard that. What is the
reason


For any piston engine (i.e. normally aspirated or turbocharged), if the
engine is not making maximum power for any reason -- weak cylinder,
induction/exhaust system defects, etc. -- this may become most apparent when
you try to climb to altitude and realize the plane does not have the power
to do what the book says it should do. Loss of power is more obvious in
relation to reduced rate of climb than reduced airspeed. There are planes
out there which simply cannot reach their published service ceiling or
maximum authorized operating ceiling, and the easiest way to verify this is
to go up high. Or to put it another way, if an airplane is capable of
reaching its service ceiling then that is one more datapoint suggesting the
engine and induction system are healthy -- consider this "necessary but not
sufficient" to establish the engine's good health.

For a turbocharged airplane (granted only indirectly relevant to this thread
about a C172), a high-altitude test flight is absolutely essential. Since a
turbocharged engine is worked harder/hotter at altitude (basically the
opposite of a normally aspirated engine), a weak turbo can mask a weak
engine down low and a weak engine can mask a weak turbo down low. The only
way to assess maximum performance from both the engine and the turbo is to
do a "critical altitude test" and assess the altitude at which the turbo
reaches its maximum output. There can also be problems with magneto
firing, anaeroid fuel flow controllers, turbo controllers, and induction
leaks which show up only at altitude.


--
Richard Kaplan, CFII

www.flyimc.com

[Ryan Ferguson]

Makes sense. Thanks for the information.

-Ryan