Help me study - Instrument Oral Guide

[evh347]

Larry, Jeff...and anybody else. :)

I'm studying for my Instrument Oral and I received a little guide compiled by the various CFIs and had been going around the airport. It contains a broad selection of questions that the examiners have been asking during the orals. I was wondering if you might be able to help me answer a few of the more obscure (the ones I don't know)...here goes:

1) What do you do if your Pitot static and alternate static source doesn’t work?

2) Does the Kohlsman Window push on the aneroid wafers?

3) Why is the Pitot tube always on the left wing?

4) If the static system is inoperative, will the transponder still work?

5) Why do you still hear the marker beacons if you fly over them with out the localizer frequency tuned in?

6) How much does oil weigh?

7) How much does the VSI lag?

8) Three things that determine 180h.p?

9) What does “0000” mean in the transponder?

http://www.flightsim.com/dcforum/Use...0a18b677a8.jpg

[Jeff S KDTW]

>1) What do you do if your Pitot static and alternate static
>source doesn’t work?

Textbook suggestion, break the face of the VSI. However, in the realworld, you better have something pretty hard in your flightbag to do it, cause it "ain't" easy.

>3) Why is the Pitot tube always on the left wing?

So the pilot can see it

>5) Why do you still hear the marker beacons if you fly over
>them with out the localizer frequency tuned in?

They are two different systems. The beacons do not broadcast on the localizer frequency.

>6) How much does oil weigh?

7.5 lbs/gal (4 quarts=1 gal)

>7) How much does the VSI lag?

I don't think this is universal. But from my experience it lags 1-2 seconds in a normal climb/descent.

>9) What does “0000” mean in the transponder?

Typically just a test mode, as far as I know.

[Hakan_Olsson]

I'll have a go straight from memory but I warn you, I can be wrong :-)

1: Open a window

2. Yes

3. It doesn't have to be on the left wing, it depends on the type of aircraft. Some supersonic types have two pitot tubes, one in the nose and one on the fin, one for subsonic flight and one for supersonic flight

4. Yes but it won't show your altitude correctly

5. Because you've pressed the marker button on the audio panel

6. The specific gravity for a single grade oil used in piston engines
is about 0.89.

7. It's depending on the which type of VSI we're talking about, a VSI fitted to a glider is a totally different creature than what is fitted in powered planes, but my answer is that there is a 1-2 second lag in the system.

8: ??? I'm stuck here, I don't understand the question

9. SSR data (Secondary Surveillance Radar) unreliable.

I hope my answers can be of som help.

Best regards,
http://www.flightsim.com/dcforum/Use...741259b532.jpg

[evh347]

Ha, ha..."Why is the Pitot tube always on the left wing?"..."So the pilot can see it."

That's what I said Jeff, but that's not the right answer. These questions are wierd because the most obvious answer isn't the correct answer. One of my friends who got this question tried to explain the answer he got from the examiner was something more down the line of where the pitot tube sits in relation to the propwash and so forth. It's not always where the pilot can see it, because you have to remember that on some of the low wing airplanes (Piper Archer), the pitot/static mast is located underneath the wing. The only way the pilot is going to see that is with X-Ray vision.

And you can tell the examiner is sitting there all excited about how "he's never going to get this one correct". It's as though he's primed to jump out of his chair the moment he sees you give the answer he completely expects..here's another example:

"You are doing a timed turn to the left from 360 all the way back to 360. You are 5 sec. into the turn and you bump your timer and it stops what do you do?"

The first thing that comes to my mind is that okay, 5 seconds has gone by...start your time and when 1:55 has elapsed, stop your turn.

Nope, that's not correct. You see, you grab the timer and fumble around the buttons and now more than 5 seconds has gone by. What do you do? Here's what you do...the magnetic compass indicates correctly on Westerly and Easterly headings. You start your time on West and after 1:30, you roll out on North.



http://www.flightsim.com/dcforum/Use...0a18b677a8.jpg

[Jeff S KDTW]

"Why is the Pitot tube always on the left
>wing?"..."So the pilot can see it."[/i]
>
>That's what I said Jeff, but that's not the right answer.

Whoops, I initially had that in there, but thought I erased it when I considered Pipers.

Anyway, I thought you didn't have the answers and you needed help? Were you just testing us?

[evh347]

Jeff,
No, I really don't know the answers. The pitot tube question was one that I was only told that I was incorrect and they gave me a hint...but I don't know the answer.

http://www.flightsim.com/dcforum/Use...0a18b677a8.jpg

[Jeff S KDTW]

>>3) Why is the Pitot tube always on the left wing?

The strange thing is that the pitot is NOT ~always~ on the left wing. Sometimes, pitots aren't even on ~a~ wing (note most airliners).

Hummmm........

[Jeff S KDTW]

I needed to do a little research on this one.

>2) Does the Kohlsman Window push on the aneroid wafers?

Technically speaking, the question is phrased a bit awkwardly--the Kohlsman Window does not ~push~ on anything. It is simply just a stationary clear piece of glass or plastic. :-)

But, what I think you meant to say was, "does the barometric setting mechanism push directly on the aneroid wafers?"

In response to that question, from what I can see, no. (Hakan and I disagree here). Any cross sections I've been able to find (which are not very clear) illustrate a series of gears that are used to adjust the display needles--however, these gears are "downstream" from the wafers. See http://www.faatest.com/books/IFRH/4-0.htm

It is also important to note that the wafers are ~~very~~ delicate, which makes them good for the task at hand. Pushing on them directly using anything other than internal air pressure would most likely damage them.

If anyone has more information on this one, I'd be interested to read it.

[flyinggriffin]

The question about horsepower is tricky. Do you mean what determines if you get 180HP out of your engine, or what goes into designating the engine 180HP.

The same basic Lycoming engine is used on the C172R and SP. The S model is uprated. This can be by way of a different prop, a new tach with markings and a change to the aircrafts type certificate. The engine in a Piper Archer and a Skyhawk is still 360 c.i.

This is done on older model Cessnas to upgrade them all the time. Makes a big difference in performance when you don't have the extra "fat" the newer Skyhawks have.

[evh347]

Here's the actual answer (I just found out)

Horsepower is determined by and assuming it's a brand new engine, running within the first 5 minutes of true operation:

1) Sea Level Pressure
2) International Standard Atmospheric Conditions (ISAC), which is 15 degrees celsius and 29.92
3) 270o RPM



http://www.flightsim.com/dcforum/Use...0a18b677a8.jpg