Ask a Flight Instructor

Archive for July, 2008

Received a question this morning from Jim:

When flying a piston single (e.g. C172), I’m trained to do a run-up before every leg of every trip. I can understand the value of a runup before the first leg of the trip — you want to be sure the engine is running fine. I’m less clear about why we do a run-up after landing after a pee break on a long cross-country flight. What exactly is the run-up testing for? What problems in a second or subsequent leg of a day’s flying is it intended to catch?

You have asked a great question Dave that I am sure a lot of pilots have wondered at one point or another.  Isn’t just one engine run up per day or per trip enough?  Why do I have to do it every single leg?

For those who may be just getting into aviation let me quickly explain a engine run-up.  A engine run-up is referring to a series of checks a pilot does before takeoff.  On a single engine piston aircraft (like a Cessna 172) a engine run-up consists of usually of checking the aircraft’s carburetor heat and a quick check of the airplane’s magnetos as well as the basic engine instruments such as oil pressure, oil temperature and cylinder head temperature.

Why these checks are necesary:

Carburetor Heat: Carburetor heat is necessary when operating at lower power settings where you might experience carburetor icing.  Applying carburetor heat is usually as easy as pulling a single knob control in the cockpit.  When you pull that knob you redirect hot air taken from a shroud around the exhaust system into a duct and directly into the air induction system which would melt any carb ice which might have built up.  The less dense air entering the engine causes it too lose approx. 75 -100 RPM which is what you should see on the engine RPM gauge during the check.

But what happens if you don’t see a RPM drop?  I could mean a few things.

1) It could mean a broken cable between that knob and the valve in the airbox

2) It could be a stuck valve in the airbox. Maybe it is already open (which is why you didn’t see a drop) or it could be closed, just not moving.

3) Or it could be something else.

Maybe one of those things (like the broken cable) happened to occur on the last leg.   It might have been loose during your trip and finally disconnected itself during your landing (I’ve had landings hard enough that I wondered if the wheels were still attached).  Wouldn’t you want to find out exactly what was wrong before the next flight?   Do you also know that running with partial carburetor heat can be worse than none at all? (under certain atmospheric conditions).

Magnetos: Magnetos are mounted (usually) on the back portion of a piston engine.  This is where the electrical charge (for lack of better word) for our ignition system and spark plugs originate.   A magneto is a rotating magnet (duh) and as the magnet turns it excite a fixed coil of wires that send out current to the correct spark plug at the correct time.  The current is just great enough that it causes the electrons to “jump” across the gap in the spark plug which creates the spark that ignites the air / fuel mixture in the cylinder, producing power that turns the prop. Most airplanes are equipped with two magnetos.  Each magneto fires the “upper” side of the spark plugs on one side of cylinders and the “lower” side of spark plugs on the other side of cylinders.  That way if you lose one magneto you would still have ignition on all cylinders.

Why a magneto check is important before EVERY flight

Most general aviation airplanes can and do start on a single magneto.  When you place the switch in the start position you are only opening the ground for one magneto, not both.  During your engine run-up you are checking to make sure that yes, both magnetos are really working and falling within required tolerances.  Maybe you accidentally taxied out with the magneto switch in L side only.  You wouldn’t want to takeoff like that right?

P-lead – The P-lead is a way to ground the magneto (turn it off).  If for some reason the P-lead would break during a flight  the magneto…well, it could never be turned off.  That means your prop is always “live”.  Even turning the prop by hand on the ground could technically start your engine and seriously hurt or kill someone.  We also check for this after the flight by turning to magneto / start switch to off momentarily to make sure we can ground the magneto and kill the engine.  I have had this break on me before.

Carbon Deposits – When you cycle a magneto off during the check you are anticipating a certain RPM drop associated with running the cylinder on half ignition.  If you notice a significantly higher drop in RPM it could be a sign you are experiencing some form of carbon (unburnt fuel) deposit in that spark plug gap that we referred to earlier.  To correct this we would want to lean out the mixture and increase power to try and “burn off” that excess carbon.  You want to make sure that before flight you have each and every cylinder firing and producing peak power.

I hope I’ve help to explan the importance of the system checks and why we want to do these checks before each and every flight.

And thinking like a professional pilot for a second here, you also have to remember an important aviation rule, CYA.  If for some reason you didn’t do the required checks as specified by your POH or AFM it could open yourself for litigation and investigation if something would happen during the flight that resulted in injury to someone or something because you failed to do an adequate before takeoff checklist as prescribed by the aircraft manufacturer.  This shouldn’t be your motivation for doing the engine run-up but we live in the age of litigation so you always have to be careful and thourough.

Good luck out there and remember to do your engine run-up before each leg and always…

Fly Safe.

If you have followed this site for any length of time, you’ll probably recall how Ask a CFI used to be forum based.  In fact, it has had a forum feature on / off since 2001 when I registered this domain.  I have tried out a couple different types of forum software in the last few years.  The first one was Dcscript’s DCforum.  I then switched to the more popular Vbulletin forum script.  One of the needs I recognized was that the vbulletin “theme” would have to be customized for the aviation community so I drafted a rough sketch and paid a vbulletin designer to tweak and customize the style.   Ask a CFI.com is no longer utilizing the forum feature and I thought it wasteful to let a good theme sit idle.  So I am now giving away a FREE Aviation vbulletin style to those who might be interested.

A couple of rules / notes.

1) This file is AS IS. I am not providing ANY support for this theme.  Why? Because I have a lot of projects going on and I am not a VB expert AT ALL.

2) The lastest version of vbulletin used with this theme was 3.6.9.  I have no clue if it is comptabile with anything before or after.  (see note 1)

3) I ask that you please leave a link to my site in the footer.

So as long as you agree to these 3 rules, here is the file for you:

Download: vb aviation style.zip

Instructions: Extract this zipped folder to your local drive and then upload the images folder to your vbulletin directory. Go to style manager in your vbulletin administration and upload / download styles. Browse to aviation-style.xml and you should be good to go! Good luck.

This question comes Michael:

I passed my IFR written nearly two years ago but failed to complete my training due to some  issues. I have to take the written again because the old test will soon go beyond the two year expiration. Is there a limit to the number of times you can take a written examination?

Hi Michael, thanks for your question concerning FAA written tests.

No, as far as I am aware there is no limitation to the number of times you can take the test.  As you know the limitation on knowledge (written) tests are:

• Must take the applicable practical test within 24 months of passing the written (14 CFR 61.39)
• Have to get a passing grade (FAA Testing Matrix)
• Don’t cheat (14 CFR 61.37)

One thing, I do want to add is that the question bank changes.  You want to make sure that if you are going to retake your instrument written knowledge test that you look over the most recent question bank.  Here is a link to the current FAA test questions for an Instrument Rating.

Good luck with your (re) test and instrument training.  If you have any questions, you know who to ask.  And remember to…

Fly Safe.

This question comes from David:

How do you find an intersection that is off the airway your on without GPS/loran or a vector from ATC.  For example, let’s say your over PXN (cental california) cleared to the Oakey intersection.  Once I set up my radials to identify the fix, how do I estimate my ETA at Oakey without knowing the exact distance?

Thanks for your question David. To answer you question, I created a video tutorial showing you how to use a easy to remember rule of thumb that works especially well if you course is north-south (such as it is in your case).   I hope this helps.  Let me know if you have any other questions and remember to…

Fly Safe!

By the way, if you are curious about the desktop ruler I used in the demonstration, it is available at:

http://www.askacfi.com/tools

Received a question this morning from Kelly:

Hi. I am a multi-commercial, instrument rated pilot who received my training through the Air Force. I also have a single engine airplane private license which I got before I went into the military. Here’s my question? Do I have to take a checkride with an examiner to get a SINGLE ENGINE COMMERCIAL, or is my commercial rating good just like my INSTRUMENT rating?

Hi Kelly. Thanks for your question.

Well, I hate to be the bearer of bad news but yes, you will need to take another checkride in order to exercise commercial priviledges in a single-engine airplane (such as flight instruction). Currently with your certificate, you can only exercise commercial privileges in a airplane multi-engine land (AMEL). My certificate has a similar limitation. I have an ATP for AMEL but only commercial priviledges for ASEL. That means, I cannot act as a pilot in command in a single engine land airplane that required the operating privileges of a airline transport pilot certificate (such as an air carrier).

So of course the next question is, “What will you need to demonstrate to the examiner on the practical test?”

The official reference to this question is the FAA Commercial Pilot Practical Test Standards. If you open this document you will notice on page 1-v the “Additional Rating Task Table”, a copy of which I have included below. You can reference this table to see which areas of operations and tasks will be required to be completed on your checkride:

This table describes exactly what maneuvers have to be covered on your practical test by giving you roman numerals and letters that correspond to Areas of Operations and Tasks in the PTS. Here are the areas to be covered:

1. Performance and Limitations
2. Operations of Systems
3. Normal, Crosswind, Short and Soft Field Takeoff, Landings, Go-arounds
4. Steep Spirals, Chandelles and Lazy Eights
5. Eights on Pylons
6. Emergency Approach and Landings, System Malfunctions
7. After Landing, Securing and Parking

You’ll notice there are few thing you don’t have to, such as the stall series and steep turns but you still have to do the commercial maneuvers in a single engine airplane.

Let me know if you have any questions and as always…

Fly Safe!

This question comes from Karl:

I’m thinking about buying a retractable gear aircraft with 250 HP engine from a CFI who lost his medical. I am certified in high perfomrance AC (C-182) but I only have under 2 hrs of retract time.

I’m interested in taking a flight in the AC and he tells me that since I have a current medical and rating in a high performance AC, that I could be the legal PIC, even though I am not checked out in this plane. He would fly along with me, of course.

This doesn’t seem right to me. What do you think?

Hi Karl.  Thanks for your question. There are a few things that you need to think about here 1) Legality and 2) Insurance and 3) Safety.

Legality

According to FAR 61.31paragraph f, in order to act as a pilot in command of an aircraft which has an engine of more than 200 horsepower you must have received and logged ground and flight training from an instructor AND you must have an high performance endorsement from that instructor in your logbook.  In addition, if you want to be pilot in command of a complex aircraft, FAR 61.31(e) says that you must also have ground AND flight training in complex airplanes with logbook endorsement.  And just as a reminder, a complex aircraft has flaps, retractable gear and a controllable pitch propeller.  So that means if the airplane you are wanting to buy is a complex, high performance airplane you need 2 separate logbook endorsements (not ratings).  As a side note, these endorsements are one time events.

Insurance

Every insurance company and policy is different.  I would recommend checking with the policy on the aircraft to make sure you meet the open pilot provisions.  It might require you to have so much time in the make and model or it may require a proficiency check in the make and model by an authorized instructor.  Like I said, every policy is different.  It is best to call and talk with the insurance company or broker if you have any questions about your policy.

Safety

If you feel uncomfortable flying this airplane with this other pilot, don’t do it, even if is “legal”. Find a pilot or instructor who meets all the provisions above PLUS someone you feel comfortable flying with.  There are countless stories of pilots getting themselves killed flying unfamiliar aircraft.  In case you missed it,  here is my personal story of flying a unfamiliar airplane.

Hope this helps.  Let me know what you decide to do and if you buy it.

Fly Safe (and legal)

How many times have you said that to yourself?

Last night was one of those nights. There was an amazing strong thunderstorm that passed through Chicago last night around 7:30 P.M. Right after it passed through, there was an amazing scene that I feel fortunate enough to witness. Picture this…dark clouds on the right, orange sky on the left, double rainbow in the middle, the airport lights on full bright, and propagating lightning surrounding the whole scene. (that’s where the lightning appears to crawl through the sky). Yeah, words definitely don’t do it justice. It was simply amazing. And all I could think of, was “Man, I wish I had my camera!”

So for today’s trip, I bring my camera. And lucky enough for me, there was this beautiful turbine converted DC3 sitting on the ramp. Of course, my camera memory card was almost confiscated during an ugly incident with a customs official that was clearing this aircraft but that is a different story….so enjoy the photo because I went through a lot to get it.

I think my camera is now officially part of my flight kit. Fly Safe.

AOPA recently released a video that contains the audio and video showing the radar on March 21 when on March 21, 2008 a F16 pilot apparently tried to successfully scare the absolute living daylights out of two general aviation pilots flying a Pilatus PC-12 and a Beechcraft Premier. Both aircraft were equipped with a TCAS II system which alerts the pilots and if necessary, provides the pilots with TAs (Traffic Advisories) and if necessary, RAs, or Resolution Advisories. If you have never had the privilege of hearing these sounds, I have provided a sample of what a TA and RA sounds like:

Traffic Advisory

Audio clip: Adobe Flash Player (version 9 or above) is required to play this audio clip. Download the latest version here. You also need to have JavaScript enabled in your browser.

Resolution Advisory

Audio clip: Adobe Flash Player (version 9 or above) is required to play this audio clip. Download the latest version here. You also need to have JavaScript enabled in your browser.

So the question is, which one takes precedence? A Resolution advisory or an ATC clearance?

According to FAR 91.123:

When an ATC clearance has been obtained, no pilot in command may deviate from that clearance unless an amended clearance is obtained, an emergency exists, or the deviation is in response to a traffic alert and collision avoidance system resolution advisory.

Another question? Is it ok to fly through a MOA? Let’s take a look at our AIM 3-4-5. It says:

Pilots operating under VFR should exercise extreme caution while flying within a MOA when military activity is being conducted.

Another interesting point about this chapter in the AIM concerning MOAs. Did you know that the military aircraft operating in a MOA can be exempt from at least two rules 1) Aerobatic Flight and 2) Speed *they can operate above 250 knots below 10,000 feet* So, although it might be LEGAL to operate in a MOA, doesn’t sound like a real bright idea.

I uploaded the video to my youtube channel (http://www.youtube.com/askacfi) but you can’t watch it here too. (thanks to AOPA for the video)

Fly Safe (especially in a MOA)

This question comes from David:

Hi, I am a medical student and I wish to become a pilot after I finish my college. I am considering to go to a flight school in the U.S. but am confused about chosing the best one since I am overseas. Hope to hear from you soon.

David, thanks for your question. This question actually prompted me to start a whole new project (more on that below) so I appreciate it!

To answer the question, “What is the best flight school?”, is about the same as asking, “What is the best airplane to fly?” A hard question to answer unless you know the mission. Every person has an individual need when choosing a flight school and there is not one easy answer for that question.

There are many options when it comes to choosing a flight school.

• Do you want a college degree?
• Do I need preparation for a professional career?
• Do I need flexible hours?
• What kind of airplane do I eventually want to fly?
• Do I need bank financing?
• What kind of airplane do I want to train in?
• Do you want or need a accelerated flight school program or would you like a smaller flight school?

In order to give you a recommendation I really need to know more information about your goals once you become a certified pilot. Not knowing this information, it is hard to give you a blank recommendation.

However, I will say that I would recommend a flight school that is governed by FAR Part 141. Part 141 refers to the federal regulations under which the school operates. I generally recommend a Part 141 flight school for international students because they are usually better prepared to deal with the security requirements to train students from foreign countries.

I have a couple of sites that I would encourage you to visit:

AOPA: How to Choose a Flight School

AvScholars: Learn how to choose a flight school

Flight School Reviewer

Now, my new project (work in progress…just started yesterday):

Aviation School Review.com

Basically offering similar services as Flight School Reviewer but with some added features such as a map where you can see where the flight schools are located, which can be important. You can then click the map marker, look at information about the flight school such as aircraft available, certificates given and then read the reviews. Like I said, work in progress. I would love it if you tried it out and let me know what features you would like to have added.

If you can give me some more information about your requirements for learning to fly, I might be able to better answer your question.

Fly (and train) Safe!

I don’t know why, but I have noticed a lot of songs lately on the radio talk about flying private jets. That got me to do some research about airplane songs. Airplanes are featured in a LOT of songs! I found this great post at “Dictatorship of the Air” that suggested 10 songs about airplanes. I took those songs, some of the ones suggested in the comments of that post, plus some of my own favorites and created a iMix for iTunes. I simply entitled my mix “Airplane Songs” Here is my iMix. What do you think? What songs would you like to add or remove?

Before you even get started reviewing this mix, I have to defend the first selection. The reason it was added is because in the chorus he sings about leaving with a girl on his “G-V”. Maybe this mix will make a great soundtrack as you are driving to the airport for your flight lessons or work. Enjoy.