Questions if you are bored

[safepilot24]

Some more questions from a thankful but starving CFI:

1.) Suppose you are flying a 2000 C-172 Skyhawk that has a red beacon on the vertical tail, and a white strobe light on each wingtip, and the beacon is inop...can you still fly day VFR as per 91.205? Reg states that for small civil aircraft, certificated after 1996, that's me, aircraft must have operable, "approved aviation red or aviation white anticollision light system."

Do my white strobes count as an "approved aviation white anticollision light system?"

What about 1979 C-172's that have red flashing beacons but no strobes. I want to be legal, but display some common sense towards collision avoidance as well.

2.) Which is worse and why....Skidding spins or slipping spins? (Seems to be the hottest question on the CFI checkride right now)

3.) For C-172 Skyhawk, the PIM specifies to "increase distances 10% for each 10 degrees above standard temperature." Can I take this to be a linear relationship between performance values and temperature? (i.e, if temperature is 7 degrees above standard, increase distances 7%?)

4.) Calibrated airspeed question: CAS is IAS corrected for instrument and position errors. If you look in the C-172 PIM, there is an airspeed calibration chart that shows the following:

KIAS 40 50 60 70 80 90 100 110 120
KCAS 49 55 62 70 80 89 99 108 118

The way I interpret this is at high angle of attacks, the pitot tube is not collecting the same total pressure since it is meeting the relative wind at an angle. Calibrated and indicated are the same at 70-80 since these are critical approach speeds, and calibrated is actually slightly less at high speeds because the faster moving air across the static port experiences a significant pressure drop which makes it seem like less static pressure, thereby making the pressure difference appear to be greater. Am I correct in my assumptions? I just want to make sure I understand the "instrument and position" errors the definition is referring to. Any other position or instrument errors I should know about other than slips?

5.) Most light GA aircraft are equipped with 2-12 volt batteries connected in series. Are these considered 35 amp-hours, meaning will they run 35 amps for one hour or 70 amps for half of an hour? I am trying to gain a better understanding of how much I can run off the bat in case of alternator failure?


Thanks everyone.

 

[safepilot24]

These are good questions...I can't believe no one has a response?

 

[Singlecoil]

Some more questions from a thankful but starving CFI:

1.)Do my white strobes count as an "approved aviation white anticollision light system?"

Yes.

What about 1979 C-172's that have red flashing beacons but no strobes. I want to be legal, but display some common sense towards collision avoidance as well.

They count too. If you have the red tail beacon and the strobes, then consider it redundancy.

2.) Which is worse and why....Skidding spins or slipping spins? (Seems to be the hottest question on the CFI checkride right now)

I don't know. Do you mean entering the spin from a slip or a skid?

3.) For C-172 Skyhawk, the PIM specifies to "increase distances 10% for each 10 degrees above standard temperature." Can I take this to be a linear relationship between performance values and temperature? (i.e, if temperature is 7 degrees above standard, increase distances 7%?)

Yes, it is linear, you can interpolate.

4.) Calibrated airspeed question: CAS is IAS corrected for instrument and position errors. If you look in the C-172 PIM, there is an airspeed calibration chart that shows the following:

KIAS 40 50 60 70 80 90 100 110 120
KCAS 49 55 62 70 80 89 99 108 118

The way I interpret this is at high angle of attacks, the pitot tube is not collecting the same total pressure since it is meeting the relative wind at an angle. Calibrated and indicated are the same at 70-80 since these are critical approach speeds, and calibrated is actually slightly less at high speeds because the faster moving air across the static port experiences a significant pressure drop which makes it seem like less static pressure, thereby making the pressure difference appear to be greater. Am I correct in my assumptions? I just want to make sure I understand the "instrument and position" errors the definition is referring to. Any other position or instrument errors I should know about other than slips?

You are correct, due to the installation of the pitot tube, it won't be accurate at all angles of attack. Generally they rig it to be the most accurate at approach speeds, as they are the most critical. I've never heard your idea about a "significant" pressure drop from air moving over the static ports, but you might be right. I wouldn't classify a 2 knot difference as significant, however.

5.) Most light GA aircraft are equipped with 2-12 volt batteries connected in series. Are these considered 35 amp-hours, meaning will they run 35 amps for one hour or 70 amps for half of an hour? I am trying to gain a better understanding of how much I can run off the bat in case of alternator failure?

Voltage and amps are two different animals. If you have a 35 ampere-hour battery, then your statements are correct in that it will give you 70 amps for 1/2 hour or 35 for one hour. Connecting 2 12 volt batteries in series will yield 24 volts, but how many amps that is depends on how big the batteries are.

 

[Mickey]

1. No! If either your beacon or any of the strobes are inop you cannot operate day VFR except to fly to a location to have it repaired. 91.205(b)(11) ...In the event of failure of any light of the anticollision light system, operation of the aircraft may continue to a location where repairs or replacement can be made.
I think the beacon would fall into the 'any light' category.


5.Your understanding of amp hours is correct
Putting two like batteries (or cells) in series will double the voltage but the amperage will stay the same. Putting two like batteries (or cells) in parallel will double the amperage but the voltage will stay the same.


Take care.

 

[groundpointsix]

1. No! If either your beacon or any of the strobes are inop you cannot operate day VFR except to fly to a location to have it repaired. 91.205(b)(11) ...In the event of failure of any light of the anticollision light system, operation of the aircraft may continue to a location where repairs or replacement can be made.
I think the beacon would fall into the 'any light' category.

I believe that the strobes and the anti-collision lights are considered two seperate systems. If you read 91.205(b)(11) again, you will see that it says you must have "an approved aviation red OR aviation white anticollision system." Therefore, if your strobe (or your beacon) fails and you still have the other system operating, you're legal. Now, if you're flying an older 172 that had the strobes installed aftermarket and wired to the same switch as the beacon, it might be a different story under certain circumstances (i.e. a short circuit), but a burned out bulb in one light shouldn't make you illegal. That's what I was taught from the beginning-- that I needed one or the other, but not both. If someone has a legal decision saying otherwise though, I'd love to see it posted, especially since I just made a flight with inop strobes this morning.

 

[safepilot24]

The way I understand it is that the anticollision light system means either beacon or strobes. Since the regs do not specify "beacon" or "strobes," if my beacon became inop my strobes make me legal. Perfect example is Archers and Mooneys do not have beacons. I think this is a reasonable way to look at it. But listen to me rambling about beacons when we are on the brink of war...!
B

 

[Kream926]

i believe stobes count as an ati-collision lighting....im pretty sure you van use strobes if the becon is inop or not installed..

safepilot24 i belive as a CFI you should know these things..if one of your students asks and you dont know the answer your not doing your job

 

[avbug]

Most light general avaition airplanes don't have two batteries. The 35 amp-hour battery should (in theory) deliver 35 amps continuously for one hour, or one amp for 35 hours, etc. This applies to a new, fully charged battery with specific gravity in the designated range for the fluid temperature.

Which is worse, a slipping or skidding spin? Think about that for a minute...think about the spin, the aerodynamics and forces involved (speaking in general terms here), and the recovery.

Can you have a slipping or a skidding spin? Remember that a spin is a rolling and yawing motion, and frequently a pitching motion, coupled, but not linear in their relationships. Think about the relationship, and you'll realize it's a "trick" question.

Entries are another matter, and I suspect the person doing the asking is one who subscribes to the cross-controlled-stalls-are-evil school of thought. It's a fallacious school of thought, but a popular one. It's borne of too little cross-controlled training...ask the question here, and you'll find that a good number of responses will probably be that you should never do a cross controlled stall...mainly by those who are missing some very basic flight training and skills.

People are getting asked this on their practical test?

 

[Iceman21]

I have flown with the beacon inop during a night flight, I inquired about it, looked up the exact reg and talked to our chief instructor. The beacon was placarded and the strobes were working just fine.

LEGAL!!!

I would love for an expanded discussion on the spin theory avbug mentioned. Would you oblige?

 

[172driver]

The spin itself will be no different once developed. However, the slipping entry (cross-controlled) is a bit more aggressive as the high wing will stall first and drop all the way through. A little surprising the first time you perform it but no more dangerous at altitude than a skidding entry.

 

[stardog]

As a followup to the slipping entry to spin posted above, this is what I was able to deduce. In a slipping entry, the high wing will have the aileron down increasing it's angle of attack, thereby aggravating the stall. Similarly, the rudder use in a slip will cause the airplane to yaw into the high wing. This reduces the wing's speed through the air, further aggravating the stall on that wing.

 

[Deftone45075]

I believe that the strobes and the anti-collision lights are considered two seperate systems. If you read 91.205(b)(11) again, you will see that it says you must have "an approved aviation red OR aviation white anticollision system." Therefore, if your strobe (or your beacon) fails and you still have the other system operating, you're legal.

The way I understand it is that the anticollision light system means either beacon or strobes. Since the regs do not specify "beacon" or "strobes," if my beacon became inop my strobes make me legal.

According to the reg., no your not legal. Your right that either strobes, or the beacon are an anti collision light system, however if your beacon fails. It is still a "failed" anti collision light. And 91.205 say that if ANY of the lights fail, you may only fly to a point where repairs can be made.

Just because the strobes add redundancy doesn't mean you can fly with the inop. beacon. It is installed and falls under the minimum required equipment as per the above reg. If any of those items are inop., the airplane is not legal, unless you have a MEL to defer the item.

 

[lucky2Bflyin]

Reg says "approved red OR white anticollision light system." If my RED rotating beacon is inoperative prior to flight, and I had an operating WHITE anticollision light system, such as the strobes, you had better believe that I am going to fly. Personally, I think it is for this reason that the FAA decided not to use the words, "beacon" or "strobe." Once again, I think common sense dictates this question. The purpose of the "anticollision light system" is to rapidly alert other people, aircraft, etc of an aircraft starting up, operating on the ground, or in the air. From personal experience, I have discovered 2 beacons inop prior to flight with students. I like these occurences because they provide a "real-life" application of the regs. Neither time did we ground the airplane.

Hope that helps.

 

[Deftone45075]

It says red OR white because you are allowed either. If your aiplane only has a beacon and no strobes, the "red OR white" covers you. If you have strobes without a beacon, the same reg covers you. That is where the "OR" comes in.

If both are installed, they TOGETHER form the anti-collision light system. If your beacon is inop. it is STILL a failed component, and you cannot fly except to a place where repairs can be made.

I like these occurences because they provide a "real-life" application of the regs. Neither time did we ground the airplane.

Well, if something is installed in the airplane, it mustbe operative to be airworthy. If you have an MEL that says you can defer the light, than you can go. Otherwise your teaching a "real life application of the regs" incorrectly to your students.

 

[lucky2Bflyin]

From 91.205:

"In the event of failure of ANY light of the anticollision light system..."
Deftone, I can see your point and it is a good one based on the way the reg is worded. Personally, it just does not make sense to me why you must ground the airplane if you have operating strobes, but your beacon is inop or vice versa? Think about it this way. Suppose your beacon IS working, but your strobes are not....does this mean you must ground the airplane?

There is no logic to this at all since neither strobe nor beacon is a required item on the type certificate data sheet. I am fully aware that when consulting 91.213(d) for inop equipment that you must refer to 91.205, but where is the logic here? (Maybe that's my mistake is trying to search for logic in a goverment document???)

My last point regarding "ANY light of the anticollision light system." Suppose your aircraft has two strobe lights, one on each wing (typical if you are flying a new C-172), and ONE of the two lights becomes inop. To me, the way the reg states you could not fly based on this situation as well?

Deftone, I am all for following the regs as strictly as possible, but the reasoning behind this one just does not follow...anyone agree with me?

P.S.....I propose those members who post more than 100 on the FAR discussion should qualify for an aviation law degree....can we just make this policy?!!!

BEB

 

[cocknbull]

I'm looking at the equipment list for a 2000 C172R and they do not list either the storbe or the beacon as required. They list it as "S" or standard. According to their list this means it was not required by FAR or FAA certification. Interesting..... Since we all know 91.205 and we can see according to that reg. that it is required. I don't know what to tell you. Typically when dealing with inop equipment you would use a flow..

Required by type certification on equipment lists?

Required by AD?

Required by 91.205?

If yes you can't fly. If No, you can fly however it must be deactivated and placarded or removed and a new weight and baklance be made.

In this case I would say Fly day VFR only. According to Cessna's Operating hand book the aircraft was not required by certification to have an operable collision light system. Infact after reading the manual the aircraft was more then likely typed before March 1996. The manuals first edition came out in December of 1996.

 

[Mickey]

We have two white position lights on the tail of The ERJ. If either one of them is out we cannot fly at night. Regs are regs and this is a real life application. (yes, I know this is not an anti-collision light but, I just brought it up because it's amazing how a little light can ground an aircraft). I think the focus here for discussion should turn turn to the date of certification and what the feds are referring to.
Take care.

 

[501261]

I might have some insight on the Beacon vs. strobe debate. A couple of years back an airplane I was flying had 3 strobes (wingtips and tail) and 2 beacons (upper and lower). During a preflight at an outstation I realized that the upper beacon had burnt out. I went to MEL it when a friendly Fed came up to do a ramp check (he actually was very friendly and gave us a ferry permit to bring us home).

To make a long story short, we couldn't MEL the beacon because in the airplane equipment list the beacon is labeled the Anti-collision lighting system. As we know by now the "anti-collision lighting system" is required by 91.205 and can not be MEL'd.

In conclusion beacons and strobes are both acceptable anti collision lighting systems, which is why you see airplanes with one and not the other. However, 1 of them has to be considered the "anti-collision" lighting system in the POH or equipment list. In our case the beacon is considered the anti-collision (according to the MEL, equipment list, and switch label) and both beacons are required to be working for flight. Strobes are just other lights in our case, just like the recog and logo lights and are not required for flight.

 

[groundpointsix]

Also, maybe someone has looked this one up (not saying this is fact, but don't want to take the time to research it): Where does it say in the FAR's that if you have the collision light system installed that you have to have it turned on? I know it is implied, but is it mandatory?

FAR 91.209 (b): No person may operate an aircraft that is equipped with an anticollision light system, unless it has lighted anticollision lights. However, the anticollision lights need not be lighted when the pilot-in-command determines that, because of operating conditions, it would be in the interest of safety to turn the lights off.