Thread: Few elemantary questions
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Old 06-12-2007 | 08:44 PM
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oldveedubs
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From: pǝʇɹǝʌuı
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-On a newer Cessnas with Fuel injection versus older with Carb, why is it that you start the engine with mixture "out" on fuel injected versus mixture"in(rich) on carb equipped Cessna? Also, why is there primer on older cessnas but not recent ones?

Since they are fuel injected the mixture control directly controls the fuel going into the cylinders. By controlling fuel flow to the injectors it regulates the air/fuel ratio. Mixture out keeps the engine from being flooded during the 3-5 seconds you may be cranking.

On carb equipped airplanes the mixture controls the amount of fuel entering the carb. Usually when you start carb equipped airplanes you will see some black smoke because the mixture is initially too rich. With fuel injected you want to avoid starting with full rich because there is a tendency to vapor lock causing a longer cranking time with the possibility of at least some of the cylinders being flooded.

When you use the primer on an older cessna you are injecting raw fuel into the cylinder. When you prime fuel injected airplanes you go mixture idle cut off, fuel pump on, mixture full rich for a combination of either several seconds or a fuel flow indication, mixture idle cut off. By going full rich on the mixture you are effectively squirting raw fuel into the engine on a fuel injected airplane similar to that of a primer on an older carb equipped airplane.

-I notice some airport that has both ATIS and AWOS. What is the purpose of having both?
Usually AWOS updates minutely while ATIS is hourly disregarding any special reports. If you want to go flying during a marginal day and the ATIS is 30 mins old...call up the AWOS and see what is current. The phone number can be found in the AF/D.

The ATIS is referenced from an ASOS/AWOS station and the only significant difference is that the winds are magnetic...the ONLY weather source that has winds magnetic.

-Aircraft with mode C transponder calls tower/ground with letter "A" after aircraft type when making initial contact. I recall there being more several more letters designating different equipment on ACFT. Where can I find this index/info?
Flight Plan Box 3
No DME
/X No transponder
/T Transponder with no Mode C
/U Transponder with Mode C

DME
/D No transponder
/B Transponder with no Mode C
/A Transponder with Mode C

TACAN only
/M No transponder
/N Transponder with no Mode C
/P Transponder with Mode C
Area navigation (RNAV with LORAN, VOR/DME, or INS)
/Y No transponder
/C Transponder with no Mode C
/I Transponder with Mode C

Advanced RNAV with transponder and Mode C
/E Flight Management System (FMS) with DME/DME and IRU positioning update
/F FMS with DME/DME position updating
/G Global Navigation Satellite System (GNSS)
/R Required Navigational Performance (RNP)

Reduced Vertical Separation Minimum (RVSM)
/J /E with RVSM
/K /F with RVSM
/L /G with RVSM
/Q /R with RVSM
/W RVSM
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