Ops performance question

[heli2o]

Hello fellow flyers.

Just wondering how accurate the conversion rates are required in the actual CPL exam. For example I'm doing a practice test from the aft notes and am required to convert 367L. Using the ERSA conversion table its x by 0.8. AFT notes use x by 0.815. So overall there is a difference of 5.5kg.

So in the CASA exam do I need to remember it by 0.815 or is the ERSA conversion acceptable?

Tips or help on this one would be appreciated (and any other tips for the subject).

H2o

[SpecialGray]

I'd use the ERSA figures as those are the ones you are allowed to take in with you. I think the idea of AFT ones were to show you how rounding errors can contribute to an erroneous figure.

In the exam, quite often you don't have a chance to enter an exact figure as you do in the AFT practice questions, rather you pick the 'best' answer from the A, B, C, D list.

TIP: Sometimes the figure you calculate will come so closely to the 'best' answers given, you'll need to do an additional calculation to figure out the difference (e.g., you come up with a figure after your calculations of 458 something, the answers give 424, 493, 678 and 145. So you also have to work out which figure of 424 or 493 is closest to your figure of 458 to get the mark).

[Zabar]

Accuracy is essential in this exam. The most accurate and therefore correct conversion figures to use come from the Bell 206-L extract. In the fuel loading table you'll see that they use 0.81 kilograms per litre. Mark up your ERSA conversions table for Jet-A , in pencil, with the following figures: litres to kgs = 0.81, kgs to lbs = 2.2046, Imp Gals to lbs = 8.1, US Gals to lbs = 6.8. Always travel through one of the new values when doing a conversion.

My other tips are: round all your calculations to 3 decimal places. Do all your W&B calculations in lbs and inches. Convert any Kg values to lbs first. Convert answers in inches to millimetres at the end if required for the answer.

It's even worth practicing using the same calculator as ASL provide to help prevent any silly keying errors. I know at least one guy who failed the exam most likely he thought, due to this. A $25 calculator is cheaper than a re-sit.

Good luck

[widewindsidewinder]

Hey mate,

0.815 is the go, especially as the extract uses .081 as a conversion factor. Also, for pounds use 2.205, not just 2.2.
Additionally, with your ERSA conversion tables, do not go straight across from Litres to Pounds as that will give you a vastly different answer, and as Ops is all about being right on it, you don't want that!
Basically, the rule is, whenever you're converting from Litres to Pounds, or Pounds to Litres, you MUST go through Kilograms first.

Par example:
Jet A1 Litres to Pounds
100L = 100 x 0.815 = 81.5 kg
81.5kg x 2.205 = 179.7075 lb (say .71)

And vice versa.
You diggin'? Hope all goes well mate, you'll be fine, just practice the living piss out of those W&Bs so you can do them with your eyes closed.
PS - Get really comfy with Long Range Cruise Fuel Flows, there are a few in there on them!

[heli2o]

Thanks everyone for the replies. Probably best I use the extra decimal places to be on the safe side.

[RotorBez]

Absolutely use 0.815 I found that the ERSA units were good for calculations but weren't always great when it came to selecting the "Correct" answer from those provided as there wasn't one that matched exactly!

If it helps, I very recently passed this exam and I used 0.815 and a couple of other more accurate conversions compared to what the ERSA or indeed AFT notes articulate.

Wouldn't it be great if the testing authority actually advised what units to use....rather than having a number of close but not consistent units of measure.

Whinge over - sorry.

Good luck.

RotorBez