Saturday, October 9, 2010

More 402

Well the wet season is coming stronger and stronger. I have now had to do a few ILS's into Darwin on the return leg from a days flying. The weather is usually ok up until the mid afternoon and then it turns sour. I'm not 100% what a microburst is, but i assume there have been a few near the field with the windsock literally swinging around in direction every few minutes, up to 25kts from east to west and north to south. Made for one or two hairy approaches on the edge of the storm. However 4km of runway and the C402 doesn't pose me a huge problem, even with a 25kt tailwind. Having said that, when you are turning a 2nm final over the field and you can feel yourself being dragged towards the strip sideways in the base turn, it's definately not a procedure i want to practise regularly.

I'm feeling a lot more confident now in the C402, with fuel figures and understanding the aeroplane. I find the hardest part is all the conversations, which is really a recipe to fail unless you are diligent in your calculations. What i'm trying to say is constantly converting between litres, kilo's and pounds can lead to the wrong figures in the paperwork, wrong weights for max payload take-offs, and the wrong amount of fuel being loaded. We use pounds in the flight plan, and also the planes fuel gauges are all in pounds. This is easy to use as the plane burns roughly 100lbs per engine per hour. So if each tank is showing 300lbs, as a rule of thumb you know you have 3 hours of fuel, and around 2.4 hours till you will hit your fixed reserves. Now we have to convert the pounds to litres for the refuellers. This is done by dividing the pounds of fuel by 1.58 for avgas. We then use kilo's for the weight and balance, so pounds divided by 2.204 gives you the weight in kilos. Again, its not hard or challenging, you just have to think about which conversion you are attemping and make sure you do it in the correct order.

As a rule of thumb in regards to fuel, the boys always substract 50lbs off the final fuel figure (we call it our 'gravy'). So basically whatever fuel figure you are using from the previous paperwork, you know there is roughly 30 litres of extra fuel in the tanks. When available (depending on the job) we also use a 10% extra policy, on top fixed reserve, flight fuel, variable reserves (15% of the flight fuel) and plus whatever holding is needed. This ensures adequate fuel, as even though our planning is around 200lbs per hour, it ends up being roughly 230lbs with take-off, climb segments included.

I have been flying the C402C a lot more as well. Definately a much nicer plane to fly. Significant improvements are the vortex generaters which allow greater lift and payload. They also have 50 more horses on take-off, and the turbos boost the engines to 39" of manifold pressure, whereas the B model only goes to 34'5" of manifold pressure. So the take-off performance is a lot better. The wing also looks better without the tip-tank, and best of all is the tank-to-engine fuel systems. No need to change tanks unless you are crossfeeding to balance the tanks. It also holds about 200lbs more than the B model, total fuel being 1236lbs, roughly 785 litres of fuel, for those of you using the metric system.

Other nice features on the C model is the weather radar. They are probably from the stoneage of aviation, but still when flying in the soup with weather around, it gives you are better informed idea of where the significant weather is so you can avoid it. It's definately not great, or even colour, but its better than having no radar!

Till next time, thanks for reading.

1 comment:

  1. Wow, I really loved this post! It's so interesting to see the real details down to the weight and balance and the conversion factors. Good work!