I just got back from a week of leave. Not only was yesterday my first flight back at work, but it was in a completely new plane my company has bought. Still a Cessna 404, but it was bought from the East-Coast of Australia. For this reason it has been fitted with a lot of extra kit, such as de-icing boots (possibly just warmers though - I wasn't sure if they were boots or just pads that warm the wings. It also had these pads on the tail, and props too!) These add to the empty-weight and also affecting its performance, in terms of climb and speed.
It is pretty rare in the top-end to find planes with these sorts of mods as they are not needed, add a lot of extra weight and as i said affect the performance of the plane. So it was a first for me. The only difference inside with the extra gear was just a few extra switches, which i left in the OFF position!
The plane itself looks pretty good, with a nice new blue paint job. Semi looks like Japan Airlines tail with a big blue orb. I will take photos soon, but i keep forgetting my camera. The only thing i found really bad with this new aircraft was the GPS. It is the oldest Trimble i have seen or ever used. Most GPS only take a few seconds of fiddling to figure out the basics, or setting a route or flight plan. The rest can come later with exploration and fiddling. But i sat there for a solid 5 - 10 minutes doing run-ups before i remotely worked out how to get my destination in the screen! Was harder than flying the plane no doubt.
(For those who read this and are not in aviation - run ups refer to running the engines of piston planes before they fly for a few reasons. If someone wants to correct me or add to this feel free!)
But the main reason we run the engines up, is to first warm the engine and oil. Advancing a cold piston engine to take off power is pretty much a recipe for an engine failure with the rapid thermal change and cold oil trying to force itself around the engine. I usually taxi the plane to the run up bay in the morning and do my required paperwork sitting there while they idle to make sure the Temps and Pressures (T's and P's) are in the green operating range. Living in the tropics, the engines warm very quickly and usually remain quite warm. I haven't had to experience this is really cold weather!
In the Titan we then increase the engines to 1500RPM. The Cessna 400 series have a governer check, which i haven't done in any other piston plane. This involves pulling the pitch levers back to the feather detent. The RPM shouldn't change, however it is normal for the Titan engines to lose maybe 100 to 200RPM. Then when you move them past the feather detent, you test the feather of the aeroplane. A lot of places make you do this test 3 times..... I don't actually know why? However, its our company policy to just do it once of the 400 Series Cessna's, so thats what i do. As you do the check, you want to see changes in the oil pressure gauge and manifold pressure gauges too.
Once thats checked, and still at 1500RPM, i check the magnetos, so make sure there is no fouling of the plugs, and that the drops are within the limits specified in the flight manual. This is 150RPM max drop and 50RPM difference between the 2 engines. Usually this is all in limits. If its really rough, then i will clear the engine, by running it at a high RPM (sometimes near take-off power) with the mixtures leaned. This usually clears the foulling and lets them run smoothly. If it doesnt clear it, then its usually something else and maintenance is required most likely.
We then do the idle check - make sure the engines won't cut out? Im not 100% sure why we do this check. If im at low power on the ground and i think an engine will cut out, i put the low pressure pumps on. It usually cuts out due low fuel flow and a hot temperature. Especially if the plane has been heat soaked in the sun all day, the fuel vapourises before it reaches the engines. If this is the case you need to purge the fuel lines before starting, with high pressure pumps, throttles full and mixture at idle cut off.
After the checks are done, you can be satisfied that your plane is safe, as you have completed virtually everything on the pre-flight inspection and engines are run up and warm.
So after getting all this done, i finally worked out the GPS!
Interesting post Mike. Have to admit that I've always just taken the idle check at face value (ie. does the engine hold its revs at idle? yes? then... good!) rather than really thinking about why it might happen. The fuel vapour issue is an interesting one - I assume this is only really the case with higher performance aircraft?
ReplyDeleteLove the photo at the top of your blog, by the way. That's what flying's all about!
Hey!
ReplyDeleteYeh i dont know what the idle check is for really either. In runups it never cuts out, or hasn't yet, but i have had an engine die on me after landing at least 3 times. In singles and twins.
Basically once you get to high level cessna's its all continental engines, the 520 models. all the pipers etc use lycoming 540's usually. Both are rated to 300HP (from memory anyway, i think the continental may be 285 normally aspirated.) Being fuel injected, hot days, low fuel flow and pressure, means they will cut out. I have taxiied off a runway with one engine dying on me the moment we cleared! lucky it was at night and managed to start it with only one passenger noticing. They tend to get nervous when it dies, and you have to explain why it happened.. usually because i turned the pump off prematurely, or in the 210 you dont use the pump, and in the baron, only if its above 32 degrees celcius. In the 402 you turn the low pumps on for descent and landing and take off. In the titan its meant to be the same, but no one uses them in the titan, which is easier to explain in words than it is to write, so i'll leave that one.
Hope that helps.