November 16, 2011 at 2:16 pm #83610
When i appply full power for take off my MP both go slightly above redline (maybe an inch). Should i come back a little off full power or is this short time above redline normal/ok. This is for a RamVI C340. None of my instructors has ever mentioned it until a new guy the other day had me pull it back a little during takeoff roll. My Standard proceedure is usually to come back to top of the green upon reaching 1000ftAGL and cruise climb so im not over redline for long.November 16, 2011 at 2:35 pm #95187
I have a 340 and mine is set up where all levers are pushed to the stops (full power) the MP will get to Red Line year round.
I never need to do any adjustment in the summer, I push the levers to the stops and monitor to make sure both engines are making Full Power by the gauges. In the winter, I need to limit the MP on the TO roll to keep under Red Line.
When I say year round, here is what I mean. During the summers, it will make the Red Line during the max heat of the day, and that is about 85-90 F where I live. But in the winter, it will blow by the Red Line if the throttle is pushed to the stops so it is a manual adjustment to get to full power without over boosting.
I usually do not fly when it is colder than -15F on the ground, but when it is this cold, I am sure the MP would go high enough to exercise the pop off valves. I don’t know how much over Red Line MP it would go because I have never tried.
I had a Seneca before the 340. I did have after market waste gate controllers but it was up to the pilot to limit the MP manually all the time. So I became used to doing this and the habit continued.
So you can have the motors set up to get up to Red Line when the throttles are at the stops – but if you do this in the winter, you will need to re-set for summer or you will not get max MP at the stops.
I guess I am used to it now, I have mine set up for hot days in the summer and manage the max MP manually the rest of the year.
JimNovember 16, 2011 at 3:27 pm #95190pmcnameeParticipant
More MP, more fuel flow, more power. Call it a Ram VIII.
Fly it back to the airport and try another takeoff while it is warm. If it still over boosts have your mechanic adjust them back. A little over boost want hurt. RAM proves that everyday.November 20, 2011 at 8:20 pm #95210
Depending upon engine and air temperature, it is not uncommon for MP to go a bit over redline when throttles are pushed all the way up on the RAM engines. Pulling back the throttles to fix this is not a good idea.
At full throttle the engines are obtaining a lot of their cooling from fuel flow, and when you pull back the throttles even a bit, the fuel flow drops a lot. The engines are much more likely to be damaged by the excess heat derived from reducing that flow, than by an inch or two of additional MP.
Be careful about having the mechanic mess with the linkage or injection system to fix this. Unless it occurs all the time, in all temperature conditions, and is well over an inch or two, you might find that after it is ‘fixed’, under cerrtain temperature conditions, you do not get power up to redline MP, regardless of throttle setting. Not a good thing.
Kevin E. Ware, ATP, CFI MEII
RSTOL, RAM VII, C340ANovember 21, 2011 at 9:43 pm #95213
Thanks all. Sounds like its pretty normal and just another thing to keep an eye on 🙂November 24, 2011 at 9:49 pm #95226rwelshParticipant
As the others have said don’t get your skivvies in a ball over and extra inch of MP. Worry more about having lots of fuel flow at takeoff power; at least 38 GPH for the RAM VI.
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