Cessna 206 Advice

[IL VATE]

Hi Guys

I need an advice from anyone with more experience on 206 or constant speed prop.
I operate in a place where I cant get other advices.
A 206 40 years hold with a new engine fitted, during t/ o cant get more than 2200 rpm everithing forward, at see level and 20 deg oat.
Maintenence said no problem, but they cant state that is the gauge that underread.
In the climb out after t/o the ROC reads 700' but the prop is still fully frw and it cant be decreased, straight and level performance looks ok, but still with prop fully frw.
Please any idea is welcome.

[Tarq57]

A 206 should redline at 2700, or 2850rpm (max 5 minutes) depending on the version of the engine.
The sound difference alone between 2200 and 2700 or 2850 would be extremely noticeable, to anyone familiar with the sound of 6 cylinder piston engines. Not to any great accuracy, but should be enough to get an idea whether it is the rpm gauge or not.
Is this 700fpm at all up weight, or light? If light, it sounds like well under full power is produced. If MAUW, 700FPM is a bit low on performance, but within the expected range for an old a/c.
I would suspect the governor needs attention.

When you say "prop is still fully frw and it cant be decreased" do you mean you don't want to decrease it because the performance is ****e, or that if you try to change it nothing happens?

[toolowtoofast]

If it is Conti O520 powered, it should get 2750/2800rpm and around 27-28" at full power. 2200 is the bottom of the green range for this configuration. The O550 should get these number too.

If it is O470 powered (unusual but possible) it will only go to 2400-2450, but it should still achieve that static.

It's not so much the RPM, but the MAP that you're getting at 2200 - what numbers are you getting? Is it 2 or 3 blades?

And @ MAUW 700fpm is about as good as you'll get.

[IL VATE]

Hi guys
The engine is the 0520 and the Map at full pwr reads 28".
Last flight , when I noticed the low rpm, it was just two of us with full fuel, far from Mauw.The prop is two bladed.
When I say the RPM can't be reduced i mean that is already at cruise setting.
Thank you!!!!

[Tarq57]

Yep, sounds very much like the governor needs attention.
I've flown a similar age model U206, with a two blade prop, and at MAUW she climbed at about 800fpm, 25squared.
SL, about 15C.

As an aside, it could be damaging to the engine to run it at this low rpm and a comparatively high MP. Make sure you keep it fairly rich, maybe full rich, if you absolutely have to fly in this condition, as long as the MP is significantly above about 24" (if I remember correctly.These figures are guesses only.)
The POH (if present) should offer correct guidance as to permitted rpm/MP/mixture-fuel flow combinations.

[Tarq57]

PS: "0-520", or I0-520 ?
Another question.
When you run it up, and test the CSU, how much MP does it take to achieve 1800RPM?
And (roughly) how far does the prop control move back before the RPM starts to drop? Should need about a 5cm movement, this is rather subjective, but if the RPM was to start dropping almost immediately on starting to move the knob back, it would suggest an adjustment or cable problem.
If the MP required to get the engine to 1800 is higher than about 22, that suggests that the prop may be the wrong type for the aircraft.
What is the prop type/number?

[IL VATE]

The propeller is
E2A34C73-Q
Blade S90AT-8

[Tarq57]

Well, that appears to be the correct prop/blade for the aircraft.

[heated ice detector]

I Think you may find the tacho is under reading, does your workshop have access to a tacho tester, not unusual for them to be that much out, there is also a fuel return check valve which i have seen installed back to front, it can also cause power problems.
max static rpm is normally around 50 rpm below red line

[IL VATE]

we got to 2500 rpm now fixing the cable...stin needs a bit more.
But now there is the fuel flowthat doesnt match.Thank you for now.