MT prop etc

by Richard Sims in 912 / 914 Technical Questions 5 years ago

Hi Folks, thank you for adding me to the group. I have a Dyn Aero Sportster with a 912ULS, MT7-A prop and a P-120U controller.

so here goes! On preflight check, the controller as I understand it is set to auto, then engine rpm idle plus 200, ie around 1600 engine rpm. You then select the rpm dial and place to minimum around 1400 prop, RPM is supposed to drop and green light goes out select max rpm, white light goes outrpm increases green light on.....only it doesn’t. Also how do you know what the proprpm is without strobing it? Manifold pressure on shut down is ambient ie 30.5 inches 2035 mbs, on running up to 3500 rpm manifold pressure shows 13.5

any thoughts advice would be welcomed, Many thanks and a happy new year to all!

rich

Re: MT prop etc

by RotaxOwner Admin » 5 years ago

RotaxOwner Admin

59 1.59k 15.4k

Prop RPM will can be calculated from the engine RPM divided by the gear ratio... (2.43:1 if you have the 'standard' gearbox)

Thank you said by: Richard Sims

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Re: MT prop etc

by Bill Hertzel » 5 years ago

Bill Hertzel

13 1.95k 7.98k

This is an MT-P-120U controller issue and the problem should be referred to the MT Factory or dealer.

Do you have the M-120 Manual?

https://www.mt-propeller.com/pdf/manuals/e-118.pdf

The P-120U has a Green Light and a YELLOW light. No WHITE Light.

The GREEN Light indicates the prop is in the Full FINE position. (Max RPM)

The YELLOW LIGHT Indicates a Fault.

Please restate your problem clearly and what it does and does not do.

Maybe we can help.

As the Admin Stated, Prop RPM is Engine RPM / 2.43.

1400 Engine = 575 Prop.

1600 = 660

2000 = 825

3400 =1400

5600 = 2300

5800 = 2385

Bill Hertzel
Rotax 912is
North Ridgeville, OH, USA
Clicking the "Thank You" is Always Appreciated by Everyone.

Thank you said by: RotaxOwner Admin

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Re: MT prop etc

by Richard Sims » 5 years ago

Richard Sims

1 1 5

Hi Bill,

thank you for your message. I ll have another go and see the results!

A happy new year to you,

Rich

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MT prop etc

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