A-1 with MTV-15 prop... RPM??

[bertievdbunte]

Good day!

Since a week or so I am the proud owner of a '90 A-1 PH-PHX. I have a bannertowing company in the Netherlands since a year or 5 and used to fly with 2x PA-18's and a C172. Since then business has continued to grow and that's why I acquired the Husky, and also for towing the bigger sinds.

It has the MT prop STC with the MTV-15 prop installed on it. The RPM indicator has the red line on 2500 RPM, and the German prop manual also says that.

When I take off with prop lever forward and full MAP I get 2700 RPM. The TCDS of the prop also says max. 2700 RPM and the engine itself too.

So I am a bit confused what to do. Off course in a banner pickup I give full throttle, but it's not nice to see the RPM indicator go beyonds its redline.

Any advice appreciated!

Regards,
Bert

[mvivion]

Good day!

Since a week or so I am the proud owner of a '90 A-1 PH-PHX. I have a bannertowing company in the Netherlands since a year or 5 and used to fly with 2x PA-18's and a C172. Since then business has continued to grow and that's why I acquired the Husky, and also for towing the bigger sinds.

It has the MT prop STC with the MTV-15 prop installed on it. The RPM indicator has the red line on 2500 RPM, and the German prop manual also says that.

When I take off with prop lever forward and full MAP I get 2700 RPM. The TCDS of the prop also says max. 2700 RPM and the engine itself too.

So I am a bit confused what to do. Off course in a banner pickup I give full throttle, but it's not nice to see the RPM indicator go beyonds its redline.

Any advice appreciated!

Regards,
Bert

The 2500 rpm limit is a European limit for noise reduction. That prop works fine at 2700 and is approved there in US. In Germany at least, the restriction to 2500 is required. You’d have to verify if it applies in Netherlands.

Or, “Dont ask, don’t tell”. They pull hard at 2700..... If tach is marked 2500, who will know?

MTV

[bertievdbunte]

The 2500 rpm limit is a European limit for noise reduction. That prop works fine at 2700 and is approved there in US. In Germany at least, the restriction to 2500 is required. You’d have to verify if it applies in Netherlands.

Or, “Dont ask, don’t tell”. They pull hard at 2700..... If tach is marked 2500, who will know?

MTV

Thanks MTV! That makes sense. Germany is a lot more busy with practical noise reduction on airplanes than in NL. I guess it doesn't apply here. But now we know why it is. And we can take away the doubts for the pilots flying them. Maybe any source of this info?

Regards
Bert

[mvivion]

Bert,

Get in touch with MT in Germany would likely be best. As you noted the US STC states 2700 max. I don’t have a copy now.

MTV

[skywagon8a]

This is the Type Certificate for the A-1:
https://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/8d3a87c0823d1ff0862581c6006cca2c/$FILE/A22NM_Rev_30.pdf

You will note the references to the MTV-15 propeller indicate the maximum rpm is limited due to noise limitations.

"MTV-15-B/205-58 (includes spinner) (Constant Speed) Diameter not over 80.7 in., not under 79.9 in.Pitch setting at 30 in. stationlow 7.0° ± .2°, high 24.0° ± 1.0°Takeoff & maximum continuous power 2650 RPM(Engine de-rated to 196 HP for noise)"

[mvivion]

Pete,

Okay, okay, 2650 rpm...... picky, picky, picky. All our red lines were set at 2700 from Aviat.....just sayin....

And, the STC for my 170 with the same prop called for 2700.

Interesting. I guess I never looked farther than the tach in the Huskys..

MTV

[skywagon8a]

Nope Mike not being picky only showing Bert where he can find the original noise reason.

[mvivion]

Nope Mike not being picky only showing Bert where he can find the original noise reason.

i know, Pete, just giving you a hard time. But, that info doesn’t apply in EASA countries. They have much more restrictive regs on noise.

MTV