Twin Commander

General Category => Airframe => Twin Commander Turbine => Topic started by: Adam Frisch on March 11, 2019, 02:03:09 pm

Title: 5-blade on the 680's..
Post by: Adam Frisch on March 11, 2019, 02:03:09 pm
Just heard a rumor MT is looking for 680-series turbines to start certifying 5-blades on. Seems like a pretty thin market if you ask me, but if course I'm all for it! Obviously, this would probably cover all the MU-2 series with the smaller props too, so it might not be as small a market as it seems.
Title: Re: 5-blade on the 680's..
Post by: SKYFLYER on March 11, 2019, 03:03:33 pm
Ummm… Maybe offer MT 6 months free use or until certified if they make your bird "whole" again. Might not hurt to even offer to keep the new props on after cert to defray their cost to remove. One can dream now and then 8)
Title: Re: 5-blade on the 680's..
Post by: donv on March 11, 2019, 03:22:04 pm
Do you think there are more than 10 680-series turboprops actively flying, including yours?
Title: Re: 5-blade on the 680's..
Post by: SKYFLYER on March 11, 2019, 04:26:47 pm
There are 12 680 (Y,V,W) currently registered in the US.  How many that are flying... unknown.  There are at least 6 more outside the US that I know of (maybe more) and again unknown how many are flying currently.  Knowing the total number of the variants produced by Commander would shed some light on potential fleet sales. 

But as Adam pointed out, there are several of the MU-2's that would bolster the overall count for certification.
Title: Re: 5-blade on the 680's..
Post by: donv on March 11, 2019, 04:55:03 pm
How does certifying it on a 680 help with an MU-2?
Title: Re: 5-blade on the 680's..
Post by: Bruce Byerly on March 11, 2019, 06:07:28 pm
Is it worth paying $112,000 to slow down? I don’t know - trying to figure out the attraction.
Title: Re: 5-blade on the 680's..
Post by: donv on March 11, 2019, 06:20:06 pm
Bruce, have you had a chance to spend some time flying with the 5-bladed props? What are your impressions?
Title: Re: 5-blade on the 680's..
Post by: Bruce Byerly on March 11, 2019, 10:55:43 pm
Bruce, have you had a chance to spend some time flying with the 5-bladed props? What are your impressions?

No, have you?  I have lots of anecdotal reports from King Air to Mits operators plus the original flight test pilot on the MT install on the 840 way back when. Plus other prop STC experience including the 4 blade Commander and 5 blade King Air. I’m sure the wood props are smooth and quiet but they ought to be. How much do they impact performance? I have no idea. Just seems like breaking new ground with a new, relatively very low time in fleet prop would be a real low priority if one is struggling with basic MX requirements, needs a new panel, etc.  If someone wants to get me a ride, I’ll buy the gas.  I always sold the wide chords with a money back guarantee.  If you didn’t like them, we’d put your old props back on. So far no one has offered me that deal on the MT props. Frankly I got turned off when the 690 came out of the sky with the props in splinters.  But they could be the best thing ever. I don’t know.
Title: Re: 5-blade on the 680's..
Post by: donv on March 11, 2019, 11:31:01 pm
I have not even seen a set in person, let alone flown with one. I have been very happy with the wide chord props that I do have, however.
Title: Re: 5-blade on the 680's..
Post by: Adam Frisch on March 12, 2019, 12:11:26 am
Wasn't the 5-blade 690B that broke up due to overloaded aircraft into a thunderstorm?
Title: Re: 5-blade on the 680's..
Post by: JimC on March 12, 2019, 10:43:54 am
Whoops! I edited Adam's question instead of replying. My bad, mea mea mea Culpa!

I think the NTSB report missed the much more likely cause of tailplane resonance & failure due to an unproven prop, similar to the early Conquest tailplane failures.