03 Dec 2025, 11:55 [ UTC - 5; DST ]
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Post subject: Re: Best jet to replace MU2  Posted: 02 Feb 2015, 00:09 |
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Joined: 02/09/11
Posts: 652
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Company: Aero Teknic Inc.
Location: CYHU / Montreal St-Hubert
Aircraft: MU-2B-60, SR22,C182Q
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Username Protected wrote: Jon, under what conditions are you saying this is true? Standard day, sea level? As a comparison, here's the single engine climb performance data for the MU-2B-60 (Marquise):  Hot/High can be a problem. Note that MU-2s are prohibited from taking off at airports with greater than 8,000 feet pressure altitude elevation (i.e. Telluride, Leadville). -Pascal
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Post subject: Re: Best jet to replace MU2 Posted: 02 Feb 2015, 00:12 |
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Joined: 01/31/10
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Company: 320 Fam
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Username Protected wrote:
Hot/High can be a problem. Note that MU-2s are prohibited from taking off at airports with greater than 8,000 feet pressure altitude elevation (i.e. Telluride, Leadville).
-Pascal
More info please....
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Post subject: Re: Best jet to replace MU2 Posted: 02 Feb 2015, 00:22 |
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Joined: 11/08/12
Posts: 7727
Post Likes: +5112
Location: Live in San Carlos, CA - based Hayward, CA KHWD
Aircraft: Piaggio Avanti
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Username Protected wrote:
Hot/High can be a problem. Note that MU-2s are prohibited from taking off at airports with greater than 8,000 feet pressure altitude elevation (i.e. Telluride, Leadville).
-Pascal
More info please....
This is a tire limitation. The tires are spec'd as 160 mph tires (139 kts). If you do the math on the true airspeed of the indicated speed at rotation, it works out to 139 kts at 8000'.
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-Jon C.
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Post subject: Re: Best jet to replace MU2 Posted: 02 Feb 2015, 00:22 |
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Joined: 02/09/11
Posts: 652
Post Likes: +102
Company: Aero Teknic Inc.
Location: CYHU / Montreal St-Hubert
Aircraft: MU-2B-60, SR22,C182Q
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Username Protected wrote:
Hot/High can be a problem. Note that MU-2s are prohibited from taking off at airports with greater than 8,000 feet pressure altitude elevation (i.e. Telluride, Leadville).
-Pascal
More info please....
It's an AFM limitation:
-Pascal
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Post subject: Re: Best jet to replace MU2 Posted: 02 Feb 2015, 00:26 |
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Joined: 11/08/12
Posts: 7727
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Location: Live in San Carlos, CA - based Hayward, CA KHWD
Aircraft: Piaggio Avanti
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Username Protected wrote: So 9,000'DA is OK, so long as the elevation is less than 8,000'? As expressed in the limitations section, yes.
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-Jon C.
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Post subject: Re: Best jet to replace MU2 Posted: 02 Feb 2015, 00:29 |
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Username Protected wrote: So 9,000'DA is OK, so long as the elevation is less than 8,000'? As expressed in the limitations section, yes.
How about in real life? An airport I frequent pushes 9K DA often.
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Post subject: Re: Best jet to replace MU2 Posted: 02 Feb 2015, 00:35 |
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Joined: 11/08/12
Posts: 7727
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Location: Live in San Carlos, CA - based Hayward, CA KHWD
Aircraft: Piaggio Avanti
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Username Protected wrote: How about in real life? An airport I frequent pushes 9K DA often. I wouldn't be overly concerned about any magic number as long as you're within the limitations section, but as with every airplane in the world, the MU2 is not immune from the performance degradation that comes with being hot/high. So check your performance tables before doing anything in extreme conditions. Another non-obvious temperature related limitation is that you are not supposed to take off at temps greater than ISA+30°C. I believe it's an engine limitation for some reason. I would be shocked if it was not at least occasionally ignored.
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Post subject: Re: Best jet to replace MU2 Posted: 02 Feb 2015, 01:01 |
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Joined: 11/08/12
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Location: Live in San Carlos, CA - based Hayward, CA KHWD
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Username Protected wrote: Is the limitation ISA + 30 or ISA + 37? The King Air is +37. 30 seems a little low? It is ISA+30. It's in the AFM Limitations section (in fact in the snapshot that Pascal posted a couple posts ago). I dunno the technical source of it exactly, my impression is engine related in some way.
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Post subject: Re: Best jet to replace MU2 Posted: 02 Feb 2015, 01:06 |
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Joined: 12/03/14
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Username Protected wrote: This is a tire limitation. The tires are spec'd as 160 mph tires (139 kts). The tire speed is controlled by a separate Vtire limitation which is 139 knots true on the ground. The 8000 ft limitation has nothing to do with the tires. Quote: If you do the math on the true airspeed of the indicated speed at rotation, it works out to 139 kts at 8000'. I compute that 139 KTAS (Vtire assuming zero wind) at 8000 ft in ISA conditions is 123 KIAS indicated, well over any published rotation speed for the MU2. I don't see the connection between Vtire and 8000 ft. The 8000 ft AFM limitation comes from the simple fact the Japanese simply didn't publish performance data for airport operations above 8000 ft. I know of at least one MU2 based at KTEX. While technically in violation of the AFM, there is no fundamental safety issue. Any half wit can extrapolate the performance charts to 10,000 ft. https://www.youtube.com/watch?v=2ujFzjI4RUUhttps://www.youtube.com/watch?v=ED-mHC85p1ohttps://www.youtube.com/watch?v=eXc-BD6GEJAMike C.
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Post subject: Re: Best jet to replace MU2 Posted: 02 Feb 2015, 01:08 |
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Joined: 01/31/10
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Username Protected wrote: This is a tire limitation. The tires are spec'd as 160 mph tires (139 kts). The tire speed is controlled by a separate Vtire limitation which is 139 knots true on the ground. The 8000 ft limitation has nothing to do with the tires. Quote: If you do the math on the true airspeed of the indicated speed at rotation, it works out to 139 kts at 8000'. I compute that 139 KTAS (Vtire assuming zero wind) at 8000 ft in ISA conditions is 123 KIAS indicated, well over any published rotation speed for the MU2. I don't see the connection between Vtire and 8000 ft. The 8000 ft AFM limitation comes from the simple fact the Japanese simply didn't publish performance data for airport operations above 8000 ft. I know of at least one MU2 based at KTEX. While technically in violation of the AFM, there is no fundamental safety issue. Any half wit can extrapolate the performance charts to 10,000 ft. https://www.youtube.com/watch?v=2ujFzjI4RUUhttps://www.youtube.com/watch?v=ED-mHC85p1ohttps://www.youtube.com/watch?v=eXc-BD6GEJAMike C.
That's OK in theory, but if he has a performance related incident he is likely uninsured...no?
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Post subject: Re: Best jet to replace MU2 Posted: 02 Feb 2015, 01:18 |
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Joined: 12/03/14
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Username Protected wrote: Yeah...that is only 108 dF in Phoenix. Both of those limitations would affect me several times a year.. I know an operator based in Phoenix (-6 M model). As Jon said, the limitation is probably violated with no consequence. In Japan, the don't have high elevations or hot temps, so the charts reflect that. The engine TCDS (E4WE) say ambient limits are -40C to +55C, no mention of ISA plus limits. The TCDS may not contain all the limits, however. http://rgl.faa.gov/Regulatory_and_Guida ... Rev_34.pdfMike C.
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Post subject: Re: Best jet to replace MU2 Posted: 02 Feb 2015, 01:20 |
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Joined: 11/08/12
Posts: 7727
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Location: Live in San Carlos, CA - based Hayward, CA KHWD
Aircraft: Piaggio Avanti
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Username Protected wrote: This is a tire limitation. The tires are spec'd as 160 mph tires (139 kts). The tire speed is controlled by a separate Vtire limitation which is 139 knots true on the ground. The 8000 ft limitation has nothing to do with the tires.
Hmm, it was explained to me in training at some point (I don't recall which one anymore) that at the extreme edge of the takeoff performance charts, which include MGTOW, 5° flaps, ISA+30 (i.e. 29°C at 8000'), and up to 10 kts tail wind, the TAS would be over the tire speed limit.
Which, in fact, it is - Vr at 10470 lbs/5° flaps is 110 KIAS, which with all of the above conditions puts TAS at 131 KTAS and with 10 kts tail wind (the max displayed on the takeoff chart in AFM Section 6) puts it just over the 139 KTS limit on the tires...
Perhaps someone figured that must be why and made the conclusion themselves. But that's the portrait that was drawn for me.
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Last edited on 02 Feb 2015, 01:25, edited 2 times in total.
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